source: src/SymTab/Validate.cc @ f43a200

//
// 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 : Wed May 11 13:17:52 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 "Common/utility.h"
#include "Common/UniqueName.h"
#include "Validate.h"
#include "SynTree/Visitor.h"
#include "SynTree/Mutator.h"
#include "SynTree/Type.h"
#include "SynTree/Expression.h"
#include "SynTree/Statement.h"
#include "SynTree/TypeSubstitution.h"
#include "Indexer.h"
#include "FixFunction.h"
// #include "ImplementationType.h"
#include "GenPoly/DeclMutator.h"
#include "AddVisit.h"
#include "MakeLibCfa.h"
#include "TypeEquality.h"
#include "Autogen.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( SwitchStmt *switchStmt );
                virtual void visit( ChooseStmt *chooseStmt );
                // virtual void visit( CaseStmt *caseStmt );
          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( TraitInstType *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 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( TraitDecl * contextDecl );

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

                template<typename AggDecl>
                void addImplicitTypedef( 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 );

                virtual void visit( FunctionDecl *funcDecl );
};

        class CompoundLiteral : public GenPoly::DeclMutator {
                DeclarationNode::StorageClass storageclass = DeclarationNode::NoStorageClass;

                virtual DeclarationWithType * mutate( ObjectDecl *objectDecl );
                virtual Expression *mutate( CompoundLiteralExpr *compLitExpr );
        };

        void validate( std::list< Declaration * > &translationUnit, bool doDebug ) {
                Pass1 pass1;
                Pass2 pass2( doDebug, 0 );
                Pass3 pass3( 0 );
                CompoundLiteral compoundliteral;

                EliminateTypedef::eliminateTypedef( translationUnit );
                HoistStruct::hoistStruct( translationUnit );
                acceptAll( translationUnit, pass1 );
                acceptAll( translationUnit, pass2 );
                ReturnChecker::checkFunctionReturns( translationUnit );
                mutateAll( translationUnit, compoundliteral );
                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 );
        }

        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( SwitchStmt *switchStmt ) {
                addVisit( switchStmt, *this );
        }

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

        // void HoistStruct::visit( CaseStmt *caseStmt ) {
        //      addVisit( caseStmt, *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( TraitInstType *contextInst ) {
                Parent::visit( contextInst );
                TraitDecl *ctx = indexer->lookupTrait( 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 ( TraitInstType *otherCtx = dynamic_cast< TraitInstType * >(*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 ) {
                // visit struct members first so that the types of self-referencing members are updated properly
                Parent::visit( 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
        }

        void Pass2::visit( UnionDecl *unionDecl ) {
                Parent::visit( 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
        }

        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 ( TraitInstType *ctx = dynamic_cast< TraitInstType * >( (*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();
        }

        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() );
                                mutateAll( rtt->get_parameters(), *this );  // recursively fix typedefs on 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;
        }

        template<typename AggDecl>
        void EliminateTypedef::addImplicitTypedef( AggDecl * aggDecl ) {
                if ( typedefNames.count( aggDecl->get_name() ) == 0 ) {
                        Type *type;
                        if ( StructDecl * newDeclStructDecl = dynamic_cast< StructDecl * >( aggDecl ) ) {
                                type = new StructInstType( Type::Qualifiers(), newDeclStructDecl->get_name() );
                        } else if ( UnionDecl * newDeclUnionDecl = dynamic_cast< UnionDecl * >( aggDecl ) ) {
                                type = new UnionInstType( Type::Qualifiers(), newDeclUnionDecl->get_name() );
                        } else if ( EnumDecl * newDeclEnumDecl = dynamic_cast< EnumDecl * >( aggDecl )  ) {
                                type = new EnumInstType( Type::Qualifiers(), newDeclEnumDecl->get_name() );
                        } // if
                        TypedefDecl * tyDecl = new TypedefDecl( aggDecl->get_name(), DeclarationNode::NoStorageClass, type );
                        typedefNames[ aggDecl->get_name() ] = std::make_pair( tyDecl, scopeLevel );
                } // if
        }
        Declaration *EliminateTypedef::mutate( StructDecl * structDecl ) {
                addImplicitTypedef( structDecl );
                Mutator::mutate( structDecl );
                return handleAggregate( structDecl );
        }

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

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

        Declaration *EliminateTypedef::mutate( TraitDecl * 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!
        }

        DeclarationWithType * CompoundLiteral::mutate( ObjectDecl *objectDecl ) {
                storageclass = objectDecl->get_storageClass();
                DeclarationWithType * temp = Mutator::mutate( objectDecl );
                storageclass = DeclarationNode::NoStorageClass;
                return temp;
        }

        Expression *CompoundLiteral::mutate( CompoundLiteralExpr *compLitExpr ) {
                // transform [storage_class] ... (struct S){ 3, ... };
                // into [storage_class] struct S temp =  { 3, ... };
                static UniqueName indexName( "_compLit" );

                ObjectDecl *tempvar = new ObjectDecl( indexName.newName(), storageclass, LinkageSpec::C, 0, compLitExpr->get_type(), compLitExpr->get_initializer() );
                compLitExpr->set_type( 0 );
                compLitExpr->set_initializer( 0 );
                delete compLitExpr;
                DeclarationWithType * newtempvar = mutate( tempvar );
                addDeclaration( newtempvar );                                   // add modified temporary to current block
                return new VariableExpr( newtempvar );
        }
} // namespace SymTab

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// compile-command: "make install" //
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