Changeset 3c6e417 for src

Timestamp:

Jun 20, 2019, 1:45:01 PM (6 years ago)

Author:

Thierry Delisle <tdelisle@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

54dd994

Parents:

1e5dedc4 (diff), c0f9efe (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Merge branch 'master' of plg.uwaterloo.ca:software/cfa/cfa-cc

Location:

src

Files:

• AST/Convert.cpp (modified) (24 diffs)
• AST/Expr.hpp (modified) (3 diffs)
• AST/Type.hpp (modified) (4 diffs)
• AST/TypeEnvironment.hpp (modified) (1 diff)
• AST/porting.md (modified) (1 diff)
• ResolvExpr/AlternativeFinder.cc (modified) (2 diffs)
• ResolvExpr/Candidate.hpp (modified) (1 diff)
• ResolvExpr/CandidateFinder.cpp (modified) (21 diffs)
• ResolvExpr/CandidateFinder.hpp (modified) (2 diffs)
• ResolvExpr/CastCost.cc (modified) (2 diffs)
• ResolvExpr/ConversionCost.cc (modified) (3 diffs)
• ResolvExpr/PolyCost.cc (modified) (2 diffs)
• ResolvExpr/RenameVars.cc (modified) (1 diff)
• ResolvExpr/RenameVars.h (modified) (1 diff)
• ResolvExpr/ResolveAssertions.cc (modified) (9 diffs)
• ResolvExpr/ResolveTypeof.cc (modified) (1 diff)
• ResolvExpr/ResolveTypeof.h (modified) (1 diff)
• ResolvExpr/Resolver.cc (modified) (1 diff)
• ResolvExpr/Resolver.h (modified) (2 diffs)
• ResolvExpr/SatisfyAssertions.cpp (modified) (1 diff)
• ResolvExpr/SatisfyAssertions.hpp (modified) (1 diff)
• ResolvExpr/SpecCost.cc (modified) (4 diffs)
• ResolvExpr/typeops.h (modified) (3 diffs)
• SymTab/Mangler.h (modified) (1 diff)
• SymTab/Validate.cc (modified) (1 diff)
• SymTab/Validate.h (modified) (2 diffs)
• Tuples/Tuples.cc (modified) (3 diffs)
• Tuples/Tuples.h (modified) (2 diffs)

src/AST/Convert.cpp

@@ -993 +993 @@
         const ast::Expr * visit( const ast::UniqueExpr * node ) override final {
                 auto rslt = new UniqueExpr(
-                        get<Expression>().accept1(node->expr)
+                        get<Expression>().accept1(node->expr),
+                        node->id
                 );
 
@@ -1074 +1075 @@
         }
 
+        const ast::Type * visitType( const ast::Type * node, Type * type ) {
+                // Some types do this in their constructor so add a check.
+                if ( !node->attributes.empty() && type->attributes.empty() ) {
+                        type->attributes = get<Attribute>().acceptL( node->attributes );
+                }
+                this->node = type;
+                return nullptr;
+        }
+
         const ast::Type * visit( const ast::VoidType * node ) override final {
-                this->node = new VoidType{ cv( node ) };
-                return nullptr;
+                return visitType( node, new VoidType{ cv( node ) } );
         }
 
@@ -1085 +1094 @@
                         Validate::SizeType = type;
                 }
-                this->node = type;
-                return nullptr;
+                return visitType( node, type );
         }
 
         const ast::Type * visit( const ast::PointerType * node ) override final {
-                this->node = new PointerType{
+                return visitType( node, new PointerType{
                         cv( node ),
                         get<Type>().accept1( node->base ),
@@ -1096 +1104 @@
                         (bool)node->isVarLen,
                         (bool)node->isStatic
-                };
-                return nullptr;
+                } );
         }
 
         const ast::Type * visit( const ast::ArrayType * node ) override final {
-                this->node = new ArrayType{
+                return visitType( node, new ArrayType{
                         cv( node ),
                         get<Type>().accept1( node->base ),
@@ -1107 +1114 @@
                         (bool)node->isVarLen,
                         (bool)node->isStatic
-                };
-                return nullptr;
+                } );
         }
 
         const ast::Type * visit( const ast::ReferenceType * node ) override final {
-                this->node = new ReferenceType{
+                return visitType( node, new ReferenceType{
                         cv( node ),
                         get<Type>().accept1( node->base )
-                };
-                return nullptr;
+                } );
         }
 
         const ast::Type * visit( const ast::QualifiedType * node ) override final {
-                this->node = new QualifiedType{
+                return visitType( node, new QualifiedType{
                         cv( node ),
                         get<Type>().accept1( node->parent ),
                         get<Type>().accept1( node->child )
-                };
-                return nullptr;
+                } );
         }
 
@@ -1136 +1140 @@
                 ty->parameters = get<DeclarationWithType>().acceptL( node->params );
                 ty->forall = get<TypeDecl>().acceptL( node->forall );
-                this->node = ty;
-                return nullptr;
-        }
-
-        void postvisit( const ast::ReferenceToType * old, ReferenceToType * ty ) {
+                return visitType( node, ty );
+        }
+
+        const ast::Type * postvisit( const ast::ReferenceToType * old, ReferenceToType * ty ) {
                 ty->forall = get<TypeDecl>().acceptL( old->forall );
                 ty->parameters = get<Expression>().acceptL( old->params );
                 ty->hoistType = old->hoistType;
+                return visitType( old, ty );
         }
 
@@ -1161 +1165 @@
                         };
                 }
-                postvisit( node, ty );
-                this->node = ty;
-                return nullptr;
+                return postvisit( node, ty );
         }
 
@@ -1181 +1183 @@
                         };
                 }
-                postvisit( node, ty );
-                this->node = ty;
-                return nullptr;
+                return postvisit( node, ty );
         }
 
@@ -1201 +1201 @@
                         };
                 }
-                postvisit( node, ty );
-                this->node = ty;
-                return nullptr;
+                return postvisit( node, ty );
         }
 
@@ -1221 +1219 @@
                         };
                 }
-                postvisit( node, ty );
-                this->node = ty;
-                return nullptr;
+                return postvisit( node, ty );
         }
 
@@ -1243 +1239 @@
                         };
                 }
-                postvisit( node, ty );
-                this->node = ty;
-                return nullptr;
+                return postvisit( node, ty );
         }
 
         const ast::Type * visit( const ast::TupleType * node ) override final {
-                this->node = new TupleType{
+                return visitType( node, new TupleType{
                         cv( node ),
                         get<Type>().acceptL( node->types )
                         // members generated by TupleType c'tor
-                };
-                return nullptr;
+                } );
         }
 
         const ast::Type * visit( const ast::TypeofType * node ) override final {
-                this->node = new TypeofType{
+                return visitType( node, new TypeofType{
                         cv( node ),
                         get<Expression>().accept1( node->expr ),
                         (bool)node->kind
-                };
-                return nullptr;
+                } );
         }
 
         const ast::Type * visit( const ast::VarArgsType * node ) override final {
-                this->node = new VarArgsType{ cv( node ) };
-                return nullptr;
+                return visitType( node, new VarArgsType{ cv( node ) } );
         }
 
         const ast::Type * visit( const ast::ZeroType * node ) override final {
-                this->node = new ZeroType{ cv( node ) };
-                return nullptr;
+                return visitType( node, new ZeroType{ cv( node ) } );
         }
 
         const ast::Type * visit( const ast::OneType * node ) override final {
-                this->node = new OneType{ cv( node ) };
-                return nullptr;
-        }
-
-        const ast::Type * visit( const ast::GlobalScopeType * ) override final {
-                this->node = new GlobalScopeType{};
-                return nullptr;
+                return visitType( node, new OneType{ cv( node ) } );
+        }
+
+        const ast::Type * visit( const ast::GlobalScopeType * node ) override final {
+                return visitType( node, new GlobalScopeType{} );
         }
 
@@ -2367 +2355 @@
                 auto rslt = new ast::UniqueExpr(
                         old->location,
-                        GET_ACCEPT_1(expr, Expr)
+                        GET_ACCEPT_1(expr, Expr),
+                        old->get_id()
                 );
                 rslt->object = GET_ACCEPT_1(object, ObjectDecl);
@@ -2440 +2429 @@
         }
 
+        void visitType( Type * old, ast::Type * type ) {
+                // Some types do this in their constructor so add a check.
+                if ( !old->attributes.empty() && type->attributes.empty() ) {
+                        type->attributes = GET_ACCEPT_V(attributes, Attribute);
+                }
+                this->node = type;
+        }
+
         virtual void visit( VoidType * old ) override final {
-                this->node = new ast::VoidType{ cv( old ) };
+                visitType( old, new ast::VoidType{ cv( old ) } );
         }
 
@@ -2450 +2447 @@
                         sizeType = type;
                 }
-                this->node = type;
+                visitType( old, type );
         }
 
         virtual void visit( PointerType * old ) override final {
-                this->node = new ast::PointerType{
+                visitType( old, new ast::PointerType{
                         GET_ACCEPT_1( base, Type ),
                         GET_ACCEPT_1( dimension, Expr ),
@@ -2460 +2457 @@
                         (ast::DimensionFlag)old->isStatic,
                         cv( old )
-                };
+                } );
         }
 
         virtual void visit( ArrayType * old ) override final {
-                this->node = new ast::ArrayType{
+                visitType( old, new ast::ArrayType{
                         GET_ACCEPT_1( base, Type ),
                         GET_ACCEPT_1( dimension, Expr ),
@@ -2470 +2467 @@
                         (ast::DimensionFlag)old->isStatic,
                         cv( old )
-                };
+                } );
         }
 
         virtual void visit( ReferenceType * old ) override final {
-                this->node = new ast::ReferenceType{
+                visitType( old, new ast::ReferenceType{
                         GET_ACCEPT_1( base, Type ),
                         cv( old )
-                };
+                } );
         }
 
         virtual void visit( QualifiedType * old ) override final {
-                this->node = new ast::QualifiedType{
+                visitType( old, new ast::QualifiedType{
                         GET_ACCEPT_1( parent, Type ),
                         GET_ACCEPT_1( child, Type ),
                         cv( old )
-                };
+                } );
         }
 
@@ -2496 +2493 @@
                 ty->params = GET_ACCEPT_V( parameters, DeclWithType );
                 ty->forall = GET_ACCEPT_V( forall, TypeDecl );
-                this->node = ty;
+                visitType( old, ty );
         }
 
@@ -2503 +2500 @@
                 ty->params = GET_ACCEPT_V( parameters, Expr );
                 ty->hoistType = old->hoistType;
+                visitType( old, ty );
         }
 
@@ -2521 +2519 @@
                 }
                 postvisit( old, ty );
-                this->node = ty;
         }
 
@@ -2540 +2537 @@
                 }
                 postvisit( old, ty );
-                this->node = ty;
         }
 
@@ -2559 +2555 @@
                 }
                 postvisit( old, ty );
-                this->node = ty;
         }
 
@@ -2578 +2573 @@
                 }
                 postvisit( old, ty );
-                this->node = ty;
         }
 
@@ -2599 +2593 @@
                 }
                 postvisit( old, ty );
-                this->node = ty;
         }
 
         virtual void visit( TupleType * old ) override final {
-                this->node = new ast::TupleType{
+                visitType( old, new ast::TupleType{
                         GET_ACCEPT_V( types, Type ),
                         // members generated by TupleType c'tor
                         cv( old )
-                };
+                } );
         }
 
         virtual void visit( TypeofType * old ) override final {
-                this->node = new ast::TypeofType{
+                visitType( old, new ast::TypeofType{
                         GET_ACCEPT_1( expr, Expr ),
                         (ast::TypeofType::Kind)old->is_basetypeof,
                         cv( old )
-                };
+                } );
         }
 
@@ -2623 +2616 @@
 
         virtual void visit( VarArgsType * old ) override final {
-                this->node = new ast::VarArgsType{ cv( old ) };
+                visitType( old, new ast::VarArgsType{ cv( old ) } );
         }
 
         virtual void visit( ZeroType * old ) override final {
-                this->node = new ast::ZeroType{ cv( old ) };
+                visitType( old, new ast::ZeroType{ cv( old ) } );
         }
 
         virtual void visit( OneType * old ) override final {
-                this->node = new ast::OneType{ cv( old ) };
-        }
-
-        virtual void visit( GlobalScopeType * ) override final {
-                this->node = new ast::GlobalScopeType{};
+                visitType( old, new ast::OneType{ cv( old ) } );
+        }
+
+        virtual void visit( GlobalScopeType * old ) override final {
+                visitType( old, new ast::GlobalScopeType{} );
         }
 

src/AST/Expr.hpp

@@ -47 +47 @@
 
         ParamEntry() : decl( 0 ), declptr( nullptr ), actualType( nullptr ), formalType( nullptr ), expr( nullptr ) {}
-        ParamEntry( UniqueId id, Decl * declptr, Type* actual, Type* formal, Expr* e )
+        ParamEntry( 
+                UniqueId id, const Decl * declptr, const Type * actual, const Type * formal, 
+                const Expr * e )
         : decl( id ), declptr( declptr ), actualType( actual ), formalType( formal ), expr( e ) {}
 };
@@ -129 +131 @@
                         case Params: return data.inferParams;
                         }
+                        assert(!"unreachable");
                         return *((InferredParams*)nullptr);
                 }
@@ -138 +141 @@
                         assert(!"Mode was not already Params");
                         return *((InferredParams*)nullptr);
+                }
+
+                void set_inferParams( InferredParams && ps ) {
+                        switch(mode) {
+                        case Slots: 
+                                data.resnSlots.~ResnSlots();
+                                // fallthrough
+                        case Empty: 
+                                new(&data.inferParams) InferredParams{ std::move( ps ) };
+                                mode = Params;
+                                break;
+                        case Params:
+                                data.inferParams = std::move( ps );
+                                break;
+                        }
                 }
 

src/AST/Type.hpp

@@ -37 +37 @@
 public:
         CV::Qualifiers qualifiers;
-
-        Type( CV::Qualifiers q = {} ) : qualifiers(q) {}
+        std::vector<ptr<Attribute>> attributes;
+
+        Type( CV::Qualifiers q = {}, std::vector<ptr<Attribute>> && as = {} )
+        : qualifiers(q), attributes(std::move(as)) {}
 
         bool is_const() const { return qualifiers.is_const; }
@@ -268 +270 @@
         ForallList forall;
 
-        ParameterizedType( ForallList&& fs = {}, CV::Qualifiers q = {} )
-        : Type(q), forall(std::move(fs)) {}
-        ParameterizedType( CV::Qualifiers q ) : Type(q), forall() {}
+        ParameterizedType( ForallList&& fs = {}, CV::Qualifiers q = {},
+                std::vector<ptr<Attribute>> && as = {} )
+        : Type(q, std::move(as)), forall(std::move(fs)) {}
+
+        ParameterizedType( CV::Qualifiers q, std::vector<ptr<Attribute>> && as = {} )
+        : Type(q, std::move(as)), forall() {}
 
 private:
@@ -311 +316 @@
 public:
         std::vector<ptr<Expr>> params;
-        std::vector<ptr<Attribute>> attributes;
         std::string name;
         bool hoistType = false;
@@ -317 +321 @@
         ReferenceToType( const std::string& n, CV::Qualifiers q = {},
                 std::vector<ptr<Attribute>> && as = {} )
-        : ParameterizedType(q), params(), attributes(std::move(as)), name(n) {}
+        : ParameterizedType(q, std::move(as)), params(), name(n) {}
 
         /// Gets aggregate declaration this type refers to

src/AST/TypeEnvironment.hpp

@@ -215 +215 @@
 std::ostream & operator<<( std::ostream & out, const TypeEnvironment & env );
 
-}
+} // namespace ast
 
 // Local Variables: //

src/AST/porting.md

@@ -302 +302 @@
 * `ExplodedActual.h` => `ExplodedArg.hpp`
 
+`polyCost`
+* switched order of `env`, `symtab` parameters for better consistency
+
+`findMinCost`
+* pulled out conversion cost promotion into separate `promoteCvtCost` function
+
+`resolveAssertions` => `satisfyAssertions`
+* `ResolveAssertions.h` => `SatisfyAssertions.hpp`
+* `Resn*` => `Sat*`
+
 [1] https://gcc.gnu.org/onlinedocs/gcc-9.1.0/gcc/Type-Attributes.html#Type-Attributes
 

src/ResolvExpr/AlternativeFinder.cc

@@ -227 +227 @@
         }
 
-        const ast::Expr * referenceToRvalueConversion( const ast::Expr * expr, Cost & cost ) {
-                if ( expr->result.as< ast::ReferenceType >() ) {
-                        // cast away reference from expr
-                        cost.incReference();
-                        return new ast::CastExpr{ expr->location, expr, expr->result->stripReferences() };
-                }
-                
-                return expr;
-        }
-
         template< typename InputIterator, typename OutputIterator >
         void AlternativeFinder::findSubExprs( InputIterator begin, InputIterator end, OutputIterator out ) {
@@ -518 +508 @@
         }
 
-        /// Unique identifier for matching expression resolutions to their requesting expression
-        UniqueId globalResnSlot = 0;
+        /// Unique identifier for matching expression resolutions to their requesting expression (located in CandidateFinder.cpp)
+        extern UniqueId globalResnSlot;
 
         template< typename OutputIterator >

src/ResolvExpr/Candidate.hpp

@@ -53 +53 @@
         : expr( x ), cost( Cost::zero ), cvtCost( Cost::zero ), env( e ), open(), need() {}
 
-        Candidate( const Candidate & o, const ast::Expr * x )
-        : expr( x ), cost( o.cost ), cvtCost( Cost::zero ), env( o.env ), open( o.open ),
+        Candidate( const Candidate & o, const ast::Expr * x, const Cost & addedCost = Cost::zero )
+        : expr( x ), cost( o.cost + addedCost ), cvtCost( Cost::zero ), env( o.env ), open( o.open ),
           need( o.need ) {}
+
+        Candidate(
+                const ast::Expr * x, const ast::TypeEnvironment & e, const ast::OpenVarSet & o, 
+                const ast::AssertionSet & n, const Cost & c, const Cost & cvt = Cost::zero )
+        : expr( x ), cost( c ), cvtCost( cvt ), env( e ), open( o ), need( n.begin(), n.end() ) {}
 
         Candidate(

src/ResolvExpr/CandidateFinder.cpp

@@ -27 +27 @@
 #include "Cost.h"
 #include "ExplodedArg.hpp"
+#include "RenameVars.h"           // for renameTyVars
 #include "Resolver.h"
+#include "ResolveTypeof.h"
 #include "SatisfyAssertions.hpp"
-#include "typeops.h"              // for adjustExprType
+#include "typeops.h"              // for adjustExprType, conversionCost, polyCost, specCost
 #include "Unify.h"
 #include "AST/Expr.hpp"
@@ -38 +40 @@
 #include "AST/Type.hpp"
 #include "SymTab/Mangler.h"
+#include "SymTab/Validate.h"      // for validateType
 #include "Tuples/Tuples.h"        // for handleTupleAssignment
 
@@ -44 +47 @@
 namespace ResolvExpr {
 
+using std::move;
+
+/// partner to move that copies any copyable type
+template<typename T>
+T copy( const T & x ) { return x; }
+
+const ast::Expr * referenceToRvalueConversion( const ast::Expr * expr, Cost & cost ) {
+        if ( expr->result.as< ast::ReferenceType >() ) {
+                // cast away reference from expr
+                cost.incReference();
+                return new ast::CastExpr{ expr->location, expr, expr->result->stripReferences() };
+        }
+        
+        return expr;
+}
+
+/// Unique identifier for matching expression resolutions to their requesting expression
+UniqueId globalResnSlot = 0;
+
+Cost computeConversionCost( 
+        const ast::Type * argType, const ast::Type * paramType, const ast::SymbolTable & symtab, 
+        const ast::TypeEnvironment & env 
+) {
+        PRINT(
+                std::cerr << std::endl << "converting ";
+                ast::print( std::cerr, argType, 2 );
+                std::cerr << std::endl << " to ";
+                ast::print( std::cerr, paramType, 2 );
+                std::cerr << std::endl << "environment is: ";
+                ast::print( std::cerr, env, 2 );
+                std::cerr << std::endl;
+        )
+        Cost convCost = conversionCost( argType, paramType, symtab, env );
+        PRINT(
+                std::cerr << std::endl << "cost is " << convCost << std::endl;
+        )
+        if ( convCost == Cost::infinity ) return convCost;
+        convCost.incPoly( polyCost( paramType, symtab, env ) + polyCost( argType, symtab, env ) );
+        PRINT(
+                std::cerr << "cost with polycost is " << convCost << std::endl;
+        )
+        return convCost;
+}
+
 namespace {
-
         /// First index is which argument, second is which alternative, third is which exploded element
         using ExplodedArgs_new = std::deque< std::vector< ExplodedArg > >;
@@ -65 +111 @@
         }
 
+        /// Computes conversion cost for a given expression to a given type
+        const ast::Expr * computeExpressionConversionCost( 
+                const ast::Expr * arg, const ast::Type * paramType, const ast::SymbolTable & symtab, const ast::TypeEnvironment & env, Cost & outCost 
+        ) {
+                Cost convCost = computeConversionCost( arg->result, paramType, symtab, env );
+                outCost += convCost;
+
+                // If there is a non-zero conversion cost, ignoring poly cost, then the expression requires 
+                // conversion. Ignore poly cost for now, since this requires resolution of the cast to 
+                // infer parameters and this does not currently work for the reason stated below
+                Cost tmpCost = convCost;
+                tmpCost.incPoly( -tmpCost.get_polyCost() );
+                if ( tmpCost != Cost::zero ) {
+                        ast::ptr< ast::Type > newType = paramType;
+                        env.apply( newType );
+                        return new ast::CastExpr{ arg->location, arg, newType };
+
+                        // xxx - *should* be able to resolve this cast, but at the moment pointers are not 
+                        // castable to zero_t, but are implicitly convertible. This is clearly inconsistent, 
+                        // once this is fixed it should be possible to resolve the cast.
+                        // xxx - this isn't working, it appears because type1 (parameter) is seen as widenable, 
+                        // but it shouldn't be because this makes the conversion from DT* to DT* since 
+                        // commontype(zero_t, DT*) is DT*, rather than nothing
+
+                        // CandidateFinder finder{ symtab, env };
+                        // finder.find( arg, ResolvMode::withAdjustment() );
+                        // assertf( finder.candidates.size() > 0, 
+                        //      "Somehow castable expression failed to find alternatives." );
+                        // assertf( finder.candidates.size() == 1, 
+                        //      "Somehow got multiple alternatives for known cast expression." );
+                        // return finder.candidates.front()->expr;
+                }
+
+                return arg;
+        }
+
         /// Computes conversion cost for a given candidate
         Cost computeApplicationConversionCost( 
-                const CandidateRef & cand, const ast::SymbolTable & symtab 
+                CandidateRef cand, const ast::SymbolTable & symtab 
         ) {
-                #warning unimplemented
-                (void)cand; (void)symtab;
-                assert(false);
-                return Cost::infinity;
+                auto appExpr = cand->expr.strict_as< ast::ApplicationExpr >();
+                auto pointer = appExpr->func->result.strict_as< ast::PointerType >();
+                auto function = pointer->base.strict_as< ast::FunctionType >();
+
+                Cost convCost = Cost::zero;
+                const auto & params = function->params;
+                auto param = params.begin();
+                auto & args = appExpr->args;
+
+                for ( unsigned i = 0; i < args.size(); ++i ) {
+                        const ast::Type * argType = args[i]->result;
+                        PRINT(
+                                std::cerr << "arg expression:" << std::endl;
+                                ast::print( std::cerr, args[i], 2 );
+                                std::cerr << "--- results are" << std::endl;
+                                ast::print( std::cerr, argType, 2 );
+                        )
+
+                        if ( param == params.end() ) {
+                                if ( function->isVarArgs ) {
+                                        convCost.incUnsafe();
+                                        PRINT( std::cerr << "end of params with varargs function: inc unsafe: " 
+                                                << convCost << std::endl; ; )
+                                        // convert reference-typed expressions into value-typed expressions
+                                        cand->expr = ast::mutate_field_index( 
+                                                appExpr, &ast::ApplicationExpr::args, i, 
+                                                referenceToRvalueConversion( args[i], convCost ) );
+                                        continue;
+                                } else return Cost::infinity;
+                        }
+
+                        if ( auto def = args[i].as< ast::DefaultArgExpr >() ) {
+                                // Default arguments should be free - don't include conversion cost.
+                                // Unwrap them here because they are not relevant to the rest of the system
+                                cand->expr = ast::mutate_field_index( 
+                                        appExpr, &ast::ApplicationExpr::args, i, def->expr );
+                                ++param;
+                                continue;
+                        }
+
+                        // mark conversion cost and also specialization cost of param type
+                        const ast::Type * paramType = (*param)->get_type();
+                        cand->expr = ast::mutate_field_index( 
+                                appExpr, &ast::ApplicationExpr::args, i, 
+                                computeExpressionConversionCost( 
+                                        args[i], paramType, symtab, cand->env, convCost ) );
+                        convCost.decSpec( specCost( paramType ) );
+                        ++param;  // can't be in for-loop update because of the continue
+                }
+
+                if ( param != params.end() ) return Cost::infinity;
+
+                // specialization cost of return types can't be accounted for directly, it disables 
+                // otherwise-identical calls, like this example based on auto-newline in the I/O lib:
+                //
+                //   forall(otype OS) {
+                //     void ?|?(OS&, int);  // with newline
+                //     OS&  ?|?(OS&, int);  // no newline, always chosen due to more specialization
+                //   }
+
+                // mark type variable and specialization cost of forall clause
+                convCost.incVar( function->forall.size() );
+                for ( const ast::TypeDecl * td : function->forall ) {
+                        convCost.decSpec( td->assertions.size() );
+                }
+
+                return convCost;
+        }
+
+        void makeUnifiableVars( 
+                const ast::ParameterizedType * type, ast::OpenVarSet & unifiableVars, 
+                ast::AssertionSet & need 
+        ) {
+                for ( const ast::TypeDecl * tyvar : type->forall ) {
+                        unifiableVars[ tyvar->name ] = ast::TypeDecl::Data{ tyvar };
+                        for ( const ast::DeclWithType * assn : tyvar->assertions ) {
+                                need[ assn ].isUsed = true;
+                        }
+                }
+        }
+
+        /// Gets a default value from an initializer, nullptr if not present
+        const ast::ConstantExpr * getDefaultValue( const ast::Init * init ) {
+                if ( auto si = dynamic_cast< const ast::SingleInit * >( init ) ) {
+                        if ( auto ce = si->value.as< ast::CastExpr >() ) {
+                                return ce->arg.as< ast::ConstantExpr >();
+                        } else {
+                                return si->value.as< ast::ConstantExpr >();
+                        }
+                }
+                return nullptr;
+        }
+
+        /// State to iteratively build a match of parameter expressions to arguments
+        struct ArgPack {
+                std::size_t parent;          ///< Index of parent pack
+                ast::ptr< ast::Expr > expr;  ///< The argument stored here
+                Cost cost;                   ///< The cost of this argument
+                ast::TypeEnvironment env;    ///< Environment for this pack
+                ast::AssertionSet need;      ///< Assertions outstanding for this pack
+                ast::AssertionSet have;      ///< Assertions found for this pack
+                ast::OpenVarSet open;        ///< Open variables for this pack
+                unsigned nextArg;            ///< Index of next argument in arguments list
+                unsigned tupleStart;         ///< Number of tuples that start at this index
+                unsigned nextExpl;           ///< Index of next exploded element
+                unsigned explAlt;            ///< Index of alternative for nextExpl > 0
+
+                ArgPack()
+                : parent( 0 ), expr(), cost( Cost::zero ), env(), need(), have(), open(), nextArg( 0 ), 
+                  tupleStart( 0 ), nextExpl( 0 ), explAlt( 0 ) {}
+                
+                ArgPack( 
+                        const ast::TypeEnvironment & env, const ast::AssertionSet & need, 
+                        const ast::AssertionSet & have, const ast::OpenVarSet & open )
+                : parent( 0 ), expr(), cost( Cost::zero ), env( env ), need( need ), have( have ), 
+                  open( open ), nextArg( 0 ), tupleStart( 0 ), nextExpl( 0 ), explAlt( 0 ) {}
+                
+                ArgPack(
+                        std::size_t parent, const ast::Expr * expr, ast::TypeEnvironment && env, 
+                        ast::AssertionSet && need, ast::AssertionSet && have, ast::OpenVarSet && open, 
+                        unsigned nextArg, unsigned tupleStart = 0, Cost cost = Cost::zero, 
+                        unsigned nextExpl = 0, unsigned explAlt = 0 )
+                : parent(parent), expr( expr ), cost( cost ), env( move( env ) ), need( move( need ) ),
+                  have( move( have ) ), open( move( open ) ), nextArg( nextArg ), tupleStart( tupleStart ),
+                  nextExpl( nextExpl ), explAlt( explAlt ) {}
+                
+                ArgPack(
+                        const ArgPack & o, ast::TypeEnvironment && env, ast::AssertionSet && need, 
+                        ast::AssertionSet && have, ast::OpenVarSet && open, unsigned nextArg, Cost added )
+                : parent( o.parent ), expr( o.expr ), cost( o.cost + added ), env( move( env ) ), 
+                  need( move( need ) ), have( move( have ) ), open( move( open ) ), nextArg( nextArg ), 
+                  tupleStart( o.tupleStart ), nextExpl( 0 ), explAlt( 0 ) {}
+                
+                /// true if this pack is in the middle of an exploded argument
+                bool hasExpl() const { return nextExpl > 0; }
+
+                /// Gets the list of exploded candidates for this pack
+                const ExplodedArg & getExpl( const ExplodedArgs_new & args ) const {
+                        return args[ nextArg-1 ][ explAlt ];
+                }
+                
+                /// Ends a tuple expression, consolidating the appropriate args
+                void endTuple( const std::vector< ArgPack > & packs ) {
+                        // add all expressions in tuple to list, summing cost
+                        std::deque< const ast::Expr * > exprs;
+                        const ArgPack * pack = this;
+                        if ( expr ) { exprs.emplace_front( expr ); }
+                        while ( pack->tupleStart == 0 ) {
+                                pack = &packs[pack->parent];
+                                exprs.emplace_front( pack->expr );
+                                cost += pack->cost;
+                        }
+                        // reset pack to appropriate tuple
+                        std::vector< ast::ptr< ast::Expr > > exprv( exprs.begin(), exprs.end() );
+                        expr = new ast::TupleExpr{ expr->location, move( exprv ) };
+                        tupleStart = pack->tupleStart - 1;
+                        parent = pack->parent;
+                }
+        };
+
+        /// Instantiates an argument to match a parameter, returns false if no matching results left
+        bool instantiateArgument( 
+                const ast::Type * paramType, const ast::Init * init, const ExplodedArgs_new & args, 
+                std::vector< ArgPack > & results, std::size_t & genStart, const ast::SymbolTable & symtab, 
+                unsigned nTuples = 0 
+        ) {
+                if ( auto tupleType = dynamic_cast< const ast::TupleType * >( paramType ) ) {
+                        // paramType is a TupleType -- group args into a TupleExpr
+                        ++nTuples;
+                        for ( const ast::Type * type : *tupleType ) {
+                                // xxx - dropping initializer changes behaviour from previous, but seems correct
+                                // ^^^ need to handle the case where a tuple has a default argument
+                                if ( ! instantiateArgument( 
+                                        type, nullptr, args, results, genStart, symtab, nTuples ) ) return false;
+                                nTuples = 0;
+                        }
+                        // re-constitute tuples for final generation
+                        for ( auto i = genStart; i < results.size(); ++i ) {
+                                results[i].endTuple( results );
+                        }
+                        return true;
+                } else if ( const ast::TypeInstType * ttype = Tuples::isTtype( paramType ) ) {
+                        // paramType is a ttype, consumes all remaining arguments
+                        
+                        // completed tuples; will be spliced to end of results to finish
+                        std::vector< ArgPack > finalResults{};
+
+                        // iterate until all results completed
+                        std::size_t genEnd;
+                        ++nTuples;
+                        do {
+                                genEnd = results.size();
+
+                                // add another argument to results
+                                for ( std::size_t i = genStart; i < genEnd; ++i ) {
+                                        unsigned nextArg = results[i].nextArg;
+                                        
+                                        // use next element of exploded tuple if present
+                                        if ( results[i].hasExpl() ) {
+                                                const ExplodedArg & expl = results[i].getExpl( args );
+
+                                                unsigned nextExpl = results[i].nextExpl + 1;
+                                                if ( nextExpl == expl.exprs.size() ) { nextExpl = 0; }
+
+                                                results.emplace_back(
+                                                        i, expl.exprs[ results[i].nextExpl ], copy( results[i].env ),
+                                                        copy( results[i].need ), copy( results[i].have ), 
+                                                        copy( results[i].open ), nextArg, nTuples, Cost::zero, nextExpl,
+                                                        results[i].explAlt );
+
+                                                continue;
+                                        }
+
+                                        // finish result when out of arguments
+                                        if ( nextArg >= args.size() ) {
+                                                ArgPack newResult{
+                                                        results[i].env, results[i].need, results[i].have, results[i].open };
+                                                newResult.nextArg = nextArg;
+                                                const ast::Type * argType = nullptr;
+
+                                                if ( nTuples > 0 || ! results[i].expr ) {
+                                                        // first iteration or no expression to clone,
+                                                        // push empty tuple expression
+                                                        newResult.parent = i;
+                                                        std::vector< ast::ptr< ast::Expr > > emptyList;
+                                                        newResult.expr = 
+                                                                new ast::TupleExpr{ CodeLocation{}, move( emptyList ) };
+                                                        argType = newResult.expr->result;
+                                                } else {
+                                                        // clone result to collect tuple
+                                                        newResult.parent = results[i].parent;
+                                                        newResult.cost = results[i].cost;
+                                                        newResult.tupleStart = results[i].tupleStart;
+                                                        newResult.expr = results[i].expr;
+                                                        argType = newResult.expr->result;
+
+                                                        if ( results[i].tupleStart > 0 && Tuples::isTtype( argType ) ) {
+                                                                // the case where a ttype value is passed directly is special,
+                                                                // e.g. for argument forwarding purposes
+                                                                // xxx - what if passing multiple arguments, last of which is
+                                                                //       ttype?
+                                                                // xxx - what would happen if unify was changed so that unifying
+                                                                //       tuple
+                                                                // types flattened both before unifying lists? then pass in
+                                                                // TupleType (ttype) below.
+                                                                --newResult.tupleStart;
+                                                        } else {
+                                                                // collapse leftover arguments into tuple
+                                                                newResult.endTuple( results );
+                                                                argType = newResult.expr->result;
+                                                        }
+                                                }
+
+                                                // check unification for ttype before adding to final
+                                                if ( 
+                                                        unify( 
+                                                                ttype, argType, newResult.env, newResult.need, newResult.have,
+                                                                newResult.open, symtab ) 
+                                                ) {
+                                                        finalResults.emplace_back( move( newResult ) );
+                                                }
+
+                                                continue;
+                                        }
+
+                                        // add each possible next argument
+                                        for ( std::size_t j = 0; j < args[nextArg].size(); ++j ) {
+                                                const ExplodedArg & expl = args[nextArg][j];
+
+                                                // fresh copies of parent parameters for this iteration
+                                                ast::TypeEnvironment env = results[i].env;
+                                                ast::OpenVarSet open = results[i].open;
+
+                                                env.addActual( expl.env, open );
+
+                                                // skip empty tuple arguments by (nearly) cloning parent into next gen
+                                                if ( expl.exprs.empty() ) {
+                                                        results.emplace_back(
+                                                                results[i], move( env ), copy( results[i].need ), 
+                                                                copy( results[i].have ), move( open ), nextArg + 1, expl.cost );
+                                                        
+                                                        continue;
+                                                }
+
+                                                // add new result
+                                                results.emplace_back(
+                                                        i, expl.exprs.front(), move( env ), copy( results[i].need ), 
+                                                        copy( results[i].have ), move( open ), nextArg + 1, nTuples, 
+                                                        expl.cost, expl.exprs.size() == 1 ? 0 : 1, j );
+                                        }
+                                }
+
+                                // reset for next round
+                                genStart = genEnd;
+                                nTuples = 0;
+                        } while ( genEnd != results.size() );
+
+                        // splice final results onto results
+                        for ( std::size_t i = 0; i < finalResults.size(); ++i ) {
+                                results.emplace_back( move( finalResults[i] ) );
+                        }
+                        return ! finalResults.empty();
+                }
+
+                // iterate each current subresult
+                std::size_t genEnd = results.size();
+                for ( std::size_t i = genStart; i < genEnd; ++i ) {
+                        unsigned nextArg = results[i].nextArg;
+
+                        // use remainder of exploded tuple if present
+                        if ( results[i].hasExpl() ) {
+                                const ExplodedArg & expl = results[i].getExpl( args );
+                                const ast::Expr * expr = expl.exprs[ results[i].nextExpl ];
+
+                                ast::TypeEnvironment env = results[i].env;
+                                ast::AssertionSet need = results[i].need, have = results[i].have;
+                                ast::OpenVarSet open = results[i].open;
+
+                                const ast::Type * argType = expr->result;
+
+                                PRINT(
+                                        std::cerr << "param type is ";
+                                        ast::print( std::cerr, paramType );
+                                        std::cerr << std::endl << "arg type is ";
+                                        ast::print( std::cerr, argType );
+                                        std::cerr << std::endl;
+                                )
+
+                                if ( unify( paramType, argType, env, need, have, open, symtab ) ) {
+                                        unsigned nextExpl = results[i].nextExpl + 1;
+                                        if ( nextExpl == expl.exprs.size() ) { nextExpl = 0; }
+
+                                        results.emplace_back(
+                                                i, expr, move( env ), move( need ), move( have ), move( open ), nextArg, 
+                                                nTuples, Cost::zero, nextExpl, results[i].explAlt );
+                                }
+
+                                continue;
+                        }
+
+                        // use default initializers if out of arguments
+                        if ( nextArg >= args.size() ) {
+                                if ( const ast::ConstantExpr * cnst = getDefaultValue( init ) ) {
+                                        ast::TypeEnvironment env = results[i].env;
+                                        ast::AssertionSet need = results[i].need, have = results[i].have;
+                                        ast::OpenVarSet open = results[i].open;
+
+                                        if ( unify( paramType, cnst->result, env, need, have, open, symtab ) ) {
+                                                results.emplace_back(
+                                                        i, new ast::DefaultArgExpr{ cnst->location, cnst }, move( env ), 
+                                                        move( need ), move( have ), move( open ), nextArg, nTuples );
+                                        }
+                                }
+
+                                continue;
+                        }
+
+                        // Check each possible next argument
+                        for ( std::size_t j = 0; j < args[nextArg].size(); ++j ) {
+                                const ExplodedArg & expl = args[nextArg][j];
+
+                                // fresh copies of parent parameters for this iteration
+                                ast::TypeEnvironment env = results[i].env;
+                                ast::AssertionSet need = results[i].need, have = results[i].have;
+                                ast::OpenVarSet open = results[i].open;
+
+                                env.addActual( expl.env, open );
+
+                                // skip empty tuple arguments by (nearly) cloning parent into next gen
+                                if ( expl.exprs.empty() ) {
+                                        results.emplace_back(
+                                                results[i], move( env ), move( need ), move( have ), move( open ), 
+                                                nextArg + 1, expl.cost );
+                                        
+                                        continue;
+                                }
+
+                                // consider only first exploded arg
+                                const ast::Expr * expr = expl.exprs.front();
+                                const ast::Type * argType = expr->result;
+
+                                PRINT(
+                                        std::cerr << "param type is ";
+                                        ast::print( std::cerr, paramType );
+                                        std::cerr << std::endl << "arg type is ";
+                                        ast::print( std::cerr, argType );
+                                        std::cerr << std::endl;
+                                )
+
+                                // attempt to unify types
+                                if ( unify( paramType, argType, env, need, have, open, symtab ) ) {
+                                        // add new result
+                                        results.emplace_back(
+                                                i, expr, move( env ), move( need ), move( have ), move( open ), 
+                                                nextArg + 1, nTuples, expl.cost, expl.exprs.size() == 1 ? 0 : 1, j );
+                                }
+                        }
+                }
+
+                // reset for next parameter
+                genStart = genEnd;
+
+                return genEnd != results.size();
+        }
+
+        /// Generate a cast expression from `arg` to `toType`
+        const ast::Expr * restructureCast( 
+                ast::ptr< ast::Expr > & arg, const ast::Type * toType, ast::GeneratedFlag isGenerated = ast::GeneratedCast
+        ) {
+                if ( 
+                        arg->result->size() > 1 
+                        && ! toType->isVoid() 
+                        && ! dynamic_cast< const ast::ReferenceType * >( toType ) 
+                ) {
+                        // Argument is a tuple and the target type is neither void nor a reference. Cast each 
+                        // member of the tuple to its corresponding target type, producing the tuple of those 
+                        // cast expressions. If there are more components of the tuple than components in the 
+                        // target type, then excess components do not come out in the result expression (but 
+                        // UniqueExpr ensures that the side effects will still be produced)
+                        if ( Tuples::maybeImpureIgnoreUnique( arg ) ) {
+                                // expressions which may contain side effects require a single unique instance of 
+                                // the expression
+                                arg = new ast::UniqueExpr{ arg->location, arg };
+                        }
+                        std::vector< ast::ptr< ast::Expr > > components;
+                        for ( unsigned i = 0; i < toType->size(); ++i ) {
+                                // cast each component
+                                ast::ptr< ast::Expr > idx = new ast::TupleIndexExpr{ arg->location, arg, i };
+                                components.emplace_back( 
+                                        restructureCast( idx, toType->getComponent( i ), isGenerated ) );
+                        }
+                        return new ast::TupleExpr{ arg->location, move( components ) };
+                } else {
+                        // handle normally
+                        return new ast::CastExpr{ arg->location, arg, toType, isGenerated };
+                }
+        }
+
+        /// Gets the name from an untyped member expression (must be NameExpr)
+        const std::string & getMemberName( const ast::UntypedMemberExpr * memberExpr ) {
+                if ( memberExpr->member.as< ast::ConstantExpr >() ) {
+                        SemanticError( memberExpr, "Indexed access to struct fields unsupported: " );
+                }
+
+                return memberExpr->member.strict_as< ast::NameExpr >()->name;
         }
 
@@ -99 +622 @@
                 }
 
+                /// Set up candidate assertions for inference
+                void inferParameters( CandidateRef & newCand, CandidateList & out ) {
+                        // Set need bindings for any unbound assertions
+                        UniqueId crntResnSlot = 0; // matching ID for this expression's assertions
+                        for ( auto & assn : newCand->need ) {
+                                // skip already-matched assertions
+                                if ( assn.second.resnSlot != 0 ) continue;
+                                // assign slot for expression if needed
+                                if ( crntResnSlot == 0 ) { crntResnSlot = ++globalResnSlot; }
+                                // fix slot to assertion
+                                assn.second.resnSlot = crntResnSlot;
+                        }
+                        // pair slot to expression
+                        if ( crntResnSlot != 0 ) {
+                                newCand->expr.get_and_mutate()->inferred.resnSlots().emplace_back( crntResnSlot );
+                        }
+
+                        // add to output list; assertion satisfaction will occur later
+                        out.emplace_back( newCand );
+                }
+
+                /// Completes a function candidate with arguments located
+                void validateFunctionCandidate( 
+                        const CandidateRef & func, ArgPack & result, const std::vector< ArgPack > & results, 
+                        CandidateList & out 
+                ) {
+                        ast::ApplicationExpr * appExpr = 
+                                new ast::ApplicationExpr{ func->expr->location, func->expr };
+                        // sum cost and accumulate arguments
+                        std::deque< const ast::Expr * > args;
+                        Cost cost = func->cost;
+                        const ArgPack * pack = &result;
+                        while ( pack->expr ) {
+                                args.emplace_front( pack->expr );
+                                cost += pack->cost;
+                                pack = &results[pack->parent];
+                        }
+                        std::vector< ast::ptr< ast::Expr > > vargs( args.begin(), args.end() );
+                        appExpr->args = move( vargs );
+                        // build and validate new candidate
+                        auto newCand = 
+                                std::make_shared<Candidate>( appExpr, result.env, result.open, result.need, cost );
+                        PRINT(
+                                std::cerr << "instantiate function success: " << appExpr << std::endl;
+                                std::cerr << "need assertions:" << std::endl;
+                                ast::print( std::cerr, result.need, 2 );
+                        )
+                        inferParameters( newCand, out );
+                }
+
                 /// Builds a list of candidates for a function, storing them in out
                 void makeFunctionCandidates(
@@ -104 +677 @@
                         const ExplodedArgs_new & args, CandidateList & out
                 ) {
-                        #warning unimplemented
-                        (void)func; (void)funcType; (void)args; (void)out;
-                        assert(false);
+                        ast::OpenVarSet funcOpen;
+                        ast::AssertionSet funcNeed, funcHave;
+                        ast::TypeEnvironment funcEnv{ func->env };
+                        makeUnifiableVars( funcType, funcOpen, funcNeed );
+                        // add all type variables as open variables now so that those not used in the parameter 
+                        // list are still considered open
+                        funcEnv.add( funcType->forall );
+
+                        if ( targetType && ! targetType->isVoid() && ! funcType->returns.empty() ) {
+                                // attempt to narrow based on expected target type
+                                const ast::Type * returnType = funcType->returns.front()->get_type();
+                                if ( ! unify( 
+                                        returnType, targetType, funcEnv, funcNeed, funcHave, funcOpen, symtab ) 
+                                ) {
+                                        // unification failed, do not pursue this candidate
+                                        return;
+                                }
+                        }
+
+                        // iteratively build matches, one parameter at a time
+                        std::vector< ArgPack > results;
+                        results.emplace_back( funcEnv, funcNeed, funcHave, funcOpen );
+                        std::size_t genStart = 0;
+
+                        for ( const ast::DeclWithType * param : funcType->params ) {
+                                auto obj = strict_dynamic_cast< const ast::ObjectDecl * >( param );
+                                // Try adding the arguments corresponding to the current parameter to the existing 
+                                // matches
+                                if ( ! instantiateArgument( 
+                                        obj->type, obj->init, args, results, genStart, symtab ) ) return;
+                        }
+
+                        if ( funcType->isVarArgs ) {
+                                // append any unused arguments to vararg pack
+                                std::size_t genEnd;
+                                do {
+                                        genEnd = results.size();
+
+                                        // iterate results
+                                        for ( std::size_t i = genStart; i < genEnd; ++i ) {
+                                                unsigned nextArg = results[i].nextArg;
+
+                                                // use remainder of exploded tuple if present
+                                                if ( results[i].hasExpl() ) {
+                                                        const ExplodedArg & expl = results[i].getExpl( args );
+
+                                                        unsigned nextExpl = results[i].nextExpl + 1;
+                                                        if ( nextExpl == expl.exprs.size() ) { nextExpl = 0; }
+
+                                                        results.emplace_back(
+                                                                i, expl.exprs[ results[i].nextExpl ], copy( results[i].env ),
+                                                                copy( results[i].need ), copy( results[i].have ),
+                                                                copy( results[i].open ), nextArg, 0, Cost::zero, nextExpl,
+                                                                results[i].explAlt );
+
+                                                        continue;
+                                                }
+
+                                                // finish result when out of arguments
+                                                if ( nextArg >= args.size() ) {
+                                                        validateFunctionCandidate( func, results[i], results, out );
+
+                                                        continue;
+                                                }
+
+                                                // add each possible next argument
+                                                for ( std::size_t j = 0; j < args[nextArg].size(); ++j ) {
+                                                        const ExplodedArg & expl = args[nextArg][j];
+
+                                                        // fresh copies of parent parameters for this iteration
+                                                        ast::TypeEnvironment env = results[i].env;
+                                                        ast::OpenVarSet open = results[i].open;
+
+                                                        env.addActual( expl.env, open );
+
+                                                        // skip empty tuple arguments by (nearly) cloning parent into next gen
+                                                        if ( expl.exprs.empty() ) {
+                                                                results.emplace_back(
+                                                                        results[i], move( env ), copy( results[i].need ), 
+                                                                        copy( results[i].have ), move( open ), nextArg + 1, 
+                                                                        expl.cost );
+
+                                                                continue;
+                                                        }
+
+                                                        // add new result
+                                                        results.emplace_back(
+                                                                i, expl.exprs.front(), move( env ), copy( results[i].need ),
+                                                                copy( results[i].have ), move( open ), nextArg + 1, 0, expl.cost, 
+                                                                expl.exprs.size() == 1 ? 0 : 1, j );
+                                                }
+                                        }
+
+                                        genStart = genEnd;
+                                } while( genEnd != results.size() );
+                        } else {
+                                // filter out the results that don't use all the arguments
+                                for ( std::size_t i = genStart; i < results.size(); ++i ) {
+                                        ArgPack & result = results[i];
+                                        if ( ! result.hasExpl() && result.nextArg >= args.size() ) {
+                                                validateFunctionCandidate( func, result, results, out );
+                                        }
+                                }
+                        }
                 }
 
                 /// Adds implicit struct-conversions to the alternative list
                 void addAnonConversions( const CandidateRef & cand ) {
-                        #warning unimplemented
-                        (void)cand;
-                        assert(false);
+                        // adds anonymous member interpretations whenever an aggregate value type is seen. 
+                        // it's okay for the aggregate expression to have reference type -- cast it to the 
+                        // base type to treat the aggregate as the referenced value
+                        ast::ptr< ast::Expr > aggrExpr( cand->expr );
+                        ast::ptr< ast::Type > & aggrType = aggrExpr.get_and_mutate()->result;
+                        cand->env.apply( aggrType );
+                        
+                        if ( aggrType.as< ast::ReferenceType >() ) {
+                                aggrExpr = 
+                                        new ast::CastExpr{ aggrExpr->location, aggrExpr, aggrType->stripReferences() };
+                        }
+
+                        if ( auto structInst = aggrExpr->result.as< ast::StructInstType >() ) {
+                                addAggMembers( structInst, aggrExpr, *cand, Cost::safe, "" );
+                        } else if ( auto unionInst = aggrExpr->result.as< ast::UnionInstType >() ) {
+                                addAggMembers( unionInst, aggrExpr, *cand, Cost::safe, "" );
+                        }
+                }
+
+                /// Adds aggregate member interpretations
+                void addAggMembers( 
+                        const ast::ReferenceToType * aggrInst, const ast::Expr * expr, 
+                        const Candidate & cand, const Cost & addedCost, const std::string & name 
+                ) {
+                        for ( const ast::Decl * decl : aggrInst->lookup( name ) ) {
+                                auto dwt = strict_dynamic_cast< const ast::DeclWithType * >( decl );
+                                CandidateRef newCand = std::make_shared<Candidate>( 
+                                        cand, new ast::MemberExpr{ expr->location, dwt, expr }, addedCost );
+                                // add anonymous member interpretations whenever an aggregate value type is seen 
+                                // as a member expression
+                                addAnonConversions( newCand );
+                                candidates.emplace_back( move( newCand ) );
+                        }
+                }
+
+                /// Adds tuple member interpretations
+                void addTupleMembers( 
+                        const ast::TupleType * tupleType, const ast::Expr * expr, const Candidate & cand, 
+                        const Cost & addedCost, const ast::Expr * member 
+                ) {
+                        if ( auto constantExpr = dynamic_cast< const ast::ConstantExpr * >( member ) ) {
+                                // get the value of the constant expression as an int, must be between 0 and the 
+                                // length of the tuple to have meaning
+                                long long val = constantExpr->intValue();
+                                if ( val >= 0 && (unsigned long long)val < tupleType->size() ) {
+                                        addCandidate(
+                                                cand, new ast::TupleIndexExpr{ expr->location, expr, (unsigned)val }, 
+                                                addedCost );
+                                }
+                        }
                 }
 
@@ -189 +910 @@
                                         funcE.emplace_back( *func, symtab );
                                 }
-                                argExpansions.emplace_front( std::move( funcE ) );
+                                argExpansions.emplace_front( move( funcE ) );
 
                                 for ( const CandidateRef & op : opFinder ) {
@@ -233 +954 @@
                                 if ( cvtCost != Cost::infinity ) {
                                         withFunc->cvtCost = cvtCost;
-                                        candidates.emplace_back( std::move( withFunc ) );
-                                }
-                        }
-                        found = std::move( candidates );
+                                        candidates.emplace_back( move( withFunc ) );
+                                }
+                        }
+                        found = move( candidates );
 
                         // use a new list so that candidates are not examined by addAnonConversions twice
@@ -285 +1006 @@
 
                 void postvisit( const ast::CastExpr * castExpr ) {
-                        #warning unimplemented
-                        (void)castExpr;
-                        assert(false);
+                        ast::ptr< ast::Type > toType = castExpr->result;
+                        assert( toType );
+                        toType = resolveTypeof( toType, symtab );
+                        toType = SymTab::validateType( toType, symtab );
+                        toType = adjustExprType( toType, tenv, symtab );
+
+                        CandidateFinder finder{ symtab, tenv, toType };
+                        finder.find( castExpr->arg, ResolvMode::withAdjustment() );
+
+                        CandidateList matches;
+                        for ( CandidateRef & cand : finder.candidates ) {
+                                ast::AssertionSet need( cand->need.begin(), cand->need.end() ), have;
+                                ast::OpenVarSet open( cand->open );
+
+                                cand->env.extractOpenVars( open );
+
+                                // It is possible that a cast can throw away some values in a multiply-valued 
+                                // expression, e.g. cast-to-void, one value to zero. Figure out the prefix of the 
+                                // subexpression results that are cast directly. The candidate is invalid if it 
+                                // has fewer results than there are types to cast to.
+                                int discardedValues = cand->expr->result->size() - toType->size();
+                                if ( discardedValues < 0 ) continue;
+
+                                // unification run for side-effects
+                                unify( toType, cand->expr->result, cand->env, need, have, open, symtab );
+                                Cost thisCost = castCost( cand->expr->result, toType, symtab, cand->env );
+                                PRINT(
+                                        std::cerr << "working on cast with result: " << toType << std::endl;
+                                        std::cerr << "and expr type: " << cand->expr->result << std::endl;
+                                        std::cerr << "env: " << cand->env << std::endl;
+                                )
+                                if ( thisCost != Cost::infinity ) {
+                                        PRINT(
+                                                std::cerr << "has finite cost." << std::endl;
+                                        )
+                                        // count one safe conversion for each value that is thrown away
+                                        thisCost.incSafe( discardedValues );
+                                        CandidateRef newCand = std::make_shared<Candidate>( 
+                                                restructureCast( cand->expr, toType, castExpr->isGenerated ), 
+                                                copy( cand->env ), move( open ), move( need ), cand->cost, 
+                                                cand->cost + thisCost );
+                                        inferParameters( newCand, matches );
+                                }
+                        }
+
+                        // select first on argument cost, then conversion cost
+                        CandidateList minArgCost = findMinCost( matches );
+                        promoteCvtCost( minArgCost );
+                        candidates = findMinCost( minArgCost );
                 }
 
@@ -297 +1064 @@
                         for ( CandidateRef & r : finder.candidates ) {
                                 addCandidate( 
-                                        *r, new ast::VirtualCastExpr{ castExpr->location, r->expr, castExpr->result } );
+                                        *r, 
+                                        new ast::VirtualCastExpr{ castExpr->location, r->expr, castExpr->result } );
                         }
                 }
 
                 void postvisit( const ast::UntypedMemberExpr * memberExpr ) {
-                        #warning unimplemented
-                        (void)memberExpr;
-                        assert(false);
+                        CandidateFinder aggFinder{ symtab, tenv };
+                        aggFinder.find( memberExpr->aggregate, ResolvMode::withAdjustment() );
+                        for ( CandidateRef & agg : aggFinder.candidates ) {
+                                // it's okay for the aggregate expression to have reference type -- cast it to the 
+                                // base type to treat the aggregate as the referenced value
+                                Cost addedCost = Cost::zero;
+                                agg->expr = referenceToRvalueConversion( agg->expr, addedCost );
+
+                                // find member of the given type
+                                if ( auto structInst = agg->expr->result.as< ast::StructInstType >() ) {
+                                        addAggMembers( 
+                                                structInst, agg->expr, *agg, addedCost, getMemberName( memberExpr ) );
+                                } else if ( auto unionInst = agg->expr->result.as< ast::UnionInstType >() ) {
+                                        addAggMembers( 
+                                                unionInst, agg->expr, *agg, addedCost, getMemberName( memberExpr ) );
+                                } else if ( auto tupleType = agg->expr->result.as< ast::TupleType >() ) {
+                                        addTupleMembers( tupleType, agg->expr, *agg, addedCost, memberExpr->member );
+                                }
+                        }
                 }
 
@@ -311 +1095 @@
                 }
 
-                void postvisit( const ast::NameExpr * variableExpr ) {
-                        #warning unimplemented
-                        (void)variableExpr;
-                        assert(false);
+                void postvisit( const ast::NameExpr * nameExpr ) {
+                        std::vector< ast::SymbolTable::IdData > declList = symtab.lookupId( nameExpr->name );
+                        PRINT( std::cerr << "nameExpr is " << nameExpr->name << std::endl; )
+                        for ( auto & data : declList ) {
+                                Cost cost = Cost::zero;
+                                ast::Expr * newExpr = data.combine( nameExpr->location, cost );
+
+                                CandidateRef newCand = std::make_shared<Candidate>(
+                                        newExpr, copy( tenv ), ast::OpenVarSet{}, ast::AssertionSet{}, Cost::zero, 
+                                        cost );
+                                PRINT(
+                                        std::cerr << "decl is ";
+                                        ast::print( std::cerr, data.id );
+                                        std::cerr << std::endl;
+                                        std::cerr << "newExpr is ";
+                                        ast::print( std::cerr, newExpr );
+                                        std::cerr << std::endl;
+                                )
+                                newCand->expr = ast::mutate_field( 
+                                        newCand->expr.get(), &ast::Expr::result, 
+                                        renameTyVars( newCand->expr->result ) );
+                                // add anonymous member interpretations whenever an aggregate value type is seen 
+                                // as a name expression
+                                addAnonConversions( newCand );
+                                candidates.emplace_back( move( newCand ) );
+                        }
                 }
 
@@ -329 +1135 @@
 
                 void postvisit( const ast::SizeofExpr * sizeofExpr ) {
-                        #warning unimplemented
-                        (void)sizeofExpr;
-                        assert(false);
+                        if ( sizeofExpr->type ) {
+                                addCandidate( 
+                                        new ast::SizeofExpr{ 
+                                                sizeofExpr->location, resolveTypeof( sizeofExpr->type, symtab ) }, 
+                                        tenv );
+                        } else {
+                                // find all candidates for the argument to sizeof
+                                CandidateFinder finder{ symtab, tenv };
+                                finder.find( sizeofExpr->expr );
+                                // find the lowest-cost candidate, otherwise ambiguous
+                                CandidateList winners = findMinCost( finder.candidates );
+                                if ( winners.size() != 1 ) {
+                                        SemanticError( 
+                                                sizeofExpr->expr.get(), "Ambiguous expression in sizeof operand: " );
+                                }
+                                // return the lowest-cost candidate
+                                CandidateRef & choice = winners.front();
+                                choice->expr = referenceToRvalueConversion( choice->expr, choice->cost );
+                                choice->cost = Cost::zero;
+                                addCandidate( *choice, new ast::SizeofExpr{ sizeofExpr->location, choice->expr } );
+                        }
                 }
 
                 void postvisit( const ast::AlignofExpr * alignofExpr ) {
-                        #warning unimplemented
-                        (void)alignofExpr;
-                        assert(false);
+                        if ( alignofExpr->type ) {
+                                addCandidate( 
+                                        new ast::AlignofExpr{ 
+                                                alignofExpr->location, resolveTypeof( alignofExpr->type, symtab ) }, 
+                                        tenv );
+                        } else {
+                                // find all candidates for the argument to alignof
+                                CandidateFinder finder{ symtab, tenv };
+                                finder.find( alignofExpr->expr );
+                                // find the lowest-cost candidate, otherwise ambiguous
+                                CandidateList winners = findMinCost( finder.candidates );
+                                if ( winners.size() != 1 ) {
+                                        SemanticError( 
+                                                alignofExpr->expr.get(), "Ambiguous expression in alignof operand: " );
+                                }
+                                // return the lowest-cost candidate
+                                CandidateRef & choice = winners.front();
+                                choice->expr = referenceToRvalueConversion( choice->expr, choice->cost );
+                                choice->cost = Cost::zero;
+                                addCandidate( 
+                                        *choice, new ast::AlignofExpr{ alignofExpr->location, choice->expr } );
+                        }
                 }
 
                 void postvisit( const ast::UntypedOffsetofExpr * offsetofExpr ) {
-                        #warning unimplemented
-                        (void)offsetofExpr;
-                        assert(false);
+                        const ast::ReferenceToType * aggInst;
+                        if (( aggInst = offsetofExpr->type.as< ast::StructInstType >() )) ;
+                        else if (( aggInst = offsetofExpr->type.as< ast::UnionInstType >() )) ;
+                        else return;
+
+                        for ( const ast::Decl * member : aggInst->lookup( offsetofExpr->member ) ) {
+                                auto dwt = strict_dynamic_cast< const ast::DeclWithType * >( member );
+                                addCandidate( 
+                                        new ast::OffsetofExpr{ offsetofExpr->location, aggInst, dwt }, tenv );
+                        }
                 }
 
@@ -376 +1226 @@
                                                 new ast::LogicalExpr{ 
                                                         logicalExpr->location, r1->expr, r2->expr, logicalExpr->isAnd },
-                                                std::move( env ), std::move( open ), std::move( need ), 
-                                                r1->cost + r2->cost );
+                                                move( env ), move( open ), move( need ), r1->cost + r2->cost );
                                 }
                         }
@@ -421 +1270 @@
                                                                 common ) 
                                                 ) {
-                                                        #warning unimplemented
-                                                        assert(false);
+                                                        // generate typed expression
+                                                        ast::ConditionalExpr * newExpr = new ast::ConditionalExpr{ 
+                                                                conditionalExpr->location, r1->expr, r2->expr, r3->expr };
+                                                        newExpr->result = common ? common : r2->expr->result;
+                                                        // convert both options to result type
+                                                        Cost cost = r1->cost + r2->cost + r3->cost;
+                                                        newExpr->arg2 = computeExpressionConversionCost( 
+                                                                newExpr->arg2, newExpr->result, symtab, env, cost );
+                                                        newExpr->arg3 = computeExpressionConversionCost(
+                                                                newExpr->arg3, newExpr->result, symtab, env, cost );
+                                                        // output candidate
+                                                        CandidateRef newCand = std::make_shared<Candidate>(
+                                                                newExpr, move( env ), move( open ), move( need ), cost );
+                                                        inferParameters( newCand, candidates );
                                                 }
                                         }
@@ -480 +1341 @@
                                                         common ) 
                                         ) {
+                                                // generate new expression
                                                 ast::RangeExpr * newExpr = 
                                                         new ast::RangeExpr{ rangeExpr->location, r1->expr, r2->expr };
                                                 newExpr->result = common ? common : r1->expr->result;
-                                                
-                                                #warning unimplemented
-                                                assert(false);
+                                                // add candidate
+                                                CandidateRef newCand = std::make_shared<Candidate>(
+                                                        newExpr, move( env ), move( open ), move( need ), 
+                                                        r1->cost + r2->cost );
+                                                inferParameters( newCand, candidates );
                                         }
                                 }
@@ -512 +1376 @@
 
                                 addCandidate(
-                                        new ast::TupleExpr{ tupleExpr->location, std::move( exprs ) }, 
-                                        std::move( env ), std::move( open ), std::move( need ), sumCost( subs ) );
+                                        new ast::TupleExpr{ tupleExpr->location, move( exprs ) }, 
+                                        move( env ), move( open ), move( need ), sumCost( subs ) );
                         }
                 }
@@ -539 +1403 @@
 
                 void postvisit( const ast::StmtExpr * stmtExpr ) {
-                        #warning unimplemented
-                        (void)stmtExpr;
-                        assert(false);
+                        addCandidate( resolveStmtExpr( stmtExpr, symtab ), tenv );
                 }
 
                 void postvisit( const ast::UntypedInitExpr * initExpr ) {
-                        #warning unimplemented
-                        (void)initExpr;
-                        assert(false);
+                        // handle each option like a cast
+                        CandidateList matches;
+                        PRINT(
+                                std::cerr << "untyped init expr: " << initExpr << std::endl;
+                        )
+                        // O(n^2) checks of d-types with e-types
+                        for ( const ast::InitAlternative & initAlt : initExpr->initAlts ) {
+                                // calculate target type
+                                const ast::Type * toType = resolveTypeof( initAlt.type, symtab );
+                                toType = SymTab::validateType( toType, symtab );
+                                toType = adjustExprType( toType, tenv, symtab );
+                                // The call to find must occur inside this loop, otherwise polymorphic return 
+                                // types are not bound to the initialization type, since return type variables are 
+                                // only open for the duration of resolving the UntypedExpr. 
+                                CandidateFinder finder{ symtab, tenv, toType };
+                                finder.find( initExpr->expr, ResolvMode::withAdjustment() );
+                                for ( CandidateRef & cand : finder.candidates ) {
+                                        ast::TypeEnvironment env{ cand->env };
+                                        ast::AssertionSet need( cand->need.begin(), cand->need.end() ), have;
+                                        ast::OpenVarSet open{ cand->open };
+
+                                        PRINT(
+                                                std::cerr << "  @ " << toType << " " << initAlt.designation << std::endl;
+                                        )
+
+                                        // It is possible that a cast can throw away some values in a multiply-valued 
+                                        // expression, e.g. cast-to-void, one value to zero. Figure out the prefix of 
+                                        // the subexpression results that are cast directly. The candidate is invalid 
+                                        // if it has fewer results than there are types to cast to.
+                                        int discardedValues = cand->expr->result->size() - toType->size();
+                                        if ( discardedValues < 0 ) continue;
+
+                                        // unification run for side-effects
+                                        unify( toType, cand->expr->result, env, need, have, open, symtab );
+                                        Cost thisCost = castCost( cand->expr->result, toType, symtab, env );
+                                        
+                                        if ( thisCost != Cost::infinity ) {
+                                                // count one safe conversion for each value that is thrown away
+                                                thisCost.incSafe( discardedValues );
+                                                CandidateRef newCand = std::make_shared<Candidate>( 
+                                                        new ast::InitExpr{ 
+                                                                initExpr->location, restructureCast( cand->expr, toType ), 
+                                                                initAlt.designation }, 
+                                                        copy( cand->env ), move( open ), move( need ), cand->cost, thisCost );
+                                                inferParameters( newCand, matches );
+                                        }
+                                }
+                        }
+
+                        // select first on argument cost, then conversion cost
+                        CandidateList minArgCost = findMinCost( matches );
+                        promoteCvtCost( minArgCost );
+                        candidates = findMinCost( minArgCost );
                 }
 
@@ -628 +1540 @@
                         cand->env.applyFree( newResult );
                         cand->expr = ast::mutate_field(
-                                cand->expr.get(), &ast::Expr::result, std::move( newResult ) );
+                                cand->expr.get(), &ast::Expr::result, move( newResult ) );
                         
                         out.emplace_back( cand );
@@ -651 +1563 @@
                 CandidateList satisfied;
                 std::vector< std::string > errors;
-                for ( auto & candidate : candidates ) {
-                        satisfyAssertions( *candidate, symtab, satisfied, errors );
+                for ( CandidateRef & candidate : candidates ) {
+                        satisfyAssertions( candidate, symtab, satisfied, errors );
                 }
 
@@ -666 +1578 @@
 
                 // reset candidates
-                candidates = std::move( satisfied );
+                candidates = move( satisfied );
         }
 
@@ -690 +1602 @@
 
                 auto oldsize = candidates.size();
-                candidates = std::move( pruned );
+                candidates = move( pruned );
 
                 PRINT(

src/ResolvExpr/CandidateFinder.hpp

@@ -27 +27 @@
 /// Data to perform expression resolution
 struct CandidateFinder {
-        CandidateList candidates;                ///< List of candidate resolutions
-        const ast::SymbolTable & symtab;         ///< Symbol table to lookup candidates
-        const ast::TypeEnvironment & env;        ///< Substitutions performed in this resolution
-        ast::ptr< ast::Type > targetType = nullptr;  ///< Target type for resolution
+        CandidateList candidates;          ///< List of candidate resolutions
+        const ast::SymbolTable & symtab;   ///< Symbol table to lookup candidates
+        const ast::TypeEnvironment & env;  ///< Substitutions performed in this resolution
+        ast::ptr< ast::Type > targetType;  ///< Target type for resolution
 
-        CandidateFinder( const ast::SymbolTable & symtab, const ast::TypeEnvironment & env )
-        : candidates(), symtab( symtab ), env( env ) {}
+        CandidateFinder( 
+                const ast::SymbolTable & symtab, const ast::TypeEnvironment & env, 
+                const ast::Type * tt = nullptr )
+        : candidates(), symtab( symtab ), env( env ), targetType( tt ) {}
 
         /// Fill candidates with feasible resolutions for `expr`
@@ -52 +54 @@
 };
 
+/// Computes conversion cost between two types
+Cost computeConversionCost( 
+        const ast::Type * argType, const ast::Type * paramType, const ast::SymbolTable & symtab, 
+        const ast::TypeEnvironment & env );
+
 } // namespace ResolvExpr
 

src/ResolvExpr/CastCost.cc

@@ -78 +78 @@
                         });
                 } else {
-                        PassVisitor<CastCost> converter( dest, indexer, env, castCost );
+                        #warning cast on castCost artifact of having two functions, remove when port done
+                        PassVisitor<CastCost> converter( 
+                                dest, indexer, env, 
+                                (Cost (*)( Type *, Type *, const SymTab::Indexer &, const TypeEnvironment & ))
+                                        castCost );
                         src->accept( converter );
                         if ( converter.pass.get_cost() == Cost::infinity ) {
@@ -125 +129 @@
                 }
         }
+
+        Cost castCost( 
+                const ast::Type * src, const ast::Type * dst, const ast::SymbolTable & symtab, 
+                const ast::TypeEnvironment & env 
+        ) {
+                #warning unimplmented
+                (void)src; (void)dst; (void)symtab; (void)env;
+                assert(false);
+                return Cost::zero;
+        }
 } // namespace ResolvExpr
 

src/ResolvExpr/ConversionCost.cc

@@ -85 +85 @@
                         });
                 } else {
-                        PassVisitor<ConversionCost> converter( dest, indexer, env, conversionCost );
+                        PassVisitor<ConversionCost> converter( 
+                                dest, indexer, env, 
+                                (Cost (*)(Type*, Type*, const SymTab::Indexer&, const TypeEnvironment&))
+                                        conversionCost );
                         src->accept( converter );
                         if ( converter.pass.get_cost() == Cost::infinity ) {
@@ -134 +137 @@
                         } else {
                                 PRINT( std::cerr << "reference to rvalue conversion" << std::endl; )
-                                PassVisitor<ConversionCost> converter( dest, indexer, env, conversionCost );
+                                PassVisitor<ConversionCost> converter( 
+                                        dest, indexer, env, 
+                                        (Cost (*)(Type*, Type*, const SymTab::Indexer&, const TypeEnvironment&))
+                                                conversionCost );
                                 src->accept( converter );
                                 return converter.pass.get_cost();
@@ -482 +488 @@
                 } // if
         }
+
+        Cost conversionCost( 
+                const ast::Type * src, const ast::Type * dst, const ast::SymbolTable & symtab, 
+                const ast::TypeEnvironment & env
+        ) {
+                #warning unimplemented
+                (void)src; (void)dst; (void)symtab; (void)env;
+                assert(false);
+                return Cost::zero;
+        }
 } // namespace ResolvExpr
 

src/ResolvExpr/PolyCost.cc

@@ -9 +9 @@
 // Author           : Richard C. Bilson
 // Created On       : Sun May 17 09:50:12 2015
-// Last Modified By : Peter A. Buhr
-// Last Modified On : Sun May 17 09:52:02 2015
-// Update Count     : 3
+// Last Modified By : Andrew Beach
+// Last Modified On : Wed Jun 19 10:45:00 2019
+// Update Count     : 4
 //
 
+#include "AST/SymbolTable.hpp"
+#include "AST/Type.hpp"
+#include "AST/TypeEnvironment.hpp"
 #include "Common/PassVisitor.h"
 #include "SymTab/Indexer.h"   // for Indexer
@@ -54 +57 @@
         }
 
+// TODO: When the old PolyCost is torn out get rid of the _new suffix.
+struct PolyCost_new {
+        int result;
+        const ast::SymbolTable &symtab;
+        const ast::TypeEnvironment &env_;
+
+        PolyCost_new( const ast::SymbolTable & symtab, const ast::TypeEnvironment & env ) :
+                result( 0 ), symtab( symtab ), env_( env ) {}
+
+        void previsit( const ast::TypeInstType * type ) {
+                if ( const ast::EqvClass * eqv = env_.lookup( type->name ) ) /* && */ if ( eqv->bound ) {
+                        if ( const ast::TypeInstType * otherType = eqv->bound.as< ast::TypeInstType >() ) {
+                                if ( symtab.lookupType( otherType->name ) ) {
+                                        // Bound to opaque type.
+                                        result += 1;
+                                }
+                        } else {
+                                // Bound to concrete type.
+                                result += 1;
+                        }
+                }
+        }
+};
+
+int polyCost(
+        const ast::Type * type, const ast::SymbolTable & symtab, const ast::TypeEnvironment & env
+) {
+        ast::Pass<PolyCost_new> costing( symtab, env );
+        type->accept( costing );
+        return costing.pass.result;
+}
+
 } // namespace ResolvExpr
 

src/ResolvExpr/RenameVars.cc

@@ -96 +96 @@
                 }
         } // namespace
+
+        const ast::Type * renameTyVars( const ast::Type * t ) {
+                #warning unimplemented; make sure resetTyVarRenaming() updated when implemented
+                (void)t;
+                assert(false);
+                return t;
+        }
 } // namespace ResolvExpr
 

src/ResolvExpr/RenameVars.h

@@ -23 +23 @@
 #include "SynTree/Visitor.h"  // for Visitor
 
+namespace ast {
+        class Type;
+}
+
 namespace ResolvExpr {
         /// Provides a consistent renaming of forall type names in a hierarchy by prefixing them with a unique "level" ID
         void renameTyVars( Type * );
+        const ast::Type * renameTyVars( const ast::Type * );
 
         /// resets internal state of renamer to avoid overflow

src/ResolvExpr/ResolveAssertions.cc

@@ -186 +186 @@
         using InferCache = std::unordered_map< UniqueId, InferredParams >;
 
+        /// Lexicographically-ordered vector of costs
+        using CostVec = std::vector< Cost >;
+
+        int compare( const CostVec & a, const CostVec & b ) {
+                unsigned i = 0;
+                do {
+                        // lex-compare where shorter one is less
+                        if ( i == a.size() ) {
+                                return i == b.size() ? 0 : -1;
+                        }
+                        if ( i == b.size() /* && i < a.size() */ ) return 1;
+                        
+                        int c = a[i].compare( b[i] );
+                        if ( c != 0 ) return c;
+                } while ( ++i );
+                assert(!"unreachable");
+        }
+
+        bool operator< ( const CostVec & a, const CostVec & b ) { return compare( a, b ) < 0; }
+
         /// Flag for state iteration
         enum IterateFlag { IterateState };
@@ -196 +216 @@
                 DeferList deferred;        ///< Deferred matches
                 InferCache inferred;       ///< Cache of already-inferred parameters
+                CostVec costs;             ///< Costs of recursive assertion satisfaction for disambiguation
                 SymTab::Indexer& indexer;  ///< Name lookup (depends on previous assertions)
 
                 /// Initial resolution state for an alternative
                 ResnState( Alternative& a, SymTab::Indexer& indexer )
-                : alt(a), need(), newNeed(), deferred(), inferred(), indexer(indexer) {
+                : alt(a), need(), newNeed(), deferred(), inferred(), costs{ Cost::zero }, indexer(indexer) {
                         need.swap( a.need );
                 }
@@ -207 +228 @@
                 ResnState( ResnState&& o, IterateFlag )
                 : alt(std::move(o.alt)), need(o.newNeed.begin(), o.newNeed.end()), newNeed(), deferred(),
-                  inferred(std::move(o.inferred)), indexer(o.indexer) {}
+                  inferred(std::move(o.inferred)), costs(o.costs), indexer(o.indexer) {
+                        costs.emplace_back( Cost::zero );
+                }
         };
 
@@ -336 +359 @@
         };
 
-        void finalizeAssertions( Alternative& alt, InferCache& inferred, AltList& out ) {
-                PassVisitor<InferMatcher> matcher{ inferred };
-                alt.expr = alt.expr->acceptMutator( matcher );
-                out.emplace_back( alt );
+        /// Map of alternative return types to recursive assertion satisfaction costs
+        using PruneMap = std::unordered_map<std::string, CostVec>;
+
+        /// Gets the pruning key for an alternative
+        std::string pruneKey( const Alternative & alt ) {
+                Type* resType = alt.expr->result->clone();
+                alt.env.apply( resType );
+                std::string resKey = SymTab::Mangler::mangleType( resType );
+                delete resType;
+                return std::move( resKey );
+        }
+        
+        /// Replace resnSlots with inferParams and add alternative to output list, if meets pruning 
+        /// threshold.
+        void finalizeAssertions( ResnState& resn, PruneMap & pruneThresholds, AltList& out ) {
+                // prune if cheaper alternative for same key has already been generated
+                std::string resKey = pruneKey( resn.alt );
+                auto it = pruneThresholds.find( resKey );
+                if ( it != pruneThresholds.end() ) {
+                        if ( it->second < resn.costs ) return;
+                } else {
+                        pruneThresholds.emplace_hint( it, resKey, resn.costs );
+                }
+
+                // replace resolution slots with inferred params, add to output
+                PassVisitor<InferMatcher> matcher{ resn.inferred };
+                resn.alt.expr = resn.alt.expr->acceptMutator( matcher );
+                out.emplace_back( resn.alt );
         }
 
@@ -359 +406 @@
                 ResnList resns{ ResnState{ alt, root_indexer } };
                 ResnList new_resns{};
+                
+                // Pruning thresholds by result type of the output alternatives.
+                // Alternatives *should* be generated in sorted order, so no need to retroactively prune
+                PruneMap thresholds;
 
                 // resolve assertions in breadth-first-order up to a limited number of levels deep
@@ -364 +415 @@
                         // scan over all mutually-compatible resolutions
                         for ( auto& resn : resns ) {
+                                // stop this branch if already found a better option
+                                auto it = thresholds.find( pruneKey( resn.alt ) );
+                                if ( it != thresholds.end() && it->second < resn.costs ) goto nextResn;
+
                                 // make initial pass at matching assertions
                                 for ( auto& assn : resn.need ) {
@@ -383 +438 @@
                                         // either add successful match or push back next state
                                         if ( resn.newNeed.empty() ) {
-                                                finalizeAssertions( resn.alt, resn.inferred, out );
+                                                finalizeAssertions( resn, thresholds, out );
                                         } else {
                                                 new_resns.emplace_back( std::move(resn), IterateState );
@@ -420 +475 @@
                                                 goto nextResn;
                                         }
-                                        // sort by cost
+                                        // sort by cost for overall pruning
                                         CandidateCost coster{ resn.indexer };
                                         std::sort( compatible.begin(), compatible.end(), coster );
 
-                                        // keep map of detected options
-                                        std::unordered_map<std::string, Cost> found;
                                         for ( auto& compat : compatible ) {
-                                                // filter by environment-adjusted result type, keep only cheapest option
-                                                Type* resType = alt.expr->result->clone();
-                                                compat.env.apply( resType );
-                                                // skip if cheaper alternative already processed with same result type
-                                                Cost resCost = coster.get( compat );
-                                                auto it = found.emplace( SymTab::Mangler::mangleType( resType ), resCost );
-                                                delete resType;
-                                                if ( it.second == false && it.first->second < resCost ) continue;
-
-                                                // proceed with resolution step
                                                 ResnState new_resn = resn;
 
@@ -452 +495 @@
                                                 new_resn.alt.openVars = std::move(compat.openVars);
 
+                                                // mark cost of this path
+                                                new_resn.costs.back() += compat.cost;
+
                                                 // either add sucessful match or push back next state
                                                 if ( new_resn.newNeed.empty() ) {
-                                                        finalizeAssertions( new_resn.alt, new_resn.inferred, out );
+                                                        finalizeAssertions( new_resn, thresholds, out );
                                                 } else {
                                                         new_resns.emplace_back( std::move(new_resn), IterateState );

src/ResolvExpr/ResolveTypeof.cc

@@ -107 +107 @@
                 return newType;
         }
+
+        const ast::Type * resolveTypeof( const ast::Type * type , const ast::SymbolTable & symtab ) {
+                #warning unimplemented
+                (void)type; (void)symtab;
+                assert(false);
+                return nullptr;
+        }
 } // namespace ResolvExpr
 

src/ResolvExpr/ResolveTypeof.h

@@ -20 +20 @@
 class Indexer;
 }  // namespace SymTab
+namespace ast {
+        class Type;
+        class SymbolTable;
+}
 
 namespace ResolvExpr {
         Type *resolveTypeof( Type*, const SymTab::Indexer &indexer );
+        const ast::Type * resolveTypeof( const ast::Type *, const ast::SymbolTable & );
 } // namespace ResolvExpr
 

src/ResolvExpr/Resolver.cc

@@ -1249 +1249 @@
 
         void resolve( std::list< ast::ptr<ast::Decl> >& translationUnit ) {
-                ast::Pass<Resolver_new> resolver;
+                ast::Pass< Resolver_new > resolver;
                 accept_all( translationUnit, resolver );
+        }
+
+        ast::ptr< ast::Expr > resolveStmtExpr( 
+                const ast::StmtExpr * stmtExpr, const ast::SymbolTable & symtab 
+        ) {
+                assert( stmtExpr );
+                ast::Pass< Resolver_new > resolver{ symtab };
+                ast::ptr< ast::Expr > ret = stmtExpr;
+                ret = ret->accept( resolver );
+                strict_dynamic_cast< ast::StmtExpr * >( ret.get_and_mutate() )->computeResult();
+                return ret;
         }
 

src/ResolvExpr/Resolver.h

@@ -31 +31 @@
         class Decl;
         class DeletedExpr;
+        class StmtExpr;
         class SymbolTable;
         class TypeEnvironment;
@@ -58 +59 @@
         ast::ptr< ast::Expr > resolveInVoidContext(
                 const ast::Expr * expr, const ast::SymbolTable & symtab, ast::TypeEnvironment & env );
+        /// Resolves a statement expression
+        ast::ptr< ast::Expr > resolveStmtExpr( 
+                const ast::StmtExpr * stmtExpr, const ast::SymbolTable & symtab );
 } // namespace ResolvExpr
 

src/ResolvExpr/SatisfyAssertions.cpp

@@ -16 +16 @@
 #include "SatisfyAssertions.hpp"
 
+#include <algorithm>
 #include <cassert>
+#include <sstream>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "Candidate.hpp"
+#include "CandidateFinder.hpp"
+#include "Cost.h"
+#include "RenameVars.h"
+#include "typeops.h"
+#include "Unify.h"
+#include "AST/Decl.hpp"
+#include "AST/Expr.hpp"
+#include "AST/Node.hpp"
+#include "AST/Pass.hpp"
+#include "AST/Print.hpp"
+#include "AST/SymbolTable.hpp"
+#include "AST/TypeEnvironment.hpp"
+#include "Common/FilterCombos.h"
+#include "Common/Indenter.h"
+#include "GenPoly/GenPoly.h"
+#include "SymTab/Mangler.h"
 
 namespace ResolvExpr {
 
+// in CandidateFinder.cpp; unique ID for assertion satisfaction
+extern UniqueId globalResnSlot;
+
+namespace {
+        /// Post-unification assertion satisfaction candidate
+        struct AssnCandidate {
+                ast::SymbolTable::IdData cdata;  ///< Satisfying declaration
+                ast::ptr< ast::Type > adjType;   ///< Satisfying type
+                ast::TypeEnvironment env;        ///< Post-unification environment
+                ast::AssertionSet have;          ///< Post-unification have-set
+                ast::AssertionSet need;          ///< Post-unification need-set
+                ast::OpenVarSet open;            ///< Post-unification open-var-set
+                ast::UniqueId resnSlot;          ///< Slot for any recursive assertion IDs
+
+                AssnCandidate( 
+                        const ast::SymbolTable::IdData c, const ast::Type * at, ast::TypeEnvironment && e, 
+                        ast::AssertionSet && h, ast::AssertionSet && n, ast::OpenVarSet && o, ast::UniqueId rs )
+                : cdata( c ), adjType( at ), env( std::move( e ) ), have( std::move( h ) ), 
+                  need( std::move( n ) ), open( std::move( o ) ), resnSlot( rs ) {}
+        };
+
+        /// List of assertion satisfaction candidates
+        using AssnCandidateList = std::vector< AssnCandidate >;
+
+        /// Reference to a single deferred item
+        struct DeferRef {
+                const ast::DeclWithType * decl;
+                const ast::AssertionSetValue & info;
+                const AssnCandidate & match;
+        };
+        
+        /// Wrapper for the deferred items from a single assertion satisfaction. 
+        /// Acts like an indexed list of DeferRef
+        struct DeferItem {
+                const ast::DeclWithType * decl;
+                const ast::AssertionSetValue & info;
+                AssnCandidateList matches;
+
+                DeferItem( 
+                        const ast::DeclWithType * d, const ast::AssertionSetValue & i, AssnCandidateList && ms )
+                : decl( d ), info( i ), matches( std::move( ms ) ) {}
+
+                bool empty() const { return matches.empty(); }
+
+                AssnCandidateList::size_type size() const { return matches.size(); }
+
+                DeferRef operator[] ( unsigned i ) const { return { decl, info, matches[i] }; }
+        };
+
+        /// List of deferred satisfaction items
+        using DeferList = std::vector< DeferItem >;
+
+        /// Set of assertion satisfactions, grouped by resolution ID
+        using InferCache = std::unordered_map< ast::UniqueId, ast::InferredParams >;
+
+        /// Lexicographically-ordered vector of costs.
+        /// Lexicographic order comes from default operator< on std::vector.
+        using CostVec = std::vector< Cost >;
+
+        /// Flag for state iteration
+        enum IterateFlag { IterateState };
+
+        /// Intermediate state for satisfying a set of assertions
+        struct SatState {
+                CandidateRef cand;          ///< Candidate assertion is rooted on
+                ast::AssertionList need;    ///< Assertions to find
+                ast::AssertionSet newNeed;  ///< Recursive assertions from current satisfied assertions
+                DeferList deferred;         ///< Deferred matches
+                InferCache inferred;        ///< Cache of already-inferred assertions
+                CostVec costs;              ///< Disambiguating costs of recursive assertion satisfaction
+                ast::SymbolTable symtab;    ///< Name lookup (depends on previous assertions)
+
+                /// Initial satisfaction state for a candidate
+                SatState( CandidateRef & c, const ast::SymbolTable & syms )
+                : cand( c ), need(), newNeed(), deferred(), inferred(), costs{ Cost::zero }, 
+                  symtab( syms ) { need.swap( c->need ); }
+                
+                /// Update satisfaction state for next step after previous state
+                SatState( SatState && o, IterateFlag )
+                : cand( std::move( o.cand ) ), need( o.newNeed.begin(), o.newNeed.end() ), newNeed(), 
+                  deferred(), inferred( std::move( o.inferred ) ), costs( std::move( o.costs ) ), 
+                  symtab( o.symtab ) { costs.emplace_back( Cost::zero ); }
+                
+                /// Field-wise next step constructor
+                SatState(
+                        CandidateRef && c, ast::AssertionSet && nn, InferCache && i, CostVec && cs, 
+                        ast::SymbolTable && syms )
+                : cand( std::move( c ) ), need( nn.begin(), nn.end() ), newNeed(), deferred(), 
+                  inferred( std::move( i ) ), costs( std::move( cs ) ), symtab( std::move( syms ) )
+                  { costs.emplace_back( Cost::zero ); }
+        };
+
+        /// Adds a captured assertion to the symbol table
+        void addToSymbolTable( const ast::AssertionSet & have, ast::SymbolTable & symtab ) {
+                for ( auto & i : have ) {
+                        if ( i.second.isUsed ) { symtab.addId( i.first ); }
+                }
+        }
+
+        /// Binds a single assertion, updating satisfaction state
+        void bindAssertion( 
+                const ast::DeclWithType * decl, const ast::AssertionSetValue & info, CandidateRef & cand, 
+                AssnCandidate & match, InferCache & inferred
+        ) {
+                const ast::DeclWithType * candidate = match.cdata.id;
+                assertf( candidate->uniqueId, 
+                        "Assertion candidate does not have a unique ID: %s", toString( candidate ).c_str() );
+                
+                ast::Expr * varExpr = match.cdata.combine( cand->expr->location, cand->cvtCost );
+                varExpr->result = match.adjType;
+                if ( match.resnSlot ) { varExpr->inferred.resnSlots().emplace_back( match.resnSlot ); }
+
+                // place newly-inferred assertion in proper location in cache
+                inferred[ info.resnSlot ][ decl->uniqueId ] = ast::ParamEntry{
+                        candidate->uniqueId, candidate, match.adjType, decl->get_type(), varExpr };
+        }
+
+        /// Satisfy a single assertion
+        bool satisfyAssertion( ast::AssertionList::value_type & assn, SatState & sat ) {
+                // skip unused assertions
+                if ( ! assn.second.isUsed ) return true;
+
+                // find candidates that unify with the desired type
+                AssnCandidateList matches;
+                for ( const ast::SymbolTable::IdData & cdata : sat.symtab.lookupId( assn.first->name ) ) {
+                        const ast::DeclWithType * candidate = cdata.id;
+
+                        // build independent unification context for candidate
+                        ast::AssertionSet have, newNeed;
+                        ast::TypeEnvironment newEnv{ sat.cand->env };
+                        ast::OpenVarSet newOpen{ sat.cand->open };
+                        ast::ptr< ast::Type > toType = assn.first->get_type();
+                        ast::ptr< ast::Type > adjType = 
+                                renameTyVars( adjustExprType( candidate->get_type(), newEnv, sat.symtab ) );
+
+                        // only keep candidates which unify
+                        if ( unify( toType, adjType, newEnv, newNeed, have, newOpen, sat.symtab ) ) {
+                                // set up binding slot for recursive assertions
+                                ast::UniqueId crntResnSlot = 0;
+                                if ( ! newNeed.empty() ) {
+                                        crntResnSlot = ++globalResnSlot;
+                                        for ( auto & a : newNeed ) { a.second.resnSlot = crntResnSlot; }
+                                }
+
+                                matches.emplace_back( 
+                                        cdata, adjType, std::move( newEnv ), std::move( newNeed ), std::move( have ), 
+                                        std::move( newOpen ), crntResnSlot );
+                        }
+                }
+
+                // break if no satisfying match
+                if ( matches.empty() ) return false;
+
+                // defer if too many satisfying matches
+                if ( matches.size() > 1 ) {
+                        sat.deferred.emplace_back( assn.first, assn.second, std::move( matches ) );
+                        return true;
+                }
+
+                // otherwise bind unique match in ongoing scope
+                AssnCandidate & match = matches.front();
+                addToSymbolTable( match.have, sat.symtab );
+                sat.newNeed.insert( match.need.begin(), match.need.end() );
+                sat.cand->env = std::move( match.env );
+                sat.cand->open = std::move( match.open );
+
+                bindAssertion( assn.first, assn.second, sat.cand, match, sat.inferred );
+                return true;
+        }
+
+        /// Map of candidate return types to recursive assertion satisfaction costs
+        using PruneMap = std::unordered_map< std::string, CostVec >;
+
+        /// Gets the pruning key for a candidate (derived from environment-adjusted return type)
+        std::string pruneKey( const Candidate & cand ) {
+                ast::ptr< ast::Type > resType = cand.expr->result;
+                cand.env.apply( resType );
+                return Mangle::mangle( resType, Mangle::typeMode() );
+        }
+
+        /// Associates inferred parameters with an expression
+        struct InferMatcher final {
+                InferCache & inferred;
+
+                InferMatcher( InferCache & inferred ) : inferred( inferred ) {}
+
+                const ast::Expr * postmutate( const ast::Expr * expr ) {
+                        // Skip if no slots to find
+                        if ( expr->inferred.mode != ast::Expr::InferUnion::Slots ) return expr;
+
+                        // find inferred parameters for resolution slots
+                        ast::InferredParams newInferred;
+                        for ( UniqueId slot : expr->inferred.resnSlots() ) {
+                                // fail if no matching assertions found
+                                auto it = inferred.find( slot );
+                                if ( it == inferred.end() ) {
+                                        assert(!"missing assertion");
+                                }
+
+                                // place inferred parameters into new map
+                                for ( auto & entry : it->second ) {
+                                        // recurse on inferParams of resolved expressions
+                                        entry.second.expr = postmutate( entry.second.expr );
+                                        auto res = newInferred.emplace( entry );
+                                        assert( res.second && "all assertions newly placed" );
+                                }
+                        }
+
+                        ast::Expr * ret = mutate( expr );
+                        ret->inferred.set_inferParams( std::move( newInferred ) );
+                        return ret;
+                }
+        };
+
+        /// Replace ResnSlots with InferParams and add alternative to output list, if it meets pruning 
+        /// threshold.
+        void finalizeAssertions( 
+                CandidateRef & cand, InferCache & inferred, PruneMap & thresholds, CostVec && costs, 
+                CandidateList & out 
+        ) {
+                // prune if cheaper alternative for same key has already been generated
+                std::string key = pruneKey( *cand );
+                auto it = thresholds.find( key );
+                if ( it != thresholds.end() ) {
+                        if ( it->second < costs ) return;
+                } else {
+                        thresholds.emplace_hint( it, key, std::move( costs ) );
+                }
+
+                // replace resolution slots with inferred parameters, add to output
+                ast::Pass< InferMatcher > matcher{ inferred };
+                cand->expr = cand->expr->accept( matcher );
+                out.emplace_back( cand );
+        }
+
+        /// Combo iterator that combines candidates into an output list, merging their environments. 
+        /// Rejects an appended candidate if environments cannot be merged. See `Common/FilterCombos.h` 
+        /// for description of "combo iterator".
+        class CandidateEnvMerger {
+                /// Current list of merged candidates
+                std::vector< DeferRef > crnt;
+                /// Stack of environments to support backtracking
+                std::vector< ast::TypeEnvironment > envs;
+                /// Stack of open variables to support backtracking
+                std::vector< ast::OpenVarSet > opens;
+                /// Symbol table to use for merges
+                const ast::SymbolTable & symtab;
+
+        public:
+                /// The merged environment/open variables and the list of candidates
+                struct OutType {
+                        ast::TypeEnvironment env;
+                        ast::OpenVarSet open;
+                        std::vector< DeferRef > assns;
+                        Cost cost;
+
+                        OutType( 
+                                const ast::TypeEnvironment & e, const ast::OpenVarSet & o, 
+                                const std::vector< DeferRef > & as, const ast::SymbolTable & symtab )
+                        : env( e ), open( o ), assns( as ), cost( Cost::zero ) {
+                                // compute combined conversion cost
+                                for ( const DeferRef & assn : assns ) {
+                                        // compute conversion cost from satisfying decl to assertion
+                                        cost += computeConversionCost( 
+                                                assn.match.adjType, assn.decl->get_type(), symtab, env );
+                                        
+                                        // mark vars+specialization on function-type assertions
+                                        const ast::FunctionType * func = 
+                                                GenPoly::getFunctionType( assn.match.cdata.id->get_type() );
+                                        if ( ! func ) continue;
+
+                                        for ( const ast::DeclWithType * param : func->params ) {
+                                                cost.decSpec( specCost( param->get_type() ) );
+                                        }
+                                        
+                                        cost.incVar( func->forall.size() );
+                                        
+                                        for ( const ast::TypeDecl * td : func->forall ) {
+                                                cost.decSpec( td->assertions.size() );
+                                        }
+                                }
+                        }
+
+                        bool operator< ( const OutType & o ) const { return cost < o.cost; }
+                };
+
+                CandidateEnvMerger( 
+                        const ast::TypeEnvironment & env, const ast::OpenVarSet & open, 
+                        const ast::SymbolTable & syms )
+                : crnt(), envs{ env }, opens{ open }, symtab( syms ) {}
+
+                bool append( DeferRef i ) {
+                        ast::TypeEnvironment env = envs.back();
+                        ast::OpenVarSet open = opens.back();
+                        mergeOpenVars( open, i.match.open );
+
+                        if ( ! env.combine( i.match.env, open, symtab ) ) return false;
+
+                        crnt.emplace_back( i );
+                        envs.emplace_back( std::move( env ) );
+                        opens.emplace_back( std::move( open ) );
+                        return true;
+                }
+
+                void backtrack() {
+                        crnt.pop_back();
+                        envs.pop_back();
+                        opens.pop_back();
+                }
+
+                OutType finalize() { return { envs.back(), opens.back(), crnt, symtab }; }
+        };
+
+        /// Limit to depth of recursion of assertion satisfaction
+        static const int recursionLimit = 4;
+        /// Maximum number of simultaneously-deferred assertions to attempt concurrent satisfaction of
+        static const int deferLimit = 10;
+} // anonymous namespace
+
 void satisfyAssertions( 
-        Candidate & alt, const ast::SymbolTable & symtab, CandidateList & out, 
+        CandidateRef & cand, const ast::SymbolTable & symtab, CandidateList & out, 
         std::vector<std::string> & errors
 ) {
-        #warning unimplemented
-        (void)alt; (void)symtab; (void)out; (void)errors;
-        assert(false);
+        // finish early if no assertions to satisfy
+        if ( cand->need.empty() ) {
+                out.emplace_back( cand );
+                return;
+        }
+
+        // build list of possible combinations of satisfying declarations
+        std::vector< SatState > sats{ SatState{ cand, symtab } };
+        std::vector< SatState > nextSats{};
+
+        // pruning thresholds by result type of output candidates.
+        // Candidates *should* be generated in sorted order, so no need to retroactively prune
+        PruneMap thresholds;
+
+        // satisfy assertions in breadth-first order over the recursion tree of assertion satisfaction.
+        // Stop recursion at a limited number of levels deep to avoid infinite loops.
+        for ( unsigned level = 0; level < recursionLimit; ++level ) {
+                // for each current mutually-compatible set of assertions
+                for ( SatState & sat : sats ) {
+                        // stop this branch if a better option is already found
+                        auto it = thresholds.find( pruneKey( *sat.cand ) );
+                        if ( it != thresholds.end() && it->second < sat.costs ) goto nextSat;
+
+                        // make initial pass at matching assertions
+                        for ( auto & assn : sat.need ) {
+                                // fail early if any assertion is not satisfiable
+                                if ( ! satisfyAssertion( assn, sat ) ) {
+                                        Indenter tabs{ 3 };
+                                        std::ostringstream ss;
+                                        ss << tabs << "Unsatisfiable alternative:\n";
+                                        print( ss, *sat.cand, ++tabs );
+                                        ss << (tabs-1) << "Could not satisfy assertion:\n";
+                                        ast::print( ss, assn.first, tabs );
+
+                                        errors.emplace_back( ss.str() );
+                                        goto nextSat;
+                                }
+                        }
+
+                        if ( sat.deferred.empty() ) {
+                                // either add successful match or push back next state
+                                if ( sat.newNeed.empty() ) {
+                                        finalizeAssertions( 
+                                                sat.cand, sat.inferred, thresholds, std::move( sat.costs ), out );
+                                } else {
+                                        nextSats.emplace_back( std::move( sat ), IterateState );
+                                }
+                        } else if ( sat.deferred.size() > deferLimit ) {
+                                // too many deferred assertions to attempt mutual compatibility
+                                Indenter tabs{ 3 };
+                                std::ostringstream ss;
+                                ss << tabs << "Unsatisfiable alternative:\n";
+                                print( ss, *sat.cand, ++tabs );
+                                ss << (tabs-1) << "Too many non-unique satisfying assignments for assertions:\n";
+                                for ( const auto & d : sat.deferred ) {
+                                        ast::print( ss, d.decl, tabs );
+                                }
+
+                                errors.emplace_back( ss.str() );
+                                goto nextSat;
+                        } else {
+                                // combine deferred assertions by mutual compatibility
+                                std::vector< CandidateEnvMerger::OutType > compatible = filterCombos(
+                                        sat.deferred, CandidateEnvMerger{ sat.cand->env, sat.cand->open, sat.symtab } );
+                                
+                                // fail early if no mutually-compatible assertion satisfaction
+                                if ( compatible.empty() ) {
+                                        Indenter tabs{ 3 };
+                                        std::ostringstream ss;
+                                        ss << tabs << "Unsatisfiable alternative:\n";
+                                        print( ss, *sat.cand, ++tabs );
+                                        ss << (tabs-1) << "No mutually-compatible satisfaction for assertions:\n";
+                                        for ( const auto& d : sat.deferred ) {
+                                                ast::print( ss, d.decl, tabs );
+                                        }
+
+                                        errors.emplace_back( ss.str() );
+                                        goto nextSat;
+                                }
+
+                                // sort by cost (for overall pruning order)
+                                std::sort( compatible.begin(), compatible.end() );
+
+                                // process mutually-compatible combinations
+                                for ( auto & compat : compatible ) {
+                                        // set up next satisfaction state
+                                        CandidateRef nextCand = std::make_shared<Candidate>(
+                                                sat.cand->expr, std::move( compat.env ), std::move( compat.open ), 
+                                                ast::AssertionSet{} /* need moved into satisfaction state */,
+                                                sat.cand->cost, sat.cand->cvtCost );
+
+                                        ast::AssertionSet nextNewNeed{ sat.newNeed };
+                                        InferCache nextInferred{ sat.inferred };
+                                        
+                                        CostVec nextCosts{ sat.costs };
+                                        nextCosts.back() += compat.cost;
+                                                                
+                                        ast::SymbolTable nextSymtab{ sat.symtab };
+
+                                        // add compatible assertions to new satisfaction state
+                                        for ( DeferRef r : compat.assns ) {
+                                                AssnCandidate match = r.match;
+                                                addToSymbolTable( match.have, nextSymtab );
+                                                nextNewNeed.insert( match.need.begin(), match.need.end() );
+
+                                                bindAssertion( r.decl, r.info, nextCand, match, nextInferred );
+                                        }
+
+                                        // either add successful match or push back next state
+                                        if ( nextNewNeed.empty() ) {
+                                                finalizeAssertions( 
+                                                        nextCand, nextInferred, thresholds, std::move( nextCosts ), out );
+                                        } else {
+                                                nextSats.emplace_back( 
+                                                        std::move( nextCand ), std::move( nextNewNeed ), 
+                                                        std::move( nextInferred ), std::move( nextCosts ), 
+                                                        std::move( nextSymtab ) );
+                                        }
+                                }
+                        }
+                nextSat:; }
+
+                // finish or reset for next round
+                if ( nextSats.empty() ) return;
+                sats.swap( nextSats );
+                nextSats.clear();
+        }
+        
+        // exceeded recursion limit if reaches here
+        if ( out.empty() ) {
+                SemanticError( cand->expr->location, "Too many recursive assertions" );
+        }
 }
 

src/ResolvExpr/SatisfyAssertions.hpp

@@ -29 +29 @@
 /// Recursively satisfies all assertions provided in a candidate; returns true if succeeds
 void satisfyAssertions( 
-        Candidate & alt, const ast::SymbolTable & symtab, CandidateList & out, 
+        CandidateRef & cand, const ast::SymbolTable & symtab, CandidateList & out, 
         std::vector<std::string> & errors );
 

src/ResolvExpr/SpecCost.cc

@@ -9 +9 @@
 // Author           : Aaron B. Moss
 // Created On       : Tue Oct 02 15:50:00 2018
-// Last Modified By : Aaron B. Moss
-// Last Modified On : Tue Oct 02 15:50:00 2018
-// Update Count     : 1
+// Last Modified By : Andrew Beach
+// Last Modified On : Wed Jun 19 10:43:00 2019
+// Update Count     : 2
 //
 
 #include <limits>
 #include <list>
-
+#include <type_traits>
+
+#include "AST/Pass.hpp"
+#include "AST/Type.hpp"
 #include "Common/PassVisitor.h"
 #include "SynTree/Declaration.h"
@@ -61 +64 @@
                         visit_children = false;
                 }
-        
+
         private:
                 // returns minimum non-negative count + 1 over type parameters (-1 if none such)
@@ -80 +83 @@
                         visit_children = false;
                 }
-                
+
                 // look for polymorphic parameters
                 void previsit(UnionInstType* uty) {
@@ -111 +114 @@
                 return counter.pass.get_count();
         }
+
+namespace {
+        /// The specialization counter inner class.
+        class SpecCounter : public ast::WithShortCircuiting, public ast::WithVisitorRef<SpecCounter> {
+                int count = -1;  ///< specialization count (-1 for none)
+
+                // Converts the max value to -1 (none), otherwise increments the value.
+                static int toNoneOrInc( int value ) {
+                        assert( 0 <= value );
+                        return value < std::numeric_limits<int>::max() ? value + 1 : -1;
+                }
+
+                template<typename T> using MapperT =
+                        typename std::add_pointer<ast::Type const *(typename T::value_type const &)>::type;
+
+                // Update the minimum to the new lowest non-none value.
+                template<typename T>
+                void updateMinimumPresent( int & minimum, const T & list, MapperT<T> mapper ) {
+                        for ( const auto & node : list ) {
+                                count = -1;
+                                mapper( node )->accept( *visitor );
+                                if ( count != -1 && count < minimum ) minimum = count;
+                        }
+                }
+
+                // Returns minimum non-negative count + 1 over type parameters (-1 if none such).
+                template<typename T>
+                int minimumPresent( const T & list, MapperT<T> mapper ) {
+                        int minCount = std::numeric_limits<int>::max();
+                        updateMinimumPresent( minCount, list, mapper );
+                        return toNoneOrInc( minCount );
+                }
+
+                // The three mappers:
+                static const ast::Type * decl_type( const ast::ptr< ast::DeclWithType > & decl ) {
+                        return decl->get_type();
+                }
+                static const ast::Type * expr_result( const ast::ptr< ast::Expr > & expr ) {
+                        return expr->result;
+                }
+                static const ast::Type * type_deref( const ast::ptr< ast::Type > & type ) {
+                        return type.get();
+                }
+
+        public:
+                int get_count() const { return 0 <= count ? count : 0; }
+
+                // Mark specialization of base type.
+                void postvisit( const ast::PointerType * ) { if ( count >= 0 ) ++count; }
+                void postvisit( const ast::ArrayType * ) { if ( count >= 0 ) ++count; }
+                void postvisit( const ast::ReferenceType * ) { if ( count >= 0 ) ++count; }
+
+                // Use the minimal specialization value over returns and params.
+                void previsit( const ast::FunctionType * fty ) {
+                        int minCount = std::numeric_limits<int>::max();
+                        updateMinimumPresent( minCount, fty->params, decl_type );
+                        updateMinimumPresent( minCount, fty->returns, decl_type );
+                        // Add another level to minCount if set.
+                        count = toNoneOrInc( minCount );
+                        // We have already visited children.
+                        visit_children = false;
+                }
+
+                // Look for polymorphic parameters.
+                void previsit( const ast::StructInstType * sty ) {
+                        count = minimumPresent( sty->params, expr_result );
+                        visit_children = false;
+                }
+
+                // Look for polymorphic parameters.
+                void previsit( const ast::UnionInstType * uty ) {
+                        count = minimumPresent( uty->params, expr_result );
+                        visit_children = false;
+                }
+
+                // Note polymorphic type (which may be specialized).
+                // xxx - maybe account for open/closed type variables
+                void postvisit( const ast::TypeInstType * ) { count = 0; }
+
+                // Use the minimal specialization over elements.
+                // xxx - maybe don't increment, tuple flattening doesn't necessarily specialize
+                void previsit( const ast::TupleType * tty ) {
+                        count = minimumPresent( tty->types, type_deref );
+                        visit_children = false;
+                }
+        };
+
+} // namespace
+
+int specCost( const ast::Type * type ) {
+        if ( nullptr == type ) {
+                return 0;
+        }
+        ast::Pass<SpecCounter> counter;
+        type->accept( *counter.pass.visitor );
+        return counter.pass.get_count();
+}
+
 } // namespace ResolvExpr
 

src/ResolvExpr/typeops.h

@@ -78 +78 @@
         // in CastCost.cc
         Cost castCost( Type *src, Type *dest, const SymTab::Indexer &indexer, const TypeEnvironment &env );
+        Cost castCost( 
+                const ast::Type * src, const ast::Type * dst, const ast::SymbolTable & symtab, 
+                const ast::TypeEnvironment & env );
 
         // in ConversionCost.cc
         Cost conversionCost( Type *src, Type *dest, const SymTab::Indexer &indexer, const TypeEnvironment &env );
+        Cost conversionCost( 
+                const ast::Type * src, const ast::Type * dst, const ast::SymbolTable & symtab, 
+                const ast::TypeEnvironment & env );
 
         // in AlternativeFinder.cc
@@ -127 +133 @@
         // in PolyCost.cc
         int polyCost( Type *type, const TypeEnvironment &env, const SymTab::Indexer &indexer );
+        int polyCost( 
+                const ast::Type * type, const ast::SymbolTable & symtab, const ast::TypeEnvironment & env );
 
         // in SpecCost.cc
         int specCost( Type *type );
+        int specCost( const ast::Type * type );
 
         // in Occurs.cc
@@ -146 +155 @@
         // in AlternativeFinder.cc
         void referenceToRvalueConversion( Expression *& expr, Cost & cost );
+        // in CandidateFinder.cpp
         const ast::Expr * referenceToRvalueConversion( const ast::Expr * expr, Cost & cost );
 

src/SymTab/Mangler.h

@@ -101 +101 @@
         using Mode = bitfield<mangle_flags>;
 
+        static inline Mode typeMode() { return NoOverrideable | Type; }
+
         /// Mangle declaration name
         std::string mangle( const ast::Node * decl, Mode mode = {} );

src/SymTab/Validate.cc

@@ -1367 +1367 @@
                 return addrExpr;
         }
+
+        const ast::Type * validateType( const ast::Type * type, const ast::SymbolTable & symtab ) {
+                #warning unimplemented
+                (void)type; (void)symtab;
+                assert(false);
+                return nullptr;
+        }
 } // namespace SymTab
 

src/SymTab/Validate.h

@@ -22 +22 @@
 class Type;
 
+namespace ast {
+        class Type;
+        class SymbolTable;
+}
+
 namespace SymTab {
         class Indexer;
@@ -28 +33 @@
         void validate( std::list< Declaration * > &translationUnit, bool doDebug = false );
         void validateType( Type *type, const Indexer *indexer );
+
+        const ast::Type * validateType( const ast::Type * type, const ast::SymbolTable & symtab );
 } // namespace SymTab
 

src/Tuples/Tuples.cc

@@ -10 +10 @@
 // Created On       : Mon Jun 17 14:41:00 2019
 // Last Modified By : Andrew Beach
-// Last Modified On : Wed Jun 12 15:43:00 2019
-// Update Count     : 0
+// Last Modified On : Tue Jun 18  9:31:00 2019
+// Update Count     : 1
 //
 
@@ -27 +27 @@
         /// impure.
     struct ImpurityDetector : public ast::WithShortCircuiting {
-                ImpurityDetector( bool ignoreUnique ) : ignoreUnique( ignoreUnique ) {}
                 bool maybeImpure = false;
-                bool ignoreUnique;
 
                 void previsit( ast::ApplicationExpr const * appExpr ) {
-                        visit_children = false;
                         if ( ast::DeclWithType const * function = InitTweak::getFunction( appExpr ) ) {
                                 if ( function->linkage == ast::Linkage::Intrinsic
                                                 && ( function->name == "*?" || function->name == "?[?]" ) ) {
-                                        visit_children = true;
                                         return;
                                 }
                         }
-                        maybeImpure = true;
+                        maybeImpure = true; visit_children = false;
                 }
                 void previsit( ast::UntypedExpr const * ) {
                         maybeImpure = true; visit_children = false;
                 }
+        };
+        struct ImpurityDetectorIgnoreUnique : public ImpurityDetector {
                 void previsit( ast::UniqueExpr const * ) {
-                        if ( ignoreUnique ) {
-                                visit_children = false;
-                        }
+                        visit_children = false;
                 }
         };
 
-        bool detectImpurity( const ast::Expr * expr, bool ignoreUnique ) {
-                ast::Pass<ImpurityDetector> detector( ignoreUnique );
+        template<typename Detector>
+        bool detectImpurity( const ast::Expr * expr ) {
+                ast::Pass<Detector> detector;
                 expr->accept( detector );
                 return detector.pass.maybeImpure;
@@ -59 +56 @@
 } // namespace
 
+bool maybeImpure( const ast::Expr * expr ) {
+        return detectImpurity<ImpurityDetector>( expr );
+}
+
 bool maybeImpureIgnoreUnique( const ast::Expr * expr ) {
-        return detectImpurity( expr, true );
+        return detectImpurity<ImpurityDetectorIgnoreUnique>( expr );
 }
 

src/Tuples/Tuples.h

@@ -10 +10 @@
 // Created On       : Mon May 18 07:44:20 2015
 // Last Modified By : Andrew Beach
-// Last Modified On : Wed Jun 12 10:39:00 2017
-// Update Count     : 17
+// Last Modified On : Tue Jun 18 09:36:00 2019
+// Update Count     : 18
 //
 
@@ -56 +56 @@
         /// returns true if the expression may contain side-effects.
         bool maybeImpure( Expression * expr );
+        bool maybeImpure( const ast::Expr * expr );
 
         /// Returns true if the expression may contain side-effect,