Changes in src/ResolvExpr/CandidateFinder.cpp [432ce7a:b69233ac]

File:

• src/ResolvExpr/CandidateFinder.cpp (modified) (21 diffs)

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(