Changeset da7454c for src

Timestamp:

Jun 24, 2019, 2:27:29 PM (5 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:

3623f9d

Parents:

0e464f6 (diff), 67d2b97 (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/Fwd.hpp (modified) (2 diffs)
• AST/TypeSubstitution.hpp (modified) (1 diff)
• ResolvExpr/ConversionCost.cc (modified) (2 diffs)
• ResolvExpr/ConversionCost.h (modified) (3 diffs)
• ResolvExpr/PtrsAssignable.cc (modified) (2 diffs)
• ResolvExpr/typeops.h (modified) (1 diff)
• SymTab/Validate.cc (modified) (5 diffs)

src/AST/Fwd.hpp

@@ -10 +10 @@
 // Created On       : Wed May  8 16:05:00 2019
 // Last Modified By : Andrew Beach
-// Last Modified On : Thr May  9 13:09:00 2019
-// Update Count     : 0
+// Last Modified On : Mon Jun 24 09:48:00 2019
+// Update Count     : 1
 //
 
@@ -129 +129 @@
 class Attribute;
 
+class SymbolTable;
+class TypeEnvironment;
 class TypeSubstitution;
 

src/AST/TypeSubstitution.hpp

@@ -200 +200 @@
 }
 
-/// Instantiate each member of the context given the actual parameters specified, and store the
-/// instantiations for use by the indexer
-template< typename FormalIterator, typename ActualIterator, typename MemberIterator, typename OutputIterator >
-void applySubstitution( FormalIterator formalBegin, FormalIterator formalEnd, ActualIterator actual, MemberIterator memberBegin, MemberIterator memberEnd, OutputIterator out ) {
-        TypeSubstitution sub = TypeSubstitution( formalBegin, formalEnd, actual );
-        for ( auto i = memberBegin; i != memberEnd; ++i ) {
-                sub.apply( *i );
-                *out++ = *i;
-        } // for
-}
-
 } // namespace ast
 

src/ResolvExpr/ConversionCost.cc

@@ -9 +9 @@
 // Author           : Richard C. Bilson
 // Created On       : Sun May 17 07:06:19 2015
-// Last Modified By : Peter A. Buhr
-// Last Modified On : Mon May  6 14:18:22 2019
-// Update Count     : 25
+// Last Modified By : Andrew Beach
+// Last Modified On : Mon Jun 24 13:33:00 2019
+// Update Count     : 26
 //
 
@@ -489 +489 @@
         }
 
-        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);
+static int localPtrsAssignable(const ast::Type * t1, const ast::Type * t2,
+                const ast::SymbolTable &, const ast::TypeEnvironment & env ) {
+        return ptrsAssignable( t1, t2, env );
+}
+
+// TODO: This is used for overload resolution. It might be able to be dropped once the old system
+// is removed.
+static Cost localConversionCost(
+        const ast::Type * src, const ast::Type * dst, const ast::SymbolTable & symtab,
+        const ast::TypeEnvironment & env
+) { return conversionCost( src, dst, symtab, env ); }
+
+Cost conversionCost(
+        const ast::Type * src, const ast::Type * dst, const ast::SymbolTable & symtab,
+        const ast::TypeEnvironment & env
+) {
+        if ( const ast::TypeInstType * inst = dynamic_cast< const ast::TypeInstType * >( dst ) ) {
+                if ( const ast::EqvClass * eqv = env.lookup( inst->name ) ) {
+                        if ( eqv->bound ) {
+                                return conversionCost(src, eqv->bound, symtab, env );
+                        } else {
+                                return Cost::infinity;
+                        }
+                } else if ( const ast::NamedTypeDecl * named = symtab.lookupType( inst->name ) ) {
+                        const ast::TypeDecl * type = dynamic_cast< const ast::TypeDecl * >( named );
+                        assertf( type, "Unexpected typedef." );
+                        if ( type->base ) {
+                                return conversionCost( src, type->base, symtab, env ) + Cost::safe;
+                        }
+                }
+        }
+        if ( typesCompatibleIgnoreQualifiers( src, dst, symtab, env ) ) {
                 return Cost::zero;
-        }
+        } else if ( dynamic_cast< const ast::VoidType * >( dst ) ) {
+                return Cost::safe;
+        } else if ( const ast::ReferenceType * refType =
+                         dynamic_cast< const ast::ReferenceType * >( dst ) ) {
+                return convertToReferenceCost( src, refType, symtab, env, localPtrsAssignable );
+        } else {
+                ast::Pass<ConversionCost_new> converter( dst, symtab, env, localConversionCost );
+                src->accept( converter );
+                return converter.pass.cost;
+        }
+}
+
+Cost convertToReferenceCost( const ast::Type * src, const ast::Type * dst, int diff,
+                const ast::SymbolTable & symtab, const ast::TypeEnvironment & env,
+                NumCostCalculation func ) {
+        if ( 0 < diff ) {
+                Cost cost = convertToReferenceCost(
+                        strict_dynamic_cast< const ast::ReferenceType * >( src )->base,
+                        dst, (diff - 1), symtab, env, func );
+                cost.incReference();
+                return cost;
+        } else if ( diff < -1 ) {
+                Cost cost = convertToReferenceCost(
+                        src, strict_dynamic_cast< const ast::ReferenceType * >( dst )->base,
+                        (diff + 1), symtab, env, func );
+                cost.incReference();
+                return cost;
+        } else if ( 0 == diff ) {
+                const ast::ReferenceType * srcAsRef = dynamic_cast< const ast::ReferenceType * >( src );
+                const ast::ReferenceType * dstAsRef = dynamic_cast< const ast::ReferenceType * >( dst );
+                if ( srcAsRef && dstAsRef ) {
+                        ast::CV::Qualifiers tq1 = srcAsRef->base->qualifiers;
+                        ast::CV::Qualifiers tq2 = dstAsRef->base->qualifiers;
+                        if ( tq1 <= tq2 && typesCompatibleIgnoreQualifiers(
+                                        srcAsRef->base, dstAsRef->base, symtab, env ) ) {
+                                if ( tq1 == tq2 ) {
+                                        return Cost::zero;
+                                } else {
+                                        return Cost::safe;
+                                }
+                        } else {
+                                int assignResult = func( srcAsRef->base, dstAsRef->base, symtab, env );
+                                if ( 0 < assignResult ) {
+                                        return Cost::safe;
+                                } else if ( assignResult < 0 ) {
+                                        return Cost::unsafe;
+                                }
+                        }
+                } else {
+                        ast::Pass<ConversionCost_new> converter( dst, symtab, env, localConversionCost );
+                        src->accept( converter );
+                        return converter.pass.cost;
+                }
+        } else {
+                assert( -1 == diff );
+                const ast::ReferenceType * dstAsRef = dynamic_cast< const ast::ReferenceType * >( dst );
+                assert( dstAsRef );
+                if ( typesCompatibleIgnoreQualifiers( src, dstAsRef->base, symtab, env ) ) {
+                        if ( src->is_lvalue() ) {
+                                if ( src->qualifiers == dstAsRef->base->qualifiers ) {
+                                        return Cost::reference;
+                                } else if ( src->qualifiers < dstAsRef->base->qualifiers ) {
+                                        return Cost::safe;
+                                } else {
+                                        return Cost::unsafe;
+                                }
+                        } else if ( dstAsRef->base->is_const() ) {
+                                return Cost::safe;
+                        } else {
+                                return Cost::unsafe;
+                        }
+                }
+        }
+        return Cost::infinity;
+}
+
+Cost convertToReferenceCost( const ast::Type * src, const ast::ReferenceType * dst,
+            const ast::SymbolTable & symtab, const ast::TypeEnvironment & env,
+                NumCostCalculation func ) {
+        int sdepth = src->referenceDepth(), ddepth = dst->referenceDepth();
+        return convertToReferenceCost( src, dst, sdepth - ddepth, symtab, env, func );
+}
+
+void ConversionCost_new::postvisit( const ast::VoidType * voidType ) {
+        (void)voidType;
+        cost = Cost::infinity;
+}
+
+void ConversionCost_new::postvisit( const ast::BasicType * basicType ) {
+        if ( const ast::BasicType * dstAsBasic = dynamic_cast< const ast::BasicType * >( dst ) ) {
+                int tableResult = costMatrix[ basicType->kind ][ dstAsBasic->kind ];
+                if ( tableResult == -1 ) {
+                        cost = Cost::unsafe;
+                } else {
+                        cost = Cost::zero;
+                        cost.incSafe( tableResult );
+                        cost.incSign( signMatrix[ basicType->kind ][ dstAsBasic->kind ] );
+                }
+        } else if ( dynamic_cast< const ast::EnumInstType * >( dst ) ) {
+                // xxx - not positive this is correct, but appears to allow casting int => enum
+                cost = Cost::unsafe;
+        }
+}
+
+void ConversionCost_new::postvisit( const ast::PointerType * pointerType ) {
+        if ( const ast::PointerType * dstAsPtr = dynamic_cast< const ast::PointerType * >( dst ) ) {
+                ast::CV::Qualifiers tq1 = pointerType->base->qualifiers;
+                ast::CV::Qualifiers tq2 = dstAsPtr->base->qualifiers;
+                if ( tq1 <= tq2 && typesCompatibleIgnoreQualifiers(
+                                pointerType->base, dstAsPtr->base, symtab, env ) ) {
+                        if ( tq1 == tq2 ) {
+                                cost = Cost::zero;
+                        } else {
+                                cost = Cost::safe;
+                        }
+                } else {
+                        int assignResult = ptrsAssignable( pointerType->base, dstAsPtr->base, env );
+                        if ( 0 < assignResult && tq1 <= tq2 ) {
+                                if ( tq1 == tq2 ) {
+                                        cost = Cost::safe;
+                                } else {
+                                        cost = Cost::safe + Cost::safe;
+                                }
+                        } else if ( assignResult < 0 ) {
+                                cost = Cost::unsafe;
+                        } // else Cost::infinity
+                }
+        }
+}
+
+void ConversionCost_new::postvisit( const ast::ArrayType * arrayType ) {
+        (void)arrayType;
+}
+
+void ConversionCost_new::postvisit( const ast::ReferenceType * refType ) {
+        assert( nullptr == dynamic_cast< const ast::ReferenceType * >( dst ) );
+
+        cost = costCalc( refType->base, dst, symtab, env );
+        if ( refType->base->qualifiers == dst->qualifiers ) {
+                cost.incReference();
+        } else if ( refType->base->qualifiers < dst->qualifiers ) {
+                cost.incSafe();
+        } else {
+                cost.incUnsafe();
+        }
+}
+
+void ConversionCost_new::postvisit( const ast::FunctionType * functionType ) {
+        (void)functionType;
+}
+
+void ConversionCost_new::postvisit( const ast::StructInstType * structInstType ) {
+        if ( const ast::StructInstType * dstAsInst =
+                        dynamic_cast< const ast::StructInstType * >( dst ) ) {
+                if ( structInstType->name == dstAsInst->name ) {
+                        cost = Cost::zero;
+                }
+        }
+}
+
+void ConversionCost_new::postvisit( const ast::UnionInstType * unionInstType ) {
+        if ( const ast::UnionInstType * dstAsInst =
+                        dynamic_cast< const ast::UnionInstType * >( dst ) ) {
+                if ( unionInstType->name == dstAsInst->name ) {
+                        cost = Cost::zero;
+                }
+        }
+}
+
+void ConversionCost_new::postvisit( const ast::EnumInstType * enumInstType ) {
+        (void)enumInstType;
+        static const ast::BasicType integer( ast::BasicType::SignedInt );
+        cost = costCalc( &integer, dst, symtab, env );
+        if ( cost < Cost::unsafe ) {
+                cost.incSafe();
+        }
+}
+
+void ConversionCost_new::postvisit( const ast::TraitInstType * traitInstType ) {
+        (void)traitInstType;
+}
+
+void ConversionCost_new::postvisit( const ast::TypeInstType * typeInstType ) {
+        if ( const ast::EqvClass * eqv = env.lookup( typeInstType->name ) ) {
+                cost = costCalc( eqv->bound, dst, symtab, env );
+        } else if ( const ast::TypeInstType * dstAsInst =
+                        dynamic_cast< const ast::TypeInstType * >( dst ) ) {
+                if ( typeInstType->name == dstAsInst->name ) {
+                        cost = Cost::zero;
+                }
+        } else if ( const ast::NamedTypeDecl * namedType = symtab.lookupType( typeInstType->name ) ) {
+                const ast::TypeDecl * type = dynamic_cast< const ast::TypeDecl * >( namedType );
+                assertf( type, "Unexpected typedef.");
+                if ( type->base ) {
+                        cost = costCalc( type->base, dst, symtab, env ) + Cost::safe;
+                }
+        }
+}
+
+void ConversionCost_new::postvisit( const ast::TupleType * tupleType ) {
+        Cost c = Cost::zero;
+        if ( const ast::TupleType * dstAsTuple = dynamic_cast< const ast::TupleType * >( dst ) ) {
+                auto srcIt = tupleType->types.begin();
+                auto dstIt = dstAsTuple->types.begin();
+                auto srcEnd = tupleType->types.end();
+                auto dstEnd = dstAsTuple->types.end();
+                while ( srcIt != srcEnd && dstIt != dstEnd ) {
+                        Cost newCost = costCalc( *srcIt++, *dstIt++, symtab, env );
+                        if ( newCost == Cost::infinity ) {
+                                return;
+                        }
+                        c += newCost;
+                }
+                if ( dstIt != dstEnd ) {
+                        cost = Cost::infinity;
+                } else {
+                        cost = c;
+                }
+        }
+}
+
+void ConversionCost_new::postvisit( const ast::VarArgsType * varArgsType ) {
+        (void)varArgsType;
+        if ( dynamic_cast< const ast::VarArgsType * >( dst ) ) {
+                cost = Cost::zero;
+        }
+}
+
+void ConversionCost_new::postvisit( const ast::ZeroType * zeroType ) {
+        (void)zeroType;
+        if ( dynamic_cast< const ast::ZeroType * >( dst ) ) {
+                cost = Cost::zero;
+        } else if ( const ast::BasicType * dstAsBasic =
+                        dynamic_cast< const ast::BasicType * >( dst ) ) {
+                int tableResult = costMatrix[ ast::BasicType::SignedInt ][ dstAsBasic->kind ];
+                if ( -1 == tableResult ) {
+                        cost = Cost::unsafe;
+                } else {
+                        cost = Cost::zero;
+                        cost.incSafe( tableResult + 1 );
+                        cost.incSign( signMatrix[ ast::BasicType::SignedInt ][ dstAsBasic->kind ] );
+                }
+        }
+}
+
+void ConversionCost_new::postvisit( const ast::OneType * oneType ) {
+        (void)oneType;
+        if ( dynamic_cast< const ast::OneType * >( dst ) ) {
+                cost = Cost::zero;
+        } else if ( const ast::BasicType * dstAsBasic =
+                        dynamic_cast< const ast::BasicType * >( dst ) ) {
+                int tableResult = costMatrix[ ast::BasicType::SignedInt ][ dstAsBasic->kind ];
+                if ( -1 == tableResult ) {
+                        cost = Cost::unsafe;
+                } else {
+                        cost = Cost::zero;
+                        cost.incSafe( tableResult + 1 );
+                        cost.incSign( signMatrix[ ast::BasicType::SignedInt ][ dstAsBasic->kind ] );
+                }
+        } else if ( dynamic_cast< const ast::PointerType * >( dst ) ) {
+                cost = Cost::zero;
+                cost.incSafe( maxIntCost + 2 );
+        }
+}
+
+
 } // namespace ResolvExpr
 

src/ResolvExpr/ConversionCost.h

@@ -9 +9 @@
 // Author           : Richard C. Bilson
 // Created On       : Sun May 17 09:37:28 2015
-// Last Modified By : Peter A. Buhr
-// Last Modified On : Sat Jul 22 09:38:24 2017
-// Update Count     : 4
+// Last Modified By : Andrew Beach
+// Last Modified On : Mon Jun 24 10:00:00 2019
+// Update Count     : 5
 //
 
@@ -20 +20 @@
 #include "Cost.h"             // for Cost
 
+#include "AST/Fwd.hpp"
+#include "AST/Pass.hpp"       // for WithShortCircuiting
 #include "Common/PassVisitor.h"
 #include "SynTree/Visitor.h"  // for Visitor
@@ -65 +67 @@
         typedef std::function<int(Type *, Type *, const SymTab::Indexer &, const TypeEnvironment &)> PtrsFunction;
         Cost convertToReferenceCost( Type * src, ReferenceType * dest, const SymTab::Indexer & indexer, const TypeEnvironment & env, PtrsFunction func );
+
+// Some function pointer types, differ in return type.
+using CostCalculation = std::function<Cost(const ast::Type *, const ast::Type *,
+        const ast::SymbolTable &, const ast::TypeEnvironment &)>;
+using NumCostCalculation = std::function<int(const ast::Type *, const ast::Type *,
+        const ast::SymbolTable &, const ast::TypeEnvironment &)>;
+
+// TODO: When the old ConversionCost is removed, get ride of the _new suffix.
+class ConversionCost_new : public ast::WithShortCircuiting {
+        const ast::Type * dst;
+        const ast::SymbolTable & symtab;
+        const ast::TypeEnvironment & env;
+        CostCalculation costCalc;
+public:
+        Cost cost;
+
+        ConversionCost_new( const ast::Type * dst, const ast::SymbolTable & symtab,
+                        const ast::TypeEnvironment & env, CostCalculation costCalc ) :
+                dst( dst ), symtab( symtab ), env( env ), costCalc( costCalc ), cost( Cost::infinity )
+        {}
+
+        void previsit( const ast::Node * ) { visit_children = false; }
+
+        void postvisit( const ast::VoidType * voidType );
+        void postvisit( const ast::BasicType * basicType );
+        void postvisit( const ast::PointerType * pointerType );
+        void postvisit( const ast::ArrayType * arrayType );
+        void postvisit( const ast::ReferenceType * refType );
+        void postvisit( const ast::FunctionType * functionType );
+        void postvisit( const ast::StructInstType * structInstType );
+        void postvisit( const ast::UnionInstType * unionInstType );
+        void postvisit( const ast::EnumInstType * enumInstType );
+        void postvisit( const ast::TraitInstType * traitInstType );
+        void postvisit( const ast::TypeInstType * typeInstType );
+        void postvisit( const ast::TupleType * tupleType );
+        void postvisit( const ast::VarArgsType * varArgsType );
+        void postvisit( const ast::ZeroType * zeroType );
+        void postvisit( const ast::OneType * oneType );
+};
+
+Cost convertToReferenceCost( const ast::Type * src, const ast::ReferenceType * dest,
+        const ast::SymbolTable & indexer, const ast::TypeEnvironment & env, NumCostCalculation func );
+
 } // namespace ResolvExpr
 

src/ResolvExpr/PtrsAssignable.cc

@@ -14 +14 @@
 //
 
+#include "AST/Fwd.hpp"
 #include "Common/PassVisitor.h"
 #include "ResolvExpr/TypeEnvironment.h"  // for EqvClass, TypeEnvironment
@@ -107 +108 @@
         void PtrsAssignable::postvisit(  __attribute__((unused)) OneType *oneType ) {}
 
+int ptrsAssignable( const ast::Type * src, const ast::Type * dst,
+                const ast::TypeEnvironment & env ) {
+        #warning unimplemented
+        (void)src;
+        (void)dst;
+        (void)env;
+        assert(0);
+        return 0;
+}
+
 } // namespace ResolvExpr
 

src/ResolvExpr/typeops.h

@@ -94 +94 @@
         // in PtrsAssignable.cc
         int ptrsAssignable( Type *src, Type *dest, const TypeEnvironment &env );
+        int ptrsAssignable( const ast::Type * src, const ast::Type * dst,
+                const ast::TypeEnvironment & env );
 
         // in PtrsCastable.cc

src/SymTab/Validate.cc

@@ -53 +53 @@
 #include "AST/SymbolTable.hpp"
 #include "AST/Type.hpp"
+#include "AST/TypeSubstitution.hpp"
 #include "CodeGen/CodeGenerator.h"     // for genName
 #include "CodeGen/OperatorTable.h"     // for isCtorDtor, isCtorDtorAssign
@@ -1430 +1431 @@
         };
 
+        /// expand assertions from a trait instance, performing appropriate type variable substitutions
+        void expandAssertions( 
+                const ast::TraitInstType * inst, std::vector< ast::ptr< ast::DeclWithType > > & out 
+        ) {
+                assertf( inst->base, "Trait instance not linked to base trait: %s", toCString( inst ) );
+
+                // build list of trait members, substituting trait decl parameters for instance parameters
+                ast::TypeSubstitution sub{ 
+                        inst->base->params.begin(), inst->base->params.end(), inst->params.begin() };
+                // deliberately take ast::ptr by-value to ensure this does not mutate inst->base
+                for ( ast::ptr< ast::Decl > decl : inst->base->members ) {
+                        auto member = decl.strict_as< ast::DeclWithType >();
+                        sub.apply( member );
+                        out.emplace_back( member );
+                }
+        }
+
         /// Associates forward declarations of aggregates with their definitions
         class LinkReferenceToTypes_new final 
@@ -1690 +1708 @@
                 const ast::Decl * postvisit( const ast::TraitDecl * traitDecl ) {
                         // set the "sized" status for the special "sized" trait
-                        if ( traitDecl->name != "sized" ) return traitDecl;
-
-                        assertf( traitDecl->params.size() == 1, "Built-in trait 'sized' has incorrect number "
-                                "of parameters: %zd", traitDecl->params.size() );
-
-                        return ast::mutate_field_index( 
-                                traitDecl, &ast::TraitDecl::params, 0, 
-                                ast::mutate_field( 
-                                        traitDecl->params.front().get(), &ast::TypeDecl::sized, true ) );
+                        if ( traitDecl->name == "sized" ) {
+                                assertf( traitDecl->params.size() == 1, "Built-in trait 'sized' has incorrect "
+                                        "number of parameters: %zd", traitDecl->params.size() );
+
+                                traitDecl = ast::mutate_field_index( 
+                                        traitDecl, &ast::TraitDecl::params, 0, 
+                                        ast::mutate_field( 
+                                                traitDecl->params.front().get(), &ast::TypeDecl::sized, true ) );
+                        }
+
+                        // move assertions from type parameters into the body of the trait
+                        std::vector< ast::ptr< ast::DeclWithType > > added;
+                        for ( const ast::TypeDecl * td : traitDecl->params ) {
+                                for ( const ast::DeclWithType * assn : td->assertions ) {
+                                        auto inst = dynamic_cast< const ast::TraitInstType * >( assn->get_type() );
+                                        if ( inst ) {
+                                                expandAssertions( inst, added );
+                                        } else {
+                                                added.emplace_back( assn );
+                                        }
+                                }
+                        }
+                        if ( ! added.empty() ) {
+                                auto mut = mutate( traitDecl );
+                                for ( const ast::DeclWithType * decl : added ) {
+                                        mut->members.emplace_back( decl );
+                                }
+                                traitDecl = mut;
+                        }
+                        
+                        return traitDecl;
                 }
         };
@@ -1704 +1744 @@
         /// Replaces array and function types in forall lists by appropriate pointer type and assigns 
         /// each object and function declaration a unique ID
-        struct ForallPointerDecay_new {
-                #warning incomplete
+        class ForallPointerDecay_new {
+                const CodeLocation & location;
+        public:
+                ForallPointerDecay_new( const CodeLocation & loc ) : location( loc ) {}
+
+                const ast::ObjectDecl * previsit( const ast::ObjectDecl * obj ) {
+                        // ensure that operator names only apply to functions or function pointers
+                        if ( 
+                                CodeGen::isOperator( obj->name ) 
+                                && ! dynamic_cast< const ast::FunctionType * >( obj->type->stripDeclarator() )
+                        ) {
+                                SemanticError( obj->location, toCString( "operator ", obj->name.c_str(), " is not "
+                                        "a function or function pointer." )  );
+                        }
+
+                        // ensure object has unique ID
+                        if ( obj->uniqueId ) return obj;
+                        auto mut = mutate( obj );
+                        mut->fixUniqueId();
+                        return mut;
+                }
+
+                const ast::FunctionDecl * previsit( const ast::FunctionDecl * func ) {
+                        // ensure function has unique ID
+                        if ( func->uniqueId ) return func;
+                        auto mut = mutate( func );
+                        mut->fixUniqueId();
+                        return mut;
+                }
+
+                /// Fix up assertions -- flattens assertion lists, removing all trait instances
+                template< typename node_t, typename parent_t >
+                static const node_t * forallFixer( 
+                        const CodeLocation & loc, const node_t * node, 
+                        ast::ParameterizedType::ForallList parent_t::* forallField
+                ) {
+                        for ( unsigned i = 0; i < (node->*forallField).size(); ++i ) {
+                                const ast::TypeDecl * type = (node->*forallField)[i];
+                                if ( type->assertions.empty() ) continue;
+
+                                std::vector< ast::ptr< ast::DeclWithType > > asserts;
+                                asserts.reserve( type->assertions.size() );
+
+                                // expand trait instances into their members
+                                for ( const ast::DeclWithType * assn : type->assertions ) {
+                                        auto traitInst = 
+                                                dynamic_cast< const ast::TraitInstType * >( assn->get_type() ); 
+                                        if ( traitInst ) {
+                                                // expand trait instance to all its members
+                                                expandAssertions( traitInst, asserts );
+                                        } else {
+                                                // pass other assertions through
+                                                asserts.emplace_back( assn );
+                                        }
+                                }
+
+                                // apply FixFunction to every assertion to check for invalid void type
+                                for ( ast::ptr< ast::DeclWithType > & assn : asserts ) {
+                                        bool isVoid = false;
+                                        assn = fixFunction( assn, isVoid );
+                                        if ( isVoid ) {
+                                                SemanticError( loc, node, "invalid type void in assertion of function " );
+                                        }
+                                }
+
+                                // place mutated assertion list in node
+                                auto mut = mutate( type );
+                                mut->assertions = move( asserts );
+                                node = ast::mutate_field_index( node, forallField, i, mut );
+                        }
+                        return node;
+                }
+
+                const ast::FunctionType * previsit( const ast::FunctionType * ftype ) {
+                        return forallFixer( location, ftype, &ast::FunctionType::forall );
+                }
+
+                const ast::StructDecl * previsit( const ast::StructDecl * aggrDecl ) {
+                        return forallFixer( aggrDecl->location, aggrDecl, &ast::StructDecl::params );
+                }
+
+                const ast::UnionDecl * previsit( const ast::UnionDecl * aggrDecl ) {
+                        return forallFixer( aggrDecl->location, aggrDecl, &ast::UnionDecl::params );
+                }
         };
 } // anonymous namespace
@@ -1713 +1835 @@
         ast::Pass< EnumAndPointerDecay_new > epc;
         ast::Pass< LinkReferenceToTypes_new > lrt{ loc, symtab };
-        ast::Pass< ForallPointerDecay_new > fpd;
+        ast::Pass< ForallPointerDecay_new > fpd{ loc };
 
         return type->accept( epc )->accept( lrt )->accept( fpd );