Changeset aeb75b1 for src/ResolvExpr

Timestamp:

Oct 2, 2017, 3:02:21 PM (7 years ago)

Author:

Aaron Moss <a3moss@…>

Branches:

ADT, aaron-thesis, arm-eh, ast-experimental, cleanup-dtors, deferred_resn, demangler, enum, forall-pointer-decay, jacob/cs343-translation, jenkins-sandbox, master, new-ast, new-ast-unique-expr, new-env, no_list, persistent-indexer, pthread-emulation, qualifiedEnum, resolv-new, with_gc

Children:

e472d54

Parents:

9bae71f

Message:

First draft of iterative bottom-up resolver [BROKEN]

Location:

src/ResolvExpr

Files:

• AlternativeFinder.cc (modified) (6 diffs)
• AlternativeFinder.h (modified) (2 diffs)

src/ResolvExpr/AlternativeFinder.cc

@@ -22 +22 @@
 #include <memory>                  // for allocator_traits<>::value_type
 #include <utility>                 // for pair
+#include <vector>                  // for vector
 
 #include "Alternative.h"           // for AltList, Alternative
@@ -396 +397 @@
 ///     needAssertions.insert( needAssertions.end(), (*tyvar)->get_assertions().begin(), (*tyvar)->get_assertions().end() );
                 }
-        }
-
-        /// instantiate a single argument by matching actuals from [actualIt, actualEnd) against formalType,
-        /// producing expression(s) in out and their total cost in cost.
-        template< typename AltIterator, typename OutputIterator >
-        bool instantiateArgument( Type * formalType, Initializer * defaultValue, AltIterator & actualIt, AltIterator actualEnd, OpenVarSet & openVars, TypeEnvironment & resultEnv, AssertionSet & resultNeed, AssertionSet & resultHave, const SymTab::Indexer & indexer, Cost & cost, OutputIterator out ) {
-                if ( TupleType * tupleType = dynamic_cast< TupleType * >( formalType ) ) {
-                        // formalType is a TupleType - group actuals into a TupleExpr whose type unifies with the TupleType
-                        std::list< Expression * > exprs;
-                        for ( Type * type : *tupleType ) {
-                                if ( ! instantiateArgument( type, defaultValue, actualIt, actualEnd, openVars, resultEnv, resultNeed, resultHave, indexer, cost, back_inserter( exprs ) ) ) {
-                                        deleteAll( exprs );
-                                        return false;
-                                }
-                        }
-                        *out++ = new TupleExpr( exprs );
-                } else if ( TypeInstType * ttype = Tuples::isTtype( formalType ) ) {
-                        // xxx - mixing default arguments with variadic??
-                        std::list< Expression * > exprs;
-                        for ( ; actualIt != actualEnd; ++actualIt ) {
-                                exprs.push_back( actualIt->expr->clone() );
-                                cost += actualIt->cost;
-                        }
-                        Expression * arg = nullptr;
-                        if ( exprs.size() == 1 && Tuples::isTtype( exprs.front()->get_result() ) ) {
-                                // the case where a ttype value is passed directly is special, e.g. for argument forwarding purposes
-                                // xxx - what if passing multiple arguments, last of which is ttype?
-                                // xxx - what would happen if unify was changed so that unifying tuple types flattened both before unifying lists? then pass in TupleType(ttype) below.
-                                arg = exprs.front();
-                        } else {
-                                arg = new TupleExpr( exprs );
-                        }
-                        assert( arg && arg->get_result() );
-                        if ( ! unify( ttype, arg->get_result(), resultEnv, resultNeed, resultHave, openVars, indexer ) ) {
-                                return false;
-                        }
-                        *out++ = arg;
-                } else if ( actualIt != actualEnd ) {
-                        // both actualType and formalType are atomic (non-tuple) types - if they unify
-                        // then accept actual as an argument, otherwise return false (fail to instantiate argument)
-                        Expression * actual = actualIt->expr;
-                        Type * actualType = actual->get_result();
-
-                        PRINT(
-                                std::cerr << "formal type is ";
-                                formalType->print( std::cerr );
-                                std::cerr << std::endl << "actual type is ";
-                                actualType->print( std::cerr );
-                                std::cerr << std::endl;
-                        )
-                        if ( ! unify( formalType, actualType, resultEnv, resultNeed, resultHave, openVars, indexer ) ) {
-                                // std::cerr << "unify failed" << std::endl;
-                                return false;
-                        }
-                        // move the expression from the alternative to the output iterator
-                        *out++ = actual;
-                        actualIt->expr = nullptr;
-                        cost += actualIt->cost;
-                        ++actualIt;
-                } else {
-                        // End of actuals - Handle default values
-                        if ( SingleInit *si = dynamic_cast<SingleInit *>( defaultValue )) {
-                                if ( CastExpr * castExpr = dynamic_cast< CastExpr * >( si->get_value() ) ) {
-                                        // so far, only constant expressions are accepted as default values
-                                        if ( ConstantExpr *cnstexpr = dynamic_cast<ConstantExpr *>( castExpr->get_arg() ) ) {
-                                                if ( Constant *cnst = dynamic_cast<Constant *>( cnstexpr->get_constant() ) ) {
-                                                        if ( unify( formalType, cnst->get_type(), resultEnv, resultNeed, resultHave, openVars, indexer ) ) {
-                                                                *out++ = cnstexpr->clone();
-                                                                return true;
-                                                        } // if
-                                                } // if
-                                        } // if
-                                }
-                        } // if
-                        return false;
-                } // if
-                return true;
-        }
-
-        bool AlternativeFinder::instantiateFunction( std::list< DeclarationWithType* >& formals, const AltList &actuals, bool isVarArgs, OpenVarSet& openVars, TypeEnvironment &resultEnv, AssertionSet &resultNeed, AssertionSet &resultHave, AltList & out ) {
-                simpleCombineEnvironments( actuals.begin(), actuals.end(), resultEnv );
-                // make sure we don't widen any existing bindings
-                for ( TypeEnvironment::iterator i = resultEnv.begin(); i != resultEnv.end(); ++i ) {
-                        i->allowWidening = false;
-                }
-                resultEnv.extractOpenVars( openVars );
-
-                // flatten actuals so that each actual has an atomic (non-tuple) type
-                AltList exploded;
-                Tuples::explode( actuals, indexer, back_inserter( exploded ) );
-
-                AltList::iterator actualExpr = exploded.begin();
-                AltList::iterator actualEnd = exploded.end();
-                for ( DeclarationWithType * formal : formals ) {
-                        // match flattened actuals with formal parameters - actuals will be grouped to match
-                        // with formals as appropriate
-                        Cost cost = Cost::zero;
-                        std::list< Expression * > newExprs;
-                        ObjectDecl * obj = strict_dynamic_cast< ObjectDecl * >( formal );
-                        if ( ! instantiateArgument( obj->get_type(), obj->get_init(), actualExpr, actualEnd, openVars, resultEnv, resultNeed, resultHave, indexer, cost, back_inserter( newExprs ) ) ) {
-                                deleteAll( newExprs );
-                                return false;
-                        }
-                        // success - produce argument as a new alternative
-                        assert( newExprs.size() == 1 );
-                        out.push_back( Alternative( newExprs.front(), resultEnv, cost ) );
-                }
-                if ( actualExpr != actualEnd ) {
-                        // there are still actuals remaining, but we've run out of formal parameters to match against
-                        // this is okay only if the function is variadic
-                        if ( ! isVarArgs ) {
-                                return false;
-                        }
-                        out.splice( out.end(), exploded, actualExpr, actualEnd );
-                }
-                return true;
         }
 
@@ -667 +552 @@
         }
 
-        template< typename OutputIterator >
-        void AlternativeFinder::makeFunctionAlternatives( const Alternative &func, FunctionType *funcType, const AltList &actualAlt, OutputIterator out ) {
-                OpenVarSet openVars;
-                AssertionSet resultNeed, resultHave;
-                TypeEnvironment resultEnv;
-                makeUnifiableVars( funcType, openVars, resultNeed );
-                resultEnv.add( funcType->get_forall() ); // add all type variables as open variables now so that those not used in the parameter list are still considered open
-                AltList instantiatedActuals; // filled by instantiate function
+        /// Gets a default value from an initializer, nullptr if not present
+        ConstantExpr* getDefaultValue( Initializer* init ) {
+                if ( SingleInit* si = dynamic_cast<SingleInit*>( init ) ) {
+                        if ( CastExpr* ce = dynamic_cast<CastExpr*>( si->get_value() ) ) {
+                                return dynamic_cast<ConstantExpr*>( ce->get_arg() );
+                        }
+                }
+                return nullptr;
+        }
+
+        /// State to iteratively build a match of parameter expressions to arguments
+        struct ArgPack {
+                AltList actuals;      ///< Arguments included in this pack
+                TypeEnvironment env;  ///< Environment for this pack
+                AssertionSet need;    ///< Assertions outstanding for this pack
+                AssertionSet have;    ///< Assertions found for this pack
+                OpenVarSet openVars;  ///< Open variables for this pack
+                unsigned nextArg;     ///< Index of next argument in arguments list
+                
+                /// Number of elements included in current tuple element (nested appropriately)
+                std::vector<unsigned> tupleEls;
+
+                ArgPack(const TypeEnvironment& env, const AssertionSet& need, const AssertionSet& have, 
+                                const OpenVarSet& openVars)
+                        : actuals(), env(env), need(need), have(have), openVars(openVars), nextArg(0),
+                          tupleEls() {}
+                
+                ArgPack(const ArgPack& old, Expression* actual, const Cost& cost = Cost::zero)
+                        : actuals(old.actuals), env(old.env), need(old.need), have(old.have), 
+                          openVars(old.openVars), nextArg(old.nextArg + 1), tupleEls(old.tupleEls) {
+                        actuals.emplace_back( actual, this->env, cost );
+                }
+                
+                ArgPack(const ArgPack& old, Expression* actual, TypeEnvironment&& env, AssertionSet&& need, 
+                                AssertionSet&& have, const Cost& cost = Cost::zero)
+                        : actuals(old.actuals), env(std::move(env)), need(std::move(need)), 
+                          have(std::move(have)), openVars(old.openVars), nextArg(old.nextArg + 1), 
+                          tupleEls(old.tupleEls) {
+                        // add new actual
+                        actuals.emplace_back( actual, this->env, cost );
+                        // count tuple elements, if applicable
+                        if ( ! tupleEls.empty() ) ++tupleEls.back();
+                }
+
+                /// Starts a new tuple expression
+                void beginTuple() {
+                        if ( ! tupleEls.empty() ) ++tupleEls.back();
+                        tupleEls.push_back(0);
+                }
+
+                /// Ends a tuple expression, consolidating the appropriate actuals
+                void endTuple() {
+                        // set up new Tuple alternative
+                        std::list<Expression*> exprs;
+                        Cost cost = Cost::zero;
+
+                        // transfer elements into alternative
+                        for (unsigned i = 0; i < tupleEls.back(); ++i) {
+                                exprs.push_front( actuals.back().expr );
+                                cost += actuals.back().cost;
+                                actuals.pop_back();
+                        }
+                        tupleEls.pop_back();
+
+                        // build new alternative
+                        actuals.emplace_back( new TupleExpr( exprs ), this->env, cost );
+                }
+        };
+
+        /// Iterates a result, exploding actuals as needed.
+        /// add is a function that takes the same parameters as this (with the exception of add)
+        template<typename F>
+        void addExplodedActual( ArgPack& result, Expression* expr, Cost cost, 
+                        std::vector<ArgPack>& nextResults, F add ) {
+                Type* res = expr->get_result()->stripReferences();
+                if ( TupleType* tupleType = dynamic_cast<TupleType*>( res ) ) {
+                        if ( TupleExpr* tupleExpr = dynamic_cast<TupleExpr*>( expr ) ) {
+                                // recursively explode tuple
+                                for ( Expression* sexpr : tupleExpr->get_exprs() ) {
+                                        addExplodedActual( result, sexpr, cost, nextResults, add );
+                                        cost = Cost::zero; // reset cost so not duplicated
+                                }
+                        } else {
+                                // tuple type, but not tuple expr - recursively index into components.
+                                // if expr type is reference, convert to value type
+                                Expression* arg = expr->clone();
+                                if ( Tuples::maybeImpureIgnoreUnique( arg ) ) {
+                                        // expressions which may contain side effects require a single unique instance of the expression.
+                                        arg = new UniqueExpr( arg );
+                                }
+                                // cast reference to value type to facilitate further explosion
+                                if ( dynamic_cast<ReferenceType*>( arg->get_result() ) ) {
+                                        arg = new CastExpr( arg, tupleType->clone() );
+                                }
+                                // explode tuple by index
+                                for ( unsigned i = 0; i < tupleType->size(); ++i ) {
+                                        TupleIndexExpr* idx = new TupleIndexExpr( arg->clone(), i );
+                                        addExplodedActual( result, idx, cost, nextResults, add );
+                                        cost = Cost::zero; // reset cost so not duplicated
+                                        delete idx;
+                                }
+                                delete arg;
+                        }
+                } else {
+                        // add non-tuple results directly
+                        add( result, expr->clone(), cost, nextResults );
+                }
+        }
+
+        /// Instantiates an argument to match a formal, returns false if no results left
+        bool instantiateArgument( Type* formalType, Initializer* initializer, 
+                        const std::vector< AlternativeFinder >& args, 
+                        std::vector<ArgPack>& results, std::vector<ArgPack>& nextResults, 
+                        const SymTab::Indexer& indexer ) {
+                if ( TupleType* tupleType = dynamic_cast<TupleType*>( formalType ) ) {
+                        // formalType is a TupleType - group actuals into a TupleExpr
+                        for ( ArgPack& result : results ) { result.beginTuple(); }
+                        for ( Type* type : *tupleType ) {
+                                // xxx - dropping initializer changes behaviour from previous, but seems correct
+                                if ( ! instantiateArgument( type, nullptr, args, results, nextResults, indexer ) ) 
+                                        return false;
+                        }
+                        for ( ArgPack& result : results ) { result.endTuple(); }
+                        return true;
+                } else if ( TypeInstType* ttype = Tuples::isTtype( formalType ) ) {
+                        // formalType is a ttype, consumes all remaining arguments
+                        // xxx - mixing default arguments with variadic??
+                        std::vector<ArgPack> finalResults{};  /// list of completed tuples
+                        // start tuples
+                        for ( ArgPack& result : results ) { result.beginTuple(); }
+                        // iterate until all results completed
+                        while ( ! results.empty() ) {
+                                // add another argument to results
+                                for ( ArgPack& result : results ) {
+                                        // finish result when out of arguments
+                                        if ( result.nextArg >= args.size() ) {
+                                                Type* argType = result.actuals.back().expr->get_result();
+                                                if ( result.tupleEls.back() == 1 && Tuples::isTtype( argType ) ) {
+                                                        // the case where a ttype value is passed directly is special, e.g. for 
+                                                        // argument forwarding purposes
+                                                        // xxx - what if passing multiple arguments, last of which is ttype?
+                                                        // xxx - what would happen if unify was changed so that unifying tuple 
+                                                        // types flattened both before unifying lists? then pass in TupleType
+                                                        // (ttype) below.
+                                                        result.tupleEls.pop_back();
+                                                } else {
+                                                        // collapse leftover arguments into tuple
+                                                        result.endTuple();
+                                                        argType = result.actuals.back().expr->get_result();
+                                                }
+                                                // check unification for ttype before adding to final
+                                                if ( unify( ttype, argType, result.env, result.need, result.have, 
+                                                                result.openVars, indexer ) ) {
+                                                        finalResults.emplace_back( std::move(result) );
+                                                }
+                                                continue;
+                                        }
+
+                                        // add each possible next argument
+                                        for ( const Alternative& actual : args[result.nextArg] ) {
+                                                addExplodedActual( result, actual.expr, actual.cost, nextResults, 
+                                                        []( ArgPack& result, Expression* expr, Cost cost, 
+                                                                        std::vector<ArgPack>& nextResults ) {
+                                                                nextResults.emplace_back( result, expr, cost );
+                                                        } );
+                                        }
+                                }
+
+                                // reset for next round
+                                results.swap( nextResults );
+                                nextResults.clear();
+                        }
+                        results.swap( finalResults );
+                        return ! results.empty();
+                }
+                
+                // iterate each current subresult
+                for ( ArgPack& result : results ) {
+                        if ( result.nextArg >= args.size() ) {
+                                // If run out of actuals, handle default values
+                                if ( ConstantExpr* cnstExpr = getDefaultValue( initializer ) ) {
+                                        if ( Constant* cnst = dynamic_cast<Constant*>( cnstExpr->get_constant() ) ) {
+                                                TypeEnvironment resultEnv = result.env;
+                                                AssertionSet resultNeed = result.need, resultHave = result.have;
+                                                if ( unify( formalType, cnst->get_type(), 
+                                                                resultEnv, resultNeed, resultHave, result.openVars, 
+                                                                indexer ) ) {
+                                                        nextResults.emplace_back( result, cnstExpr->clone(), 
+                                                                std::move(resultEnv), std::move(resultNeed), 
+                                                                std::move(resultHave) );
+                                                }
+                                        }
+                                }
+                                continue;
+                        }
+
+                        // Check each possible next argument
+                        for ( const Alternative& actual : args[result.nextArg] ) {
+                                addExplodedActual( result, actual.expr, actual.cost, nextResults, 
+                                        [formalType,&indexer]( ArgPack& result, Expression* expr, Cost cost, 
+                                                        std::vector<ArgPack>& nextResults ) {
+                                                // attempt to unify actual with parameter
+                                                TypeEnvironment resultEnv = result.env;
+                                                AssertionSet resultNeed = result.need, resultHave = result.have;
+                                                Type* actualType = expr->get_result();
+
+                                                PRINT(
+                                                        std::cerr << "formal type is ";
+                                                        formalType->print( std::cerr );
+                                                        std::cerr << std::endl << "actual type is ";
+                                                        actualType->print( std::cerr );
+                                                        std::cerr << std::endl;
+                                                )
+
+                                                if ( unify( formalType, actualType, resultEnv, resultNeed, resultHave, 
+                                                                result.openVars, indexer ) ) {
+                                                        nextResults.emplace_back( result, expr->clone(), 
+                                                                std::move(resultEnv), std::move(resultNeed), std::move(resultHave),
+                                                                cost );
+                                                }
+                                        } );
+                        }
+                }
+
+                // reset for next parameter
+                results.swap( nextResults );
+                nextResults.clear();
+                
+                return ! results.empty();
+        }
+
+        template<typename OutputIterator>
+        void AlternativeFinder::makeFunctionAlternatives( const Alternative& func, 
+                        FunctionType* funcType, const std::vector< AlternativeFinder >& args, 
+                        OutputIterator out ) {
+                OpenVarSet funcOpenVars;
+                AssertionSet funcNeed, funcHave;
+                TypeEnvironment funcEnv;
+                makeUnifiableVars( funcType, funcOpenVars, funcNeed );
+                // add all type variables as open variables now so that those not used in the parameter 
+                // list are still considered open.
+                funcEnv.add( funcType->get_forall() );
+
                 if ( targetType && ! targetType->isVoid() && ! funcType->get_returnVals().empty() ) {
                         // attempt to narrow based on expected target type
-                        Type * returnType = funcType->get_returnVals().front()->get_type();
-                        if ( ! unify( returnType, targetType, resultEnv, resultNeed, resultHave, openVars, indexer ) ) {
-                                // unification failed, don't pursue this alternative
+                        Type* returnType = funcType->get_returnVals().front()->get_type();
+                        if ( ! unify( returnType, targetType, funcEnv, funcNeed, funcHave, funcOpenVars, 
+                                        indexer ) ) {
+                                // unification failed, don't pursue this function alternative
                                 return;
                         }
                 }
 
-                if ( instantiateFunction( funcType->get_parameters(), actualAlt, funcType->get_isVarArgs(), openVars, resultEnv, resultNeed, resultHave, instantiatedActuals ) ) {
+                // iteratively build matches, one parameter at a time
+                std::vector<ArgPack> results{ ArgPack{ funcEnv, funcNeed, funcHave, funcOpenVars } };
+                std::vector<ArgPack> nextResults{};
+                for ( DeclarationWithType* formal : funcType->get_parameters() ) {
+                        ObjectDecl* obj = strict_dynamic_cast< ObjectDecl* >( formal );
+                        if ( ! instantiateArgument( 
+                                        obj->get_type(), obj->get_init(), args, results, nextResults, indexer ) )
+                                return;
+                }
+
+                // filter out results that don't use all the arguments, and aren't variadic
+                std::vector<ArgPack> finalResults{};
+                if ( funcType->get_isVarArgs() ) {
+                        while ( ! results.empty() ) {
+                                // build combinations for all remaining arguments
+                                for ( ArgPack& result : results ) {
+                                        // keep if used all arguments
+                                        if ( result.nextArg >= args.size() ) {
+                                                finalResults.emplace_back( std::move(result) );
+                                                continue;
+                                        }
+
+                                        // add each possible next argument
+                                        for ( const Alternative& actual : args[result.nextArg] ) {
+                                                nextResults.emplace_back( result, actual.expr, actual.cost );
+                                        }
+                                }
+
+                                // reset for next round
+                                results.swap( nextResults );
+                                nextResults.clear();
+                        }
+                } else {
+                        // filter out results that don't use all the arguments
+                        for ( ArgPack& result : results ) {
+                                if ( result.nextArg >= args.size() ) {
+                                        finalResults.emplace_back( std::move(result) );
+                                }
+                        }
+                }
+
+                // validate matching combos, add to final result list
+                for ( ArgPack& result : finalResults ) {
                         ApplicationExpr *appExpr = new ApplicationExpr( func.expr->clone() );
-                        Alternative newAlt( appExpr, resultEnv, sumCost( instantiatedActuals ) );
-                        makeExprList( instantiatedActuals, appExpr->get_args() );
+                        Alternative newAlt( appExpr, result.env, sumCost( result.actuals ) );
+                        makeExprList( result.actuals, appExpr->get_args() );
                         PRINT(
                                 std::cerr << "instantiate function success: " << appExpr << std::endl;
                                 std::cerr << "need assertions:" << std::endl;
-                                printAssertionSet( resultNeed, std::cerr, 8 );
+                                printAssertionSet( result.need, std::cerr, 8 );
                         )
-                        inferParameters( resultNeed, resultHave, newAlt, openVars, out );
+                        inferParameters( result.need, result.have, newAlt, result.openVars, out );
                 }
         }
@@ -703 +866 @@
                 if ( funcFinder.alternatives.empty() ) return;
 
-                std::list< AlternativeFinder > argAlternatives;
-                findSubExprs( untypedExpr->begin_args(), untypedExpr->end_args(), back_inserter( argAlternatives ) );
-
-                std::list< AltList > possibilities;
-                combos( argAlternatives.begin(), argAlternatives.end(), back_inserter( possibilities ) );
+                std::vector< AlternativeFinder > argAlternatives;
+                findSubExprs( untypedExpr->begin_args(), untypedExpr->end_args(), 
+                        back_inserter( argAlternatives ) );
 
                 // take care of possible tuple assignments
                 // if not tuple assignment, assignment is taken care of as a normal function call
-                Tuples::handleTupleAssignment( *this, untypedExpr, possibilities );
-
+/*FIX   Tuples::handleTupleAssignment( *this, untypedExpr, possibilities );
+*/
                 // find function operators
                 AlternativeFinder funcOpFinder( indexer, env );
@@ -739 +900 @@
                                                 Alternative newFunc( *func );
                                                 referenceToRvalueConversion( newFunc.expr );
-                                                for ( std::list< AltList >::iterator actualAlt = possibilities.begin(); actualAlt != possibilities.end(); ++actualAlt ) {
-                                                        // XXX
-                                                        //Designators::check_alternative( function, *actualAlt );
-                                                        makeFunctionAlternatives( newFunc, function, *actualAlt, std::back_inserter( candidates ) );
-                                                }
+                                                makeFunctionAlternatives( newFunc, function, argAlternatives, 
+                                                        std::back_inserter( candidates ) );
                                         }
                                 } else if ( TypeInstType *typeInst = dynamic_cast< TypeInstType* >( func->expr->get_result()->stripReferences() ) ) { // handle ftype (e.g. *? on function pointer)
@@ -751 +909 @@
                                                         Alternative newFunc( *func );
                                                         referenceToRvalueConversion( newFunc.expr );
-                                                        for ( std::list< AltList >::iterator actualAlt = possibilities.begin(); actualAlt != possibilities.end(); ++actualAlt ) {
-                                                                makeFunctionAlternatives( newFunc, function, *actualAlt, std::back_inserter( candidates ) );
-                                                        } // for
+                                                        makeFunctionAlternatives( newFunc, function, argAlternatives, 
+                                                                std::back_inserter( candidates ) );
                                                 } // if
                                         } // if
-                                }
-
-                                // try each function operator ?() with the current function alternative and each of the argument combinations
-                                for ( AltList::iterator funcOp = funcOpFinder.alternatives.begin(); funcOp != funcOpFinder.alternatives.end(); ++funcOp ) {
-                                        // check if the type is pointer to function
-                                        if ( PointerType *pointer = dynamic_cast< PointerType* >( funcOp->expr->get_result()->stripReferences() ) ) {
-                                                if ( FunctionType *function = dynamic_cast< FunctionType* >( pointer->get_base() ) ) {
+                                }                       
+                        } catch ( SemanticError &e ) {
+                                errors.append( e );
+                        }
+                } // for
+
+                // try each function operator ?() with each function alternative
+                if ( ! funcOpFinder.alternatives.empty() ) {
+                        // add function alternatives to front of argument list
+                        argAlternatives.insert( argAlternatives.begin(), std::move(funcFinder) );
+
+                        for ( AltList::iterator funcOp = funcOpFinder.alternatives.begin();
+                                        funcOp != funcOpFinder.alternatives.end(); ++funcOp ) {
+                                try {
+                                        // check if type is a pointer to function
+                                        if ( PointerType* pointer = dynamic_cast<PointerType*>( 
+                                                        funcOp->expr->get_result()->stripReferences() ) ) {
+                                                if ( FunctionType* function = 
+                                                                dynamic_cast<FunctionType*>( pointer->get_base() ) ) {
                                                         Alternative newFunc( *funcOp );
                                                         referenceToRvalueConversion( newFunc.expr );
-                                                        for ( std::list< AltList >::iterator actualAlt = possibilities.begin(); actualAlt != possibilities.end(); ++actualAlt ) {
-                                                                AltList currentAlt;
-                                                                currentAlt.push_back( *func );
-                                                                currentAlt.insert( currentAlt.end(), actualAlt->begin(), actualAlt->end() );
-                                                                makeFunctionAlternatives( newFunc, function, currentAlt, std::back_inserter( candidates ) );
-                                                        } // for
-                                                } // if
-                                        } // if
-                                } // for
-                        } catch ( SemanticError &e ) {
-                                errors.append( e );
-                        }
-                } // for
+                                                        makeFunctionAlternatives( newFunc, function, argAlternatives, 
+                                                                std::back_inserter( candidates ) );
+                                                }
+                                        }
+                                } catch ( SemanticError &e ) {
+                                        errors.append( e );
+                                }
+                        }
+                }
 
                 // Implement SFINAE; resolution errors are only errors if there aren't any non-erroneous resolutions

src/ResolvExpr/AlternativeFinder.h

@@ -34 +34 @@
           public:
                 AlternativeFinder( const SymTab::Indexer &indexer, const TypeEnvironment &env );
+
+                AlternativeFinder( const AlternativeFinder& o )
+                        : indexer(o.indexer), alternatives(o.alternatives), env(o.env), 
+                          targetType(o.targetType) {}
+                
+                AlternativeFinder( AlternativeFinder&& o )
+                        : indexer(o.indexer), alternatives(std::move(o.alternatives)), env(o.env), 
+                          targetType(o.targetType) {}
+                
+                AlternativeFinder& operator= ( const AlternativeFinder& o ) {
+                        if (&o == this) return *this;
+                        
+                        // horrific nasty hack to rebind references...
+                        alternatives.~AltList();
+                        new(this) AlternativeFinder(o);
+                        return *this;
+                }
+
+                AlternativeFinder& operator= ( AlternativeFinder&& o ) {
+                        if (&o == this) return *this;
+                        
+                        // horrific nasty hack to rebind references...
+                        alternatives.~AltList();
+                        new(this) AlternativeFinder(std::move(o));
+                        return *this;
+                }
+
                 void find( Expression *expr, bool adjust = false, bool prune = true );
                 /// Calls find with the adjust flag set; adjustment turns array and function types into equivalent pointer types
@@ -94 +121 @@
                 /// Adds alternatives for offsetof expressions, given the base type and name of the member
                 template< typename StructOrUnionType > void addOffsetof( StructOrUnionType *aggInst, const std::string &name );
-                bool instantiateFunction( std::list< DeclarationWithType* >& formals, const AltList &actuals, bool isVarArgs, OpenVarSet& openVars, TypeEnvironment &resultEnv, AssertionSet &resultNeed, AssertionSet &resultHave, AltList & out );
+/*CUT   bool instantiateFunction( std::list< DeclarationWithType* >& formals, const AltList &actuals, bool isVarArgs, OpenVarSet& openVars, TypeEnvironment &resultEnv, AssertionSet &resultNeed, AssertionSet &resultHave, AltList & out );
                 template< typename OutputIterator >
                 void makeFunctionAlternatives( const Alternative &func, FunctionType *funcType, const AltList &actualAlt, OutputIterator out );
+*/              template<typename OutputIterator>
+                void makeFunctionAlternatives( const Alternative &func, FunctionType *funcType, const std::vector< AlternativeFinder >& args, OutputIterator out );
                 template< typename OutputIterator >
                 void inferParameters( const AssertionSet &need, AssertionSet &have, const Alternative &newAlt, OpenVarSet &openVars, OutputIterator out );