source: src/SymTab/Validate.cc @ a9a259c

//
// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// Validate.cc --
//
// Author           : Richard C. Bilson
// Created On       : Sun May 17 21:50:04 2015
// Last Modified By : Rob Schluntz
// Last Modified On : Mon Feb 22 12:26:37 2016
// Update Count     : 297
//

// The "validate" phase of translation is used to take a syntax tree and convert it into a standard form that aims to be
// as regular in structure as possible.  Some assumptions can be made regarding the state of the tree after this pass is
// complete, including:
//
// - No nested structure or union definitions; any in the input are "hoisted" to the level of the containing struct or
//   union.
//
// - All enumeration constants have type EnumInstType.
//
// - The type "void" never occurs in lists of function parameter or return types; neither do tuple types.  A function
//   taking no arguments has no argument types, and tuples are flattened.
//
// - No context instances exist; they are all replaced by the set of declarations signified by the context, instantiated
//   by the particular set of type arguments.
//
// - Every declaration is assigned a unique id.
//
// - No typedef declarations or instances exist; the actual type is substituted for each instance.
//
// - Each type, struct, and union definition is followed by an appropriate assignment operator.
//
// - Each use of a struct or union is connected to a complete definition of that struct or union, even if that
//   definition occurs later in the input.

#include <list>
#include <iterator>
#include "Validate.h"
#include "SynTree/Visitor.h"
#include "SynTree/Mutator.h"
#include "SynTree/Type.h"
#include "SynTree/Statement.h"
#include "SynTree/TypeSubstitution.h"
#include "Indexer.h"
#include "FixFunction.h"
// #include "ImplementationType.h"
#include "Common/utility.h"
#include "Common/UniqueName.h"
#include "AddVisit.h"
#include "MakeLibCfa.h"
#include "TypeEquality.h"
#include "ResolvExpr/typeops.h"

#define debugPrint( x ) if ( doDebug ) { std::cout << x; }

namespace SymTab {
        class HoistStruct : public Visitor {
          public:
                /// Flattens nested struct types
                static void hoistStruct( std::list< Declaration * > &translationUnit );

                std::list< Declaration * > &get_declsToAdd() { return declsToAdd; }

                virtual void visit( StructDecl *aggregateDecl );
                virtual void visit( UnionDecl *aggregateDecl );

                virtual void visit( CompoundStmt *compoundStmt );
                virtual void visit( IfStmt *ifStmt );
                virtual void visit( WhileStmt *whileStmt );
                virtual void visit( ForStmt *forStmt );
                virtual void visit( SwitchStmt *switchStmt );
                virtual void visit( ChooseStmt *chooseStmt );
                virtual void visit( CaseStmt *caseStmt );
                virtual void visit( CatchStmt *catchStmt );
          private:
                HoistStruct();

                template< typename AggDecl > void handleAggregate( AggDecl *aggregateDecl );

                std::list< Declaration * > declsToAdd;
                bool inStruct;
        };

        /// Replaces enum types by int, and function or array types in function parameter and return lists by appropriate pointers.
        class Pass1 : public Visitor {
                typedef Visitor Parent;
                virtual void visit( EnumDecl *aggregateDecl );
                virtual void visit( FunctionType *func );
        };

        /// Associates forward declarations of aggregates with their definitions
        class Pass2 : public Indexer {
                typedef Indexer Parent;
          public:
                Pass2( bool doDebug, const Indexer *indexer );
          private:
                virtual void visit( StructInstType *structInst );
                virtual void visit( UnionInstType *unionInst );
                virtual void visit( ContextInstType *contextInst );
                virtual void visit( StructDecl *structDecl );
                virtual void visit( UnionDecl *unionDecl );
                virtual void visit( TypeInstType *typeInst );

                const Indexer *indexer;

                typedef std::map< std::string, std::list< StructInstType * > > ForwardStructsType;
                typedef std::map< std::string, std::list< UnionInstType * > > ForwardUnionsType;
                ForwardStructsType forwardStructs;
                ForwardUnionsType forwardUnions;
        };

        /// Replaces array and function types in forall lists by appropriate pointer type
        class Pass3 : public Indexer {
                typedef Indexer Parent;
          public:
                Pass3( const Indexer *indexer );
          private:
                virtual void visit( ObjectDecl *object );
                virtual void visit( FunctionDecl *func );

                const Indexer *indexer;
        };

        class AutogenerateRoutines : public Visitor {
          public:
                /// Generates assignment operators for aggregate types as required
                static void autogenerateRoutines( std::list< Declaration * > &translationUnit );

                std::list< Declaration * > &get_declsToAdd() { return declsToAdd; }

                virtual void visit( EnumDecl *enumDecl );
                virtual void visit( StructDecl *structDecl );
                virtual void visit( UnionDecl *structDecl );
                virtual void visit( TypeDecl *typeDecl );
                virtual void visit( ContextDecl *ctxDecl );
                virtual void visit( FunctionDecl *functionDecl );

                virtual void visit( FunctionType *ftype );
                virtual void visit( PointerType *ftype );

                virtual void visit( CompoundStmt *compoundStmt );
                virtual void visit( IfStmt *ifStmt );
                virtual void visit( WhileStmt *whileStmt );
                virtual void visit( ForStmt *forStmt );
                virtual void visit( SwitchStmt *switchStmt );
                virtual void visit( ChooseStmt *chooseStmt );
                virtual void visit( CaseStmt *caseStmt );
                virtual void visit( CatchStmt *catchStmt );

                AutogenerateRoutines() : functionNesting( 0 ) {}
          private:
                template< typename StmtClass > void visitStatement( StmtClass *stmt );

                std::list< Declaration * > declsToAdd;
                std::set< std::string > structsDone;
                unsigned int functionNesting;                   // current level of nested functions
        };

        class ReturnChecker : public Visitor {
          public:
                /// Checks that return statements return nothing if their return type is void
                /// and return something if the return type is non-void.
                static void checkFunctionReturns( std::list< Declaration * > & translationUnit );

          private:
                virtual void visit( FunctionDecl * functionDecl );

                virtual void visit( ReturnStmt * returnStmt );

                std::list< DeclarationWithType * > returnVals;
        };

        class EliminateTypedef : public Mutator {
          public:
                EliminateTypedef() : scopeLevel( 0 ) {}
                /// Replaces typedefs by forward declarations
                static void eliminateTypedef( std::list< Declaration * > &translationUnit );
          private:
                virtual Declaration *mutate( TypedefDecl *typeDecl );
                virtual TypeDecl *mutate( TypeDecl *typeDecl );
                virtual DeclarationWithType *mutate( FunctionDecl *funcDecl );
                virtual DeclarationWithType *mutate( ObjectDecl *objDecl );
                virtual CompoundStmt *mutate( CompoundStmt *compoundStmt );
                virtual Type *mutate( TypeInstType *aggregateUseType );
                virtual Expression *mutate( CastExpr *castExpr );

                virtual Declaration *mutate( StructDecl * structDecl );
                virtual Declaration *mutate( UnionDecl * unionDecl );
                virtual Declaration *mutate( EnumDecl * enumDecl );
                virtual Declaration *mutate( ContextDecl * contextDecl );

                template<typename AggDecl>
                AggDecl *handleAggregate( AggDecl * aggDecl );

                typedef std::map< std::string, std::pair< TypedefDecl *, int > > TypedefMap;
                TypedefMap typedefNames;
                int scopeLevel;
        };

        class VerifyCtorDtor : public Visitor {
        public:
                /// ensure that constructors and destructors have at least one
                /// parameter, the first of which must be a pointer, and no
                /// return values.
                static void verify( std::list< Declaration * > &translationUnit );

                // VerifyCtorDtor() {}

                virtual void visit( FunctionDecl *funcDecl );
        private:
        };

        void validate( std::list< Declaration * > &translationUnit, bool doDebug ) {
                Pass1 pass1;
                Pass2 pass2( doDebug, 0 );
                Pass3 pass3( 0 );
                EliminateTypedef::eliminateTypedef( translationUnit );
                HoistStruct::hoistStruct( translationUnit );
                acceptAll( translationUnit, pass1 );
                acceptAll( translationUnit, pass2 );
                ReturnChecker::checkFunctionReturns( translationUnit );
                AutogenerateRoutines::autogenerateRoutines( translationUnit );
                acceptAll( translationUnit, pass3 );
                VerifyCtorDtor::verify( translationUnit );
        }

        void validateType( Type *type, const Indexer *indexer ) {
                Pass1 pass1;
                Pass2 pass2( false, indexer );
                Pass3 pass3( indexer );
                type->accept( pass1 );
                type->accept( pass2 );
                type->accept( pass3 );
        }

        template< typename Visitor >
        void acceptAndAdd( std::list< Declaration * > &translationUnit, Visitor &visitor, bool addBefore ) {
                std::list< Declaration * >::iterator i = translationUnit.begin();
                while ( i != translationUnit.end() ) {
                        (*i)->accept( visitor );
                        std::list< Declaration * >::iterator next = i;
                        next++;
                        if ( ! visitor.get_declsToAdd().empty() ) {
                                translationUnit.splice( addBefore ? i : next, visitor.get_declsToAdd() );
                        } // if
                        i = next;
                } // while
        }

        void HoistStruct::hoistStruct( std::list< Declaration * > &translationUnit ) {
                HoistStruct hoister;
                acceptAndAdd( translationUnit, hoister, true );
        }

        HoistStruct::HoistStruct() : inStruct( false ) {
        }

        void filter( std::list< Declaration * > &declList, bool (*pred)( Declaration * ), bool doDelete ) {
                std::list< Declaration * >::iterator i = declList.begin();
                while ( i != declList.end() ) {
                        std::list< Declaration * >::iterator next = i;
                        ++next;
                        if ( pred( *i ) ) {
                                if ( doDelete ) {
                                        delete *i;
                                } // if
                                declList.erase( i );
                        } // if
                        i = next;
                } // while
        }

        bool isStructOrUnion( Declaration *decl ) {
                return dynamic_cast< StructDecl * >( decl ) || dynamic_cast< UnionDecl * >( decl );
        }

        template< typename AggDecl >
        void HoistStruct::handleAggregate( AggDecl *aggregateDecl ) {
                if ( inStruct ) {
                        // Add elements in stack order corresponding to nesting structure.
                        declsToAdd.push_front( aggregateDecl );
                        Visitor::visit( aggregateDecl );
                } else {
                        inStruct = true;
                        Visitor::visit( aggregateDecl );
                        inStruct = false;
                } // if
                // Always remove the hoisted aggregate from the inner structure.
                filter( aggregateDecl->get_members(), isStructOrUnion, false );
        }

        void HoistStruct::visit( StructDecl *aggregateDecl ) {
                handleAggregate( aggregateDecl );
        }

        void HoistStruct::visit( UnionDecl *aggregateDecl ) {
                handleAggregate( aggregateDecl );
        }

        void HoistStruct::visit( CompoundStmt *compoundStmt ) {
                addVisit( compoundStmt, *this );
        }

        void HoistStruct::visit( IfStmt *ifStmt ) {
                addVisit( ifStmt, *this );
        }

        void HoistStruct::visit( WhileStmt *whileStmt ) {
                addVisit( whileStmt, *this );
        }

        void HoistStruct::visit( ForStmt *forStmt ) {
                addVisit( forStmt, *this );
        }

        void HoistStruct::visit( SwitchStmt *switchStmt ) {
                addVisit( switchStmt, *this );
        }

        void HoistStruct::visit( ChooseStmt *switchStmt ) {
                addVisit( switchStmt, *this );
        }

        void HoistStruct::visit( CaseStmt *caseStmt ) {
                addVisit( caseStmt, *this );
        }

        void HoistStruct::visit( CatchStmt *cathStmt ) {
                addVisit( cathStmt, *this );
        }

        void Pass1::visit( EnumDecl *enumDecl ) {
                // Set the type of each member of the enumeration to be EnumConstant

                for ( std::list< Declaration * >::iterator i = enumDecl->get_members().begin(); i != enumDecl->get_members().end(); ++i ) {
                        ObjectDecl * obj = dynamic_cast< ObjectDecl * >( *i );
                        assert( obj );
                        // obj->set_type( new EnumInstType( Type::Qualifiers( true, false, false, false, false, false ), enumDecl->get_name() ) );
                        BasicType * enumType = new BasicType( Type::Qualifiers(), BasicType::SignedInt );
                        obj->set_type( enumType ) ;
                } // for
                Parent::visit( enumDecl );
        }

        namespace {
                template< typename DWTIterator >
                void fixFunctionList( DWTIterator begin, DWTIterator end, FunctionType *func ) {
                        // the only case in which "void" is valid is where it is the only one in the list; then it should be removed
                        // entirely other fix ups are handled by the FixFunction class
                        if ( begin == end ) return;
                        FixFunction fixer;
                        DWTIterator i = begin;
                        *i = (*i )->acceptMutator( fixer );
                        if ( fixer.get_isVoid() ) {
                                DWTIterator j = i;
                                ++i;
                                func->get_parameters().erase( j );
                                if ( i != end ) {
                                        throw SemanticError( "invalid type void in function type ", func );
                                } // if
                        } else {
                                ++i;
                                for ( ; i != end; ++i ) {
                                        FixFunction fixer;
                                        *i = (*i )->acceptMutator( fixer );
                                        if ( fixer.get_isVoid() ) {
                                                throw SemanticError( "invalid type void in function type ", func );
                                        } // if
                                } // for
                        } // if
                }
        }

        void Pass1::visit( FunctionType *func ) {
                // Fix up parameters and return types
                fixFunctionList( func->get_parameters().begin(), func->get_parameters().end(), func );
                fixFunctionList( func->get_returnVals().begin(), func->get_returnVals().end(), func );
                Visitor::visit( func );
        }

        Pass2::Pass2( bool doDebug, const Indexer *other_indexer ) : Indexer( doDebug ) {
                if ( other_indexer ) {
                        indexer = other_indexer;
                } else {
                        indexer = this;
                } // if
        }

        void Pass2::visit( StructInstType *structInst ) {
                Parent::visit( structInst );
                StructDecl *st = indexer->lookupStruct( structInst->get_name() );
                // it's not a semantic error if the struct is not found, just an implicit forward declaration
                if ( st ) {
                        //assert( ! structInst->get_baseStruct() || structInst->get_baseStruct()->get_members().empty() || ! st->get_members().empty() );
                        structInst->set_baseStruct( st );
                } // if
                if ( ! st || st->get_members().empty() ) {
                        // use of forward declaration
                        forwardStructs[ structInst->get_name() ].push_back( structInst );
                } // if
        }

        void Pass2::visit( UnionInstType *unionInst ) {
                Parent::visit( unionInst );
                UnionDecl *un = indexer->lookupUnion( unionInst->get_name() );
                // it's not a semantic error if the union is not found, just an implicit forward declaration
                if ( un ) {
                        unionInst->set_baseUnion( un );
                } // if
                if ( ! un || un->get_members().empty() ) {
                        // use of forward declaration
                        forwardUnions[ unionInst->get_name() ].push_back( unionInst );
                } // if
        }

        void Pass2::visit( ContextInstType *contextInst ) {
                Parent::visit( contextInst );
                ContextDecl *ctx = indexer->lookupContext( contextInst->get_name() );
                if ( ! ctx ) {
                        throw SemanticError( "use of undeclared context " + contextInst->get_name() );
                } // if
                for ( std::list< TypeDecl * >::const_iterator i = ctx->get_parameters().begin(); i != ctx->get_parameters().end(); ++i ) {
                        for ( std::list< DeclarationWithType * >::const_iterator assert = (*i )->get_assertions().begin(); assert != (*i )->get_assertions().end(); ++assert ) {
                                if ( ContextInstType *otherCtx = dynamic_cast< ContextInstType * >(*assert ) ) {
                                        cloneAll( otherCtx->get_members(), contextInst->get_members() );
                                } else {
                                        contextInst->get_members().push_back( (*assert )->clone() );
                                } // if
                        } // for
                } // for

                if ( ctx->get_parameters().size() != contextInst->get_parameters().size() ) {
                        throw SemanticError( "incorrect number of context parameters: ", contextInst );
                } // if

                applySubstitution( ctx->get_parameters().begin(), ctx->get_parameters().end(), contextInst->get_parameters().begin(), ctx->get_members().begin(), ctx->get_members().end(), back_inserter( contextInst->get_members() ) );
        }

        void Pass2::visit( StructDecl *structDecl ) {
                if ( ! structDecl->get_members().empty() ) {
                        ForwardStructsType::iterator fwds = forwardStructs.find( structDecl->get_name() );
                        if ( fwds != forwardStructs.end() ) {
                                for ( std::list< StructInstType * >::iterator inst = fwds->second.begin(); inst != fwds->second.end(); ++inst ) {
                                        (*inst )->set_baseStruct( structDecl );
                                } // for
                                forwardStructs.erase( fwds );
                        } // if
                } // if
                Indexer::visit( structDecl );
        }

        void Pass2::visit( UnionDecl *unionDecl ) {
                if ( ! unionDecl->get_members().empty() ) {
                        ForwardUnionsType::iterator fwds = forwardUnions.find( unionDecl->get_name() );
                        if ( fwds != forwardUnions.end() ) {
                                for ( std::list< UnionInstType * >::iterator inst = fwds->second.begin(); inst != fwds->second.end(); ++inst ) {
                                        (*inst )->set_baseUnion( unionDecl );
                                } // for
                                forwardUnions.erase( fwds );
                        } // if
                } // if
                Indexer::visit( unionDecl );
        }

        void Pass2::visit( TypeInstType *typeInst ) {
                if ( NamedTypeDecl *namedTypeDecl = lookupType( typeInst->get_name() ) ) {
                        if ( TypeDecl *typeDecl = dynamic_cast< TypeDecl * >( namedTypeDecl ) ) {
                                typeInst->set_isFtype( typeDecl->get_kind() == TypeDecl::Ftype );
                        } // if
                } // if
        }

        Pass3::Pass3( const Indexer *other_indexer ) :  Indexer( false ) {
                if ( other_indexer ) {
                        indexer = other_indexer;
                } else {
                        indexer = this;
                } // if
        }

        /// Fix up assertions
        void forallFixer( Type *func ) {
                for ( std::list< TypeDecl * >::iterator type = func->get_forall().begin(); type != func->get_forall().end(); ++type ) {
                        std::list< DeclarationWithType * > toBeDone, nextRound;
                        toBeDone.splice( toBeDone.end(), (*type )->get_assertions() );
                        while ( ! toBeDone.empty() ) {
                                for ( std::list< DeclarationWithType * >::iterator assertion = toBeDone.begin(); assertion != toBeDone.end(); ++assertion ) {
                                        if ( ContextInstType *ctx = dynamic_cast< ContextInstType * >( (*assertion )->get_type() ) ) {
                                                for ( std::list< Declaration * >::const_iterator i = ctx->get_members().begin(); i != ctx->get_members().end(); ++i ) {
                                                        DeclarationWithType *dwt = dynamic_cast< DeclarationWithType * >( *i );
                                                        assert( dwt );
                                                        nextRound.push_back( dwt->clone() );
                                                }
                                                delete ctx;
                                        } else {
                                                FixFunction fixer;
                                                *assertion = (*assertion )->acceptMutator( fixer );
                                                if ( fixer.get_isVoid() ) {
                                                        throw SemanticError( "invalid type void in assertion of function ", func );
                                                }
                                                (*type )->get_assertions().push_back( *assertion );
                                        } // if
                                } // for
                                toBeDone.clear();
                                toBeDone.splice( toBeDone.end(), nextRound );
                        } // while
                } // for
        }

        void Pass3::visit( ObjectDecl *object ) {
                forallFixer( object->get_type() );
                if ( PointerType *pointer = dynamic_cast< PointerType * >( object->get_type() ) ) {
                        forallFixer( pointer->get_base() );
                } // if
                Parent::visit( object );
                object->fixUniqueId();
        }

        void Pass3::visit( FunctionDecl *func ) {
                forallFixer( func->get_type() );
                Parent::visit( func );
                func->fixUniqueId();
        }

        static const std::list< std::string > noLabels;

        void AutogenerateRoutines::autogenerateRoutines( std::list< Declaration * > &translationUnit ) {
                AutogenerateRoutines visitor;
                acceptAndAdd( translationUnit, visitor, false );
        }

        template< typename OutputIterator >
        void makeScalarFunction( ObjectDecl *srcParam, ObjectDecl *dstParam, DeclarationWithType *member, std::string fname, OutputIterator out ) {
                ObjectDecl *obj = dynamic_cast<ObjectDecl *>( member );
                // unnamed bit fields are not copied as they cannot be accessed
                if ( obj != NULL && obj->get_name() == "" && obj->get_bitfieldWidth() != NULL ) return;

                // want to be able to generate assignment, ctor, and dtor generically,
                // so fname is either ?=?, ?{}, or ^?{}
                UntypedExpr *fExpr = new UntypedExpr( new NameExpr( fname ) );

                UntypedExpr *derefExpr = new UntypedExpr( new NameExpr( "*?" ) );
                derefExpr->get_args().push_back( new VariableExpr( dstParam ) );

                // do something special for unnamed members
                Expression *dstselect = new AddressExpr( new MemberExpr( member, derefExpr ) );
                fExpr->get_args().push_back( dstselect );

                Expression *srcselect = new MemberExpr( member, new VariableExpr( srcParam ) );
                fExpr->get_args().push_back( srcselect );

                *out++ = new ExprStmt( noLabels, fExpr );
        }

        template< typename OutputIterator >
        void makeArrayFunction( ObjectDecl *srcParam, ObjectDecl *dstParam, DeclarationWithType *member, ArrayType *array, std::string fname, OutputIterator out ) {
                static UniqueName indexName( "_index" );

                // for a flexible array member nothing is done -- user must define own assignment
                if ( ! array->get_dimension() ) return;

                ObjectDecl *index = new ObjectDecl( indexName.newName(), DeclarationNode::NoStorageClass, LinkageSpec::C, 0, new BasicType( Type::Qualifiers(), BasicType::SignedInt ), 0 );
                *out++ = new DeclStmt( noLabels, index );

                UntypedExpr *init = new UntypedExpr( new NameExpr( "?=?" ) );
                init->get_args().push_back( new AddressExpr( new VariableExpr( index ) ) );
                init->get_args().push_back( new NameExpr( "0" ) );
                Statement *initStmt = new ExprStmt( noLabels, init );
                std::list<Statement *> initList;
                initList.push_back( initStmt );

                UntypedExpr *cond = new UntypedExpr( new NameExpr( "?<?" ) );
                cond->get_args().push_back( new VariableExpr( index ) );
                cond->get_args().push_back( array->get_dimension()->clone() );

                UntypedExpr *inc = new UntypedExpr( new NameExpr( "++?" ) );
                inc->get_args().push_back( new AddressExpr( new VariableExpr( index ) ) );

                // want to be able to generate assignment, ctor, and dtor generically,
                // so fname is either ?=?, ?{}, or ^?{}
                UntypedExpr *fExpr = new UntypedExpr( new NameExpr( fname ) );

                UntypedExpr *derefExpr = new UntypedExpr( new NameExpr( "*?" ) );
                derefExpr->get_args().push_back( new VariableExpr( dstParam ) );

                Expression *dstselect = new MemberExpr( member, derefExpr );
                UntypedExpr *dstIndex = new UntypedExpr( new NameExpr( "?+?" ) );
                dstIndex->get_args().push_back( dstselect );
                dstIndex->get_args().push_back( new VariableExpr( index ) );
                fExpr->get_args().push_back( dstIndex );

                Expression *srcselect = new MemberExpr( member, new VariableExpr( srcParam ) );
                UntypedExpr *srcIndex = new UntypedExpr( new NameExpr( "?[?]" ) );
                srcIndex->get_args().push_back( srcselect );
                srcIndex->get_args().push_back( new VariableExpr( index ) );
                fExpr->get_args().push_back( srcIndex );

                *out++ = new ForStmt( noLabels, initList, cond, inc, new ExprStmt( noLabels, fExpr ) );
        }

        template< typename OutputIterator >
        void makeUnionFieldsAssignment( ObjectDecl *srcParam, ObjectDecl *dstParam, UnionInstType *unionType, OutputIterator out ) {
                UntypedExpr *copy = new UntypedExpr( new NameExpr( "__builtin_memcpy" ) );
                copy->get_args().push_back( new VariableExpr( dstParam ) );
                copy->get_args().push_back( new AddressExpr( new VariableExpr( srcParam ) ) );
                copy->get_args().push_back( new SizeofExpr( unionType ) );

                *out++ = new ExprStmt( noLabels, copy );
        }

        //E ?=?(E volatile*, int),
        //  ?=?(E _Atomic volatile*, int);
        void makeEnumAssignment( EnumDecl *enumDecl, EnumInstType *refType, unsigned int functionNesting, std::list< Declaration * > &declsToAdd ) {
                FunctionType *assignType = new FunctionType( Type::Qualifiers(), false );

                ObjectDecl *returnVal = new ObjectDecl( "", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, refType->clone(), 0 );
                assignType->get_returnVals().push_back( returnVal );

                // need two assignment operators with different types
                FunctionType * assignType2 = assignType->clone();

                // E ?=?(E volatile *, E)
                Type *etype = refType->clone();
                // etype->get_qualifiers() += Type::Qualifiers(false, true, false, false, false, false);

                ObjectDecl *dstParam = new ObjectDecl( "_dst", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, new PointerType( Type::Qualifiers(), etype ), 0 );
                assignType->get_parameters().push_back( dstParam );

                ObjectDecl *srcParam = new ObjectDecl( "_src", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, etype->clone(), 0 );
                assignType->get_parameters().push_back( srcParam );

                // E ?=?(E volatile *, int)
                assignType2->get_parameters().push_back( dstParam->clone() );
                BasicType * paramType = new BasicType(Type::Qualifiers(), BasicType::SignedInt);
                ObjectDecl *srcParam2 = new ObjectDecl( "_src", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, paramType, 0 );
                assignType2->get_parameters().push_back( srcParam2 );

                // Routines at global scope marked "static" to prevent multiple definitions is separate translation units
                // because each unit generates copies of the default routines for each aggregate.

                // since there is no definition, these should not be inline
                // make these intrinsic so that the code generator does not make use of them
                FunctionDecl *assignDecl = new FunctionDecl( "?=?", functionNesting > 0 ? DeclarationNode::NoStorageClass : DeclarationNode::Static, LinkageSpec::Intrinsic, assignType, 0, false, false );
                assignDecl->fixUniqueId();
                FunctionDecl *assignDecl2 = new FunctionDecl( "?=?", functionNesting > 0 ? DeclarationNode::NoStorageClass : DeclarationNode::Static, LinkageSpec::Intrinsic, assignType2, 0, false, false );
                assignDecl2->fixUniqueId();

                // these should be built in the same way that the prelude
                // functions are, so build a list containing the prototypes
                // and allow MakeLibCfa to autogenerate the bodies.
                std::list< Declaration * > assigns;
                assigns.push_back( assignDecl );
                assigns.push_back( assignDecl2 );

                LibCfa::makeLibCfa( assigns );

                // need to remove the prototypes, since this may be nested in a routine
                for (int start = 0, end = assigns.size()/2; start < end; start++) {
                        delete assigns.front();
                        assigns.pop_front();
                } // for

                declsToAdd.insert( declsToAdd.begin(), assigns.begin(), assigns.end() );
        }

        /// Clones a reference type, replacing any parameters it may have with a clone of the provided list
        template< typename GenericInstType >
        GenericInstType *cloneWithParams( GenericInstType *refType, const std::list< Expression* >& params ) {
                GenericInstType *clone = refType->clone();
                clone->get_parameters().clear();
                cloneAll( params, clone->get_parameters() );
                return clone;
        }

        /// Creates a new type decl that's the same as src, but renamed and with only the ?=? assertion (for complete types only)
        TypeDecl *cloneAndRename( TypeDecl *src, const std::string &name ) {
                TypeDecl *dst = new TypeDecl( name, src->get_storageClass(), 0, src->get_kind() );

                if ( src->get_kind() == TypeDecl::Any ) {
                        // just include assignment operator assertion
                        TypeInstType *assignParamType = new TypeInstType( Type::Qualifiers(), name, dst );
                        FunctionType *assignFunctionType = new FunctionType( Type::Qualifiers(), false );
                        assignFunctionType->get_returnVals().push_back(
                                new ObjectDecl( "", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, assignParamType->clone(), 0 ) );
                        assignFunctionType->get_parameters().push_back(
                                new ObjectDecl( "", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, new PointerType( Type::Qualifiers(), assignParamType->clone() ), 0 ) );
                        assignFunctionType->get_parameters().push_back(
                                new ObjectDecl( "", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, assignParamType, 0 ) );
                        FunctionDecl *assignAssert = new FunctionDecl( "?=?", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, assignFunctionType, 0, false, false );
                        dst->get_assertions().push_back( assignAssert );
                }

                return dst;
        }

        Declaration *makeStructAssignment( StructDecl *aggregateDecl, StructInstType *refType, unsigned int functionNesting ) {
                FunctionType *assignType = new FunctionType( Type::Qualifiers(), false );

                // Make function polymorphic in same parameters as generic struct, if applicable
                bool isGeneric = false;  // NOTE this flag is an incredibly ugly kludge; we should fix the assignment signature instead (ditto for union)
                std::list< TypeDecl* >& genericParams = aggregateDecl->get_parameters();
                std::list< Expression* > structParams;  // List of matching parameters to put on types
                TypeSubstitution genericSubs; // Substitutions to make to member types of struct
                for ( std::list< TypeDecl* >::const_iterator param = genericParams.begin(); param != genericParams.end(); ++param ) {
                        isGeneric = true;
                        TypeDecl *typeParam = cloneAndRename( *param, "_autoassign_" + aggregateDecl->get_name() + "_" + (*param)->get_name() );
                        assignType->get_forall().push_back( typeParam );
                        TypeInstType *newParamType = new TypeInstType( Type::Qualifiers(), typeParam->get_name(), typeParam );
                        genericSubs.add( (*param)->get_name(), newParamType );
                        structParams.push_back( new TypeExpr( newParamType ) );
                }

                ObjectDecl *returnVal = new ObjectDecl( "_ret", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, cloneWithParams( refType, structParams ), 0 );
                assignType->get_returnVals().push_back( returnVal );

                ObjectDecl *dstParam = new ObjectDecl( "_dst", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, new PointerType( Type::Qualifiers(), cloneWithParams( refType, structParams ) ), 0 );
                assignType->get_parameters().push_back( dstParam );

                ObjectDecl *srcParam = new ObjectDecl( "_src", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, cloneWithParams( refType, structParams ), 0 );
                assignType->get_parameters().push_back( srcParam );

                // Routines at global scope marked "static" to prevent multiple definitions is separate translation units
                // because each unit generates copies of the default routines for each aggregate.
                FunctionDecl *assignDecl = new FunctionDecl( "?=?", functionNesting > 0 ? DeclarationNode::NoStorageClass : DeclarationNode::Static, LinkageSpec::AutoGen, assignType, new CompoundStmt( noLabels ), true, false );
                assignDecl->fixUniqueId();

                for ( std::list< Declaration * >::const_iterator member = aggregateDecl->get_members().begin(); member != aggregateDecl->get_members().end(); ++member ) {
                        if ( DeclarationWithType *dwt = dynamic_cast< DeclarationWithType * >( *member ) ) {
                                // query the type qualifiers of this field and skip assigning it if it is marked const.
                                // If it is an array type, we need to strip off the array layers to find its qualifiers.
                                Type * type = dwt->get_type();
                                while ( ArrayType * at = dynamic_cast< ArrayType * >( type ) ) {
                                        type = at->get_base();
                                }

                                if ( type->get_qualifiers().isConst ) {
                                        // don't assign const members
                                        continue;
                                }

                                if ( isGeneric ) {
                                        // rewrite member type in terms of the type variables on this operator
                                        DeclarationWithType *fixedMember = dwt->clone();
                                        genericSubs.apply( fixedMember );

                                        // assign to both destination and return value
                                        if ( ArrayType *array = dynamic_cast< ArrayType * >( fixedMember->get_type() ) ) {
                                                makeArrayFunction( srcParam, dstParam, fixedMember, array, "?=?", back_inserter( assignDecl->get_statements()->get_kids() ) );
                                                makeArrayFunction( srcParam, returnVal, fixedMember, array, "?=?", back_inserter( assignDecl->get_statements()->get_kids() ) );
                                        } else {
                                                makeScalarFunction( srcParam, dstParam, fixedMember, "?=?", back_inserter( assignDecl->get_statements()->get_kids() ) );
                                                makeScalarFunction( srcParam, returnVal, fixedMember, "?=?", back_inserter( assignDecl->get_statements()->get_kids() ) );
                                        } // if
                                } else {
                                        // assign to destination
                                        if ( ArrayType *array = dynamic_cast< ArrayType * >( dwt->get_type() ) ) {
                                                makeArrayFunction( srcParam, dstParam, dwt, array, "?=?", back_inserter( assignDecl->get_statements()->get_kids() ) );
                                        } else {
                                                makeScalarFunction( srcParam, dstParam, dwt, "?=?", back_inserter( assignDecl->get_statements()->get_kids() ) );
                                        } // if
                                } // if
                        } // if
                } // for
                if ( ! isGeneric ) assignDecl->get_statements()->get_kids().push_back( new ReturnStmt( noLabels, new VariableExpr( srcParam ) ) );

                return assignDecl;
        }

        void makeStructCtorDtor( StructDecl *aggregateDecl, StructInstType *refType, unsigned int functionNesting, std::list< Declaration * > & declsToAdd ) {
                FunctionType *ctorType = new FunctionType( Type::Qualifiers(), false );

                // Make function polymorphic in same parameters as generic struct, if applicable
                bool isGeneric = false;  // NOTE this flag is an incredibly ugly kludge; we should fix the assignment signature instead (ditto for union)
                std::list< TypeDecl* >& genericParams = aggregateDecl->get_parameters();
                std::list< Expression* > structParams;  // List of matching parameters to put on types
                for ( std::list< TypeDecl* >::const_iterator param = genericParams.begin(); param != genericParams.end(); ++param ) {
                        isGeneric = true;
                        TypeDecl *typeParam = (*param)->clone();
                        ctorType->get_forall().push_back( typeParam );
                        structParams.push_back( new TypeExpr( new TypeInstType( Type::Qualifiers(), typeParam->get_name(), typeParam ) ) );
                }

                ObjectDecl *thisParam = new ObjectDecl( "_this", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, new PointerType( Type::Qualifiers(), cloneWithParams( refType, structParams ) ), 0 );
                ctorType->get_parameters().push_back( thisParam );

                // Routines at global scope marked "static" to prevent multiple definitions is separate translation units
                // because each unit generates copies of the default routines for each aggregate.
                FunctionDecl *ctorDecl = new FunctionDecl( "?{}", functionNesting > 0 ? DeclarationNode::NoStorageClass : DeclarationNode::Static, LinkageSpec::AutoGen, ctorType, 0, true, false );
                FunctionDecl *copyCtorDecl = new FunctionDecl( "?{}", functionNesting > 0 ? DeclarationNode::NoStorageClass : DeclarationNode::Static, LinkageSpec::AutoGen, ctorType->clone(), 0, true, false );
                FunctionDecl *dtorDecl = new FunctionDecl( "^?{}", functionNesting > 0 ? DeclarationNode::NoStorageClass : DeclarationNode::Static, LinkageSpec::AutoGen, ctorType->clone(), 0, true, false );
                ctorDecl->fixUniqueId();
                copyCtorDecl->fixUniqueId();
                dtorDecl->fixUniqueId();

                // add definitions
                // TODO: add in calls to default constructors and destructors for fields
                ctorDecl->set_statements( new CompoundStmt( noLabels ) );
                copyCtorDecl->set_statements( new CompoundStmt( noLabels ) );
                dtorDecl->set_statements( new CompoundStmt( noLabels ) );
                declsToAdd.push_back( ctorDecl );
                declsToAdd.push_back( copyCtorDecl );
                declsToAdd.push_back( dtorDecl );

                ObjectDecl * srcParam = new ObjectDecl( "_other", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, cloneWithParams( refType, structParams ), 0 );
                copyCtorDecl->get_functionType()->get_parameters().push_back( srcParam );
                for ( std::list< Declaration * >::const_iterator member = aggregateDecl->get_members().begin(); member != aggregateDecl->get_members().end(); ++member ) {
                        if ( DeclarationWithType *dwt = dynamic_cast< DeclarationWithType * >( *member ) ) {
                                // query the type qualifiers of this field and skip assigning it if it is marked const.
                                // If it is an array type, we need to strip off the array layers to find its qualifiers.
                                Type * type = dwt->get_type();
                                while ( ArrayType * at = dynamic_cast< ArrayType * >( type ) ) {
                                        type = at->get_base();
                                }

                                if ( type->get_qualifiers().isConst ) {
                                        // don't assign const members
                                        continue;
                                }

                                if ( ArrayType *array = dynamic_cast< ArrayType * >( dwt->get_type() ) ) {
                                        makeArrayFunction( srcParam, thisParam, dwt, array, "?{}", back_inserter( copyCtorDecl->get_statements()->get_kids() ) );
                                        // if ( isGeneric ) makeArrayFunction( srcParam, returnVal, dwt, array, back_inserter( copyCtorDecl->get_statements()->get_kids() ) );
                                } else {
                                        makeScalarFunction( srcParam, thisParam, dwt, "?{}", back_inserter( copyCtorDecl->get_statements()->get_kids() ) );
                                        // if ( isGeneric ) makeScalarCtor( srcParam, returnVal, dwt, back_inserter( copyCtorDecl->get_statements()->get_kids() ) );
                                } // if
                        } // if
                } // for
                // if ( ! isGeneric ) assignDecl->get_statements()->get_kids().push_back( new ReturnStmt( noLabels, new VariableExpr( srcParam ) ) );
        }

        void makeUnionFunctions( UnionDecl *aggregateDecl, UnionInstType *refType, unsigned int functionNesting, std::list< Declaration * > & declsToAdd ) {
                FunctionType *assignType = new FunctionType( Type::Qualifiers(), false );

                // Make function polymorphic in same parameters as generic union, if applicable
                bool isGeneric = false;  // NOTE this flag is an incredibly ugly kludge; we should fix the assignment signature instead (ditto for struct)
                std::list< TypeDecl* >& genericParams = aggregateDecl->get_parameters();
                std::list< Expression* > unionParams;  // List of matching parameters to put on types
                for ( std::list< TypeDecl* >::const_iterator param = genericParams.begin(); param != genericParams.end(); ++param ) {
                        isGeneric = true;
                        TypeDecl *typeParam = cloneAndRename( *param, "_autoassign_" + aggregateDecl->get_name() + "_" + (*param)->get_name() );
                        assignType->get_forall().push_back( typeParam );
                        unionParams.push_back( new TypeExpr( new TypeInstType( Type::Qualifiers(), typeParam->get_name(), typeParam ) ) );
                }

                ObjectDecl *dstParam = new ObjectDecl( "_dst", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, new PointerType( Type::Qualifiers(), cloneWithParams( refType, unionParams ) ), 0 );
                assignType->get_parameters().push_back( dstParam );

                // default ctor/dtor need only first parameter
                FunctionType * ctorType = assignType->clone();
                FunctionType * dtorType = assignType->clone();

                ObjectDecl *srcParam = new ObjectDecl( "_src", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, cloneWithParams( refType, unionParams ), 0 );
                assignType->get_parameters().push_back( srcParam );

                // copy ctor needs both parameters
                FunctionType * copyCtorType = assignType->clone();

                // assignment needs both and return value
                ObjectDecl *returnVal = new ObjectDecl( "_ret", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, cloneWithParams( refType, unionParams ), 0 );
                assignType->get_returnVals().push_back( returnVal );

                // Routines at global scope marked "static" to prevent multiple definitions is separate translation units
                // because each unit generates copies of the default routines for each aggregate.
                FunctionDecl *assignDecl = new FunctionDecl( "?=?",  functionNesting > 0 ? DeclarationNode::NoStorageClass : DeclarationNode::Static, LinkageSpec::AutoGen, assignType, new CompoundStmt( noLabels ), true, false );
                FunctionDecl *ctorDecl = new FunctionDecl( "?{}",  functionNesting > 0 ? DeclarationNode::NoStorageClass : DeclarationNode::Static, LinkageSpec::AutoGen, ctorType, new CompoundStmt( noLabels ), true, false );
                FunctionDecl *copyCtorDecl = new FunctionDecl( "?{}",  functionNesting > 0 ? DeclarationNode::NoStorageClass : DeclarationNode::Static, LinkageSpec::AutoGen, copyCtorType, NULL, true, false );
                FunctionDecl *dtorDecl = new FunctionDecl( "^?{}",  functionNesting > 0 ? DeclarationNode::NoStorageClass : DeclarationNode::Static, LinkageSpec::AutoGen, dtorType, new CompoundStmt( noLabels ), true, false );

                assignDecl->fixUniqueId();
                ctorDecl->fixUniqueId();
                copyCtorDecl->fixUniqueId();
                dtorDecl->fixUniqueId();

                makeUnionFieldsAssignment( srcParam, dstParam, cloneWithParams( refType, unionParams ), back_inserter( assignDecl->get_statements()->get_kids() ) );
                if ( isGeneric ) makeUnionFieldsAssignment( srcParam, returnVal, cloneWithParams( refType, unionParams ), back_inserter( assignDecl->get_statements()->get_kids() ) );

                if ( ! isGeneric ) assignDecl->get_statements()->get_kids().push_back( new ReturnStmt( noLabels, new VariableExpr( srcParam ) ) );

                // body of assignment and copy ctor is the same
                copyCtorDecl->set_statements( assignDecl->get_statements()->clone() );

                declsToAdd.push_back( assignDecl );
                declsToAdd.push_back( ctorDecl );
                declsToAdd.push_back( copyCtorDecl );
                declsToAdd.push_back( dtorDecl );
        }

        void AutogenerateRoutines::visit( EnumDecl *enumDecl ) {
                if ( ! enumDecl->get_members().empty() ) {
                        EnumInstType *enumInst = new EnumInstType( Type::Qualifiers(), enumDecl->get_name() );
                        // enumInst->set_baseEnum( enumDecl );
                        // declsToAdd.push_back(
                        makeEnumAssignment( enumDecl, enumInst, functionNesting, declsToAdd );
                }
        }

        void AutogenerateRoutines::visit( StructDecl *structDecl ) {
                if ( ! structDecl->get_members().empty() && structsDone.find( structDecl->get_name() ) == structsDone.end() ) {
                        StructInstType structInst( Type::Qualifiers(), structDecl->get_name() );
                        structInst.set_baseStruct( structDecl );

                        declsToAdd.push_back( makeStructAssignment( structDecl, &structInst, functionNesting ) );
                        makeStructCtorDtor( structDecl, &structInst, functionNesting, declsToAdd );
                        structsDone.insert( structDecl->get_name() );
                } // if
        }

        void AutogenerateRoutines::visit( UnionDecl *unionDecl ) {
                if ( ! unionDecl->get_members().empty() ) {
                        UnionInstType unionInst( Type::Qualifiers(), unionDecl->get_name() );
                        unionInst.set_baseUnion( unionDecl );
                        makeUnionFunctions( unionDecl, &unionInst, functionNesting, declsToAdd );
                } // if
        }

        void AutogenerateRoutines::visit( TypeDecl *typeDecl ) {
                CompoundStmt *stmts = 0;
                TypeInstType *typeInst = new TypeInstType( Type::Qualifiers(), typeDecl->get_name(), false );
                typeInst->set_baseType( typeDecl );
                ObjectDecl *src = new ObjectDecl( "_src", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, typeInst->clone(), 0 );
                ObjectDecl *dst = new ObjectDecl( "_dst", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, new PointerType( Type::Qualifiers(), typeInst->clone() ), 0 );
                if ( typeDecl->get_base() ) {
                        stmts = new CompoundStmt( std::list< Label >() );
                        UntypedExpr *assign = new UntypedExpr( new NameExpr( "?=?" ) );
                        assign->get_args().push_back( new CastExpr( new VariableExpr( dst ), new PointerType( Type::Qualifiers(), typeDecl->get_base()->clone() ) ) );
                        assign->get_args().push_back( new CastExpr( new VariableExpr( src ), typeDecl->get_base()->clone() ) );
                        stmts->get_kids().push_back( new ReturnStmt( std::list< Label >(), assign ) );
                } // if
                FunctionType *type = new FunctionType( Type::Qualifiers(), false );
                type->get_returnVals().push_back( new ObjectDecl( "", DeclarationNode::NoStorageClass, LinkageSpec::Cforall, 0, typeInst, 0 ) );
                type->get_parameters().push_back( dst );
                type->get_parameters().push_back( src );
                FunctionDecl *func = new FunctionDecl( "?=?", DeclarationNode::NoStorageClass, LinkageSpec::AutoGen, type, stmts, false, false );
                declsToAdd.push_back( func );
        }

        void addDecls( std::list< Declaration * > &declsToAdd, std::list< Statement * > &statements, std::list< Statement * >::iterator i ) {
                for ( std::list< Declaration * >::iterator decl = declsToAdd.begin(); decl != declsToAdd.end(); ++decl ) {
                        statements.insert( i, new DeclStmt( noLabels, *decl ) );
                } // for
                declsToAdd.clear();
        }

        void AutogenerateRoutines::visit( FunctionType *) {
                // ensure that we don't add assignment ops for types defined as part of the function
        }

        void AutogenerateRoutines::visit( PointerType *) {
                // ensure that we don't add assignment ops for types defined as part of the pointer
        }

        void AutogenerateRoutines::visit( ContextDecl *) {
                // ensure that we don't add assignment ops for types defined as part of the context
        }

        template< typename StmtClass >
        inline void AutogenerateRoutines::visitStatement( StmtClass *stmt ) {
                std::set< std::string > oldStructs = structsDone;
                addVisit( stmt, *this );
                structsDone = oldStructs;
        }

        void AutogenerateRoutines::visit( FunctionDecl *functionDecl ) {
                maybeAccept( functionDecl->get_functionType(), *this );
                acceptAll( functionDecl->get_oldDecls(), *this );
                functionNesting += 1;
                maybeAccept( functionDecl->get_statements(), *this );
                functionNesting -= 1;
        }

        void AutogenerateRoutines::visit( CompoundStmt *compoundStmt ) {
                visitStatement( compoundStmt );
        }

        void AutogenerateRoutines::visit( IfStmt *ifStmt ) {
                visitStatement( ifStmt );
        }

        void AutogenerateRoutines::visit( WhileStmt *whileStmt ) {
                visitStatement( whileStmt );
        }

        void AutogenerateRoutines::visit( ForStmt *forStmt ) {
                visitStatement( forStmt );
        }

        void AutogenerateRoutines::visit( SwitchStmt *switchStmt ) {
                visitStatement( switchStmt );
        }

        void AutogenerateRoutines::visit( ChooseStmt *switchStmt ) {
                visitStatement( switchStmt );
        }

        void AutogenerateRoutines::visit( CaseStmt *caseStmt ) {
                visitStatement( caseStmt );
        }

        void AutogenerateRoutines::visit( CatchStmt *cathStmt ) {
                visitStatement( cathStmt );
        }

        void ReturnChecker::checkFunctionReturns( std::list< Declaration * > & translationUnit ) {
                ReturnChecker checker;
                acceptAll( translationUnit, checker );
        }

        void ReturnChecker::visit( FunctionDecl * functionDecl ) {
                std::list< DeclarationWithType * > oldReturnVals = returnVals;
                returnVals = functionDecl->get_functionType()->get_returnVals();
                Visitor::visit( functionDecl );
                returnVals = oldReturnVals;
        }

        void ReturnChecker::visit( ReturnStmt * returnStmt ) {
                if ( returnStmt->get_expr() == NULL && returnVals.size() != 0 ) {
                        throw SemanticError( "Non-void function returns no values: " , returnStmt );
                } else if ( returnStmt->get_expr() != NULL && returnVals.size() == 0 ) {
                        throw SemanticError( "void function returns values: " , returnStmt );
                }
        }


        bool isTypedef( Declaration *decl ) {
                return dynamic_cast< TypedefDecl * >( decl );
        }

        void EliminateTypedef::eliminateTypedef( std::list< Declaration * > &translationUnit ) {
                EliminateTypedef eliminator;
                mutateAll( translationUnit, eliminator );
                filter( translationUnit, isTypedef, true );
        }

        Type *EliminateTypedef::mutate( TypeInstType * typeInst ) {
                // instances of typedef types will come here. If it is an instance
                // of a typdef type, link the instance to its actual type.
                TypedefMap::const_iterator def = typedefNames.find( typeInst->get_name() );
                if ( def != typedefNames.end() ) {
                        Type *ret = def->second.first->get_base()->clone();
                        ret->get_qualifiers() += typeInst->get_qualifiers();
                        // place instance parameters on the typedef'd type
                        if ( ! typeInst->get_parameters().empty() ) {
                                ReferenceToType *rtt = dynamic_cast<ReferenceToType*>(ret);
                                if ( ! rtt ) {
                                        throw SemanticError("cannot apply type parameters to base type of " + typeInst->get_name());
                                }
                                rtt->get_parameters().clear();
                                cloneAll(typeInst->get_parameters(), rtt->get_parameters());
                        } // if
                        delete typeInst;
                        return ret;
                } // if
                return typeInst;
        }

        Declaration *EliminateTypedef::mutate( TypedefDecl * tyDecl ) {
                Declaration *ret = Mutator::mutate( tyDecl );
                if ( typedefNames.count( tyDecl->get_name() ) == 1 && typedefNames[ tyDecl->get_name() ].second == scopeLevel ) {
                        // typedef to the same name from the same scope
                        // must be from the same type

                        Type * t1 = tyDecl->get_base();
                        Type * t2 = typedefNames[ tyDecl->get_name() ].first->get_base();
                        if ( ! ResolvExpr::typesCompatible( t1, t2, Indexer() ) ) {
                                throw SemanticError( "cannot redefine typedef: " + tyDecl->get_name() );
                        }
                } else {
                        typedefNames[ tyDecl->get_name() ] = std::make_pair( tyDecl, scopeLevel );
                } // if

                // When a typedef is a forward declaration:
                //    typedef struct screen SCREEN;
                // the declaration portion must be retained:
                //    struct screen;
                // because the expansion of the typedef is:
                //    void rtn( SCREEN *p ) => void rtn( struct screen *p )
                // hence the type-name "screen" must be defined.
                // Note, qualifiers on the typedef are superfluous for the forward declaration.
                if ( StructInstType *aggDecl = dynamic_cast< StructInstType * >( tyDecl->get_base() ) ) {
                        return new StructDecl( aggDecl->get_name() );
                } else if ( UnionInstType *aggDecl = dynamic_cast< UnionInstType * >( tyDecl->get_base() ) ) {
                        return new UnionDecl( aggDecl->get_name() );
                } else {
                        return ret;
                } // if
        }

        TypeDecl *EliminateTypedef::mutate( TypeDecl * typeDecl ) {
                TypedefMap::iterator i = typedefNames.find( typeDecl->get_name() );
                if ( i != typedefNames.end() ) {
                        typedefNames.erase( i ) ;
                } // if
                return typeDecl;
        }

        DeclarationWithType *EliminateTypedef::mutate( FunctionDecl * funcDecl ) {
                TypedefMap oldNames = typedefNames;
                DeclarationWithType *ret = Mutator::mutate( funcDecl );
                typedefNames = oldNames;
                return ret;
        }

        DeclarationWithType *EliminateTypedef::mutate( ObjectDecl * objDecl ) {
                TypedefMap oldNames = typedefNames;
                DeclarationWithType *ret = Mutator::mutate( objDecl );
                typedefNames = oldNames;
                // is the type a function?
                if ( FunctionType *funtype = dynamic_cast<FunctionType *>( ret->get_type() ) ) {
                        // replace the current object declaration with a function declaration
                        return new FunctionDecl( ret->get_name(), ret->get_storageClass(), ret->get_linkage(), funtype, 0, ret->get_isInline(), ret->get_isNoreturn() );
                } else if ( objDecl->get_isInline() || objDecl->get_isNoreturn() ) {
                        throw SemanticError( "invalid inline or _Noreturn specification in declaration of ", objDecl );
                } // if
                return ret;
        }

        Expression *EliminateTypedef::mutate( CastExpr * castExpr ) {
                TypedefMap oldNames = typedefNames;
                Expression *ret = Mutator::mutate( castExpr );
                typedefNames = oldNames;
                return ret;
        }

        CompoundStmt *EliminateTypedef::mutate( CompoundStmt * compoundStmt ) {
                TypedefMap oldNames = typedefNames;
                scopeLevel += 1;
                CompoundStmt *ret = Mutator::mutate( compoundStmt );
                scopeLevel -= 1;
                std::list< Statement * >::iterator i = compoundStmt->get_kids().begin();
                while ( i != compoundStmt->get_kids().end() ) {
                        std::list< Statement * >::iterator next = i+1;
                        if ( DeclStmt *declStmt = dynamic_cast< DeclStmt * >( *i ) ) {
                                if ( dynamic_cast< TypedefDecl * >( declStmt->get_decl() ) ) {
                                        delete *i;
                                        compoundStmt->get_kids().erase( i );
                                } // if
                        } // if
                        i = next;
                } // while
                typedefNames = oldNames;
                return ret;
        }

        // there may be typedefs nested within aggregates
        // in order for everything to work properly, these
        // should be removed as well
        template<typename AggDecl>
        AggDecl *EliminateTypedef::handleAggregate( AggDecl * aggDecl ) {
                std::list<Declaration *>::iterator it = aggDecl->get_members().begin();
                for ( ; it != aggDecl->get_members().end(); ) {
                        std::list< Declaration * >::iterator next = it+1;
                        if ( dynamic_cast< TypedefDecl * >( *it ) ) {
                                delete *it;
                                aggDecl->get_members().erase( it );
                        } // if
                        it = next;
                }
                return aggDecl;
        }

        Declaration *EliminateTypedef::mutate( StructDecl * structDecl ) {
                Mutator::mutate( structDecl );
                return handleAggregate( structDecl );
        }

        Declaration *EliminateTypedef::mutate( UnionDecl * unionDecl ) {
                Mutator::mutate( unionDecl );
                return handleAggregate( unionDecl );
        }

        Declaration *EliminateTypedef::mutate( EnumDecl * enumDecl ) {
                Mutator::mutate( enumDecl );
                return handleAggregate( enumDecl );
        }

                Declaration *EliminateTypedef::mutate( ContextDecl * contextDecl ) {
                Mutator::mutate( contextDecl );
                return handleAggregate( contextDecl );
        }

        void VerifyCtorDtor::verify( std::list< Declaration * > & translationUnit ) {
                VerifyCtorDtor verifier;
                acceptAll( translationUnit, verifier );
        }

        void VerifyCtorDtor::visit( FunctionDecl * funcDecl ) {
                FunctionType * funcType = funcDecl->get_functionType();
                std::list< DeclarationWithType * > &returnVals = funcType->get_returnVals();
                std::list< DeclarationWithType * > &params = funcType->get_parameters();

                if ( funcDecl->get_name() == "?{}" || funcDecl->get_name() == "^?{}" ) {
                        if ( params.size() == 0 ) {
                                throw SemanticError( "Constructors and destructors require at least one parameter ", funcDecl );
                        }
                        if ( ! dynamic_cast< PointerType * >( params.front()->get_type() ) ) {
                                throw SemanticError( "First parameter of a constructor or destructor must be a pointer ", funcDecl );
                        }
                        if ( returnVals.size() != 0 ) {
                                throw SemanticError( "Constructors and destructors cannot have explicit return values ", funcDecl );
                        }
                }

                Visitor::visit( funcDecl );
                // original idea: modify signature of ctor/dtors and insert appropriate return statements
                // to cause desired behaviour
                // new idea: add comma exprs to every ctor call to produce first parameter.
                // this requires some memoization of the first parameter, because it can be a
                // complicated expression with side effects (see: malloc). idea: add temporary variable
                // that is assigned address of constructed object in ctor argument position and
                // return the temporary. It should also be done after all implicit ctors are
                // added, so not in this pass!
        }
} // namespace SymTab

// Local Variables: //
// tab-width: 4 //
// mode: c++ //
// compile-command: "make install" //
// End: //