Changeset c71b256

Timestamp:

Feb 16, 2018, 4:14:29 PM (6 years ago)

Author:

Rob Schluntz <rschlunt@…>

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:

7c782af

Parents:

4a161be

Message:

Add resolver error when a deleted identifier is in the final lowest cost interpretation, refactor top-level resolver functions

Location:

src/ResolvExpr

Files:

• AlternativeFinder.cc (modified) (3 diffs)
• Resolver.cc (modified) (6 diffs)

src/ResolvExpr/AlternativeFinder.cc

@@ -95 +95 @@
                 void postvisit( StmtExpr * stmtExpr );
                 void postvisit( UntypedInitExpr * initExpr );
+                void postvisit( InitExpr * initExpr );
+                void postvisit( DeletedExpr * delExpr );
 
                 /// Adds alternatives for anonymous members
@@ -120 +122 @@
                 Type *& targetType;
         };
-
-        Expression *resolveInVoidContext( Expression *expr, const SymTab::Indexer &indexer, TypeEnvironment &env ) {
-                CastExpr *castToVoid = new CastExpr( expr );
-
-                AlternativeFinder finder( indexer, env );
-                finder.findWithAdjustment( castToVoid );
-
-                // it's a property of the language that a cast expression has either 1 or 0 interpretations; if it has 0
-                // interpretations, an exception has already been thrown.
-                assert( finder.get_alternatives().size() == 1 );
-                CastExpr *newExpr = dynamic_cast< CastExpr* >( finder.get_alternatives().front().expr );
-                assert( newExpr );
-                env = finder.get_alternatives().front().env;
-                return newExpr->get_arg()->clone();
-        }
 
         Cost sumCost( const AltList &in ) {
@@ -1751 +1738 @@
                 findMinCost( minArgCost.begin(), minArgCost.end(), std::back_inserter( alternatives ) );
         }
+
+        void AlternativeFinder::Finder::postvisit( InitExpr * ) {
+                assertf( false, "AlternativeFinder should never see a resolved InitExpr." );
+        }
+
+        void AlternativeFinder::Finder::postvisit( DeletedExpr * ) {
+                assertf( false, "AlternativeFinder should never see a DeletedExpr." );
+        }
 } // namespace ResolvExpr
 

src/ResolvExpr/Resolver.cc

@@ -105 +105 @@
         }
 
-        // used in resolveTypeof
-        Expression *resolveInVoidContext( Expression *expr, const SymTab::Indexer &indexer ) {
-                TypeEnvironment env;
-                return resolveInVoidContext( expr, indexer, env );
+        namespace {
+                struct DeleteFinder : public WithShortCircuiting        {
+                        DeletedExpr * delExpr = nullptr;
+                        void previsit( DeletedExpr * expr ) {
+                                if ( delExpr ) visit_children = false;
+                                else delExpr = expr;
+                        }
+
+                        void previsit( Expression * ) {
+                                if ( delExpr ) visit_children = false;
+                        }
+                };
+        }
+
+        DeletedExpr * findDeletedExpr( Expression * expr ) {
+                PassVisitor<DeleteFinder> finder;
+                expr->accept( finder );
+                return finder.pass.delExpr;
         }
 
@@ -130 +144 @@
         } // namespace
 
+        namespace {
+                void findUnfinishedKindExpression(Expression * untyped, Alternative & alt, const SymTab::Indexer & indexer, const std::string & kindStr, std::function<bool(const Alternative &)> pred, bool adjust = false, bool prune = true, bool failFast = true) {
+                        assertf( untyped, "expected a non-null expression." );
+                        TypeEnvironment env;
+                        AlternativeFinder finder( indexer, env );
+                        finder.find( untyped, adjust, prune, failFast );
+
+                        #if 0
+                        if ( finder.get_alternatives().size() != 1 ) {
+                                std::cerr << "untyped expr is ";
+                                untyped->print( std::cerr );
+                                std::cerr << std::endl << "alternatives are:";
+                                for ( const Alternative & alt : finder.get_alternatives() ) {
+                                        alt.print( std::cerr );
+                                } // for
+                        } // if
+                        #endif
+
+                        AltList candidates;
+                        for ( Alternative & alt : finder.get_alternatives() ) {
+                                if ( pred( alt ) ) {
+                                        candidates.push_back( std::move( alt ) );
+                                }
+                        }
+
+                        // xxx - if > 1 alternative with same cost, ignore deleted and pick from remaining
+                        // choose the lowest cost expression among the candidates
+                        AltList winners;
+                        findMinCost( candidates.begin(), candidates.end(), back_inserter( winners ) );
+                        if ( winners.size() == 0 ) {
+                                throw SemanticError( toString( "No reasonable alternatives for ", kindStr, (kindStr != "" ? " " : ""), "expression: "), untyped );
+                        } else if ( winners.size() != 1 ) {
+                                std::ostringstream stream;
+                                stream << "Cannot choose between " << winners.size() << " alternatives for " << kindStr << (kindStr != "" ? " " : "") << "expression\n";
+                                untyped->print( stream );
+                                stream << "Alternatives are:\n";
+                                printAlts( winners, stream, 1 );
+                                throw SemanticError( stream.str() );
+                        }
+
+                        // there is one unambiguous interpretation - move the expression into the with statement
+                        Alternative & choice = winners.front();
+                        if ( findDeletedExpr( choice.expr ) ) {
+                                throw SemanticError( "Unique best alternative includes deleted identifier in ", choice.expr );
+                        }
+                        alt = std::move( choice );
+                }
+
+                /// resolve `untyped` to the expression whose alternative satisfies `pred` with the lowest cost; kindStr is used for providing better error messages
+                void findKindExpression(Expression *& untyped, const SymTab::Indexer & indexer, const std::string & kindStr, std::function<bool(const Alternative &)> pred, bool adjust = false, bool prune = true, bool failFast = true) {
+                        if ( ! untyped ) return;
+                        Alternative choice;
+                        findUnfinishedKindExpression( untyped, choice, indexer, kindStr, pred, adjust, prune, failFast );
+                        finishExpr( choice.expr, choice.env, untyped->env );
+                        delete untyped;
+                        untyped = choice.expr;
+                        choice.expr = nullptr;
+                }
+
+                bool standardAlternativeFilter( const Alternative & ) {
+                        // currently don't need to filter, under normal circumstances.
+                        // in the future, this may be useful for removing deleted expressions
+                        return true;
+                }
+        } // namespace
+
+        // used in resolveTypeof
+        Expression * resolveInVoidContext( Expression *expr, const SymTab::Indexer &indexer ) {
+                TypeEnvironment env;
+                return resolveInVoidContext( expr, indexer, env );
+        }
+
+        Expression * resolveInVoidContext( Expression *expr, const SymTab::Indexer &indexer, TypeEnvironment &env ) {
+                // it's a property of the language that a cast expression has either 1 or 0 interpretations; if it has 0
+                // interpretations, an exception has already been thrown.
+                assertf( expr, "expected a non-null expression." );
+
+                static CastExpr untyped( nullptr ); // cast to void
+
+                // set up and resolve expression cast to void
+                untyped.arg = expr;
+                Alternative choice;
+                findUnfinishedKindExpression( &untyped, choice, indexer, "", standardAlternativeFilter, true );
+                CastExpr * castExpr = strict_dynamic_cast< CastExpr * >( choice.expr );
+                env = std::move( choice.env );
+
+                // clean up resolved expression
+                Expression * ret = castExpr->arg;
+                castExpr->arg = nullptr;
+
+                // unlink the arg so that it isn't deleted twice at the end of the program
+                untyped.arg = nullptr;
+                return ret;
+        }
+
         void findVoidExpression( Expression *& untyped, const SymTab::Indexer &indexer ) {
                 resetTyVarRenaming();
                 TypeEnvironment env;
-                Expression *newExpr = resolveInVoidContext( untyped, indexer, env );
+                Expression * newExpr = resolveInVoidContext( untyped, indexer, env );
                 finishExpr( newExpr, env, untyped->env );
                 delete untyped;
@@ -140 +249 @@
 
         void findSingleExpression( Expression *&untyped, const SymTab::Indexer &indexer ) {
-                if ( ! untyped ) return;
-                TypeEnvironment env;
-                AlternativeFinder finder( indexer, env );
-                finder.find( untyped );
-                #if 0
-                if ( finder.get_alternatives().size() != 1 ) {
-                        std::cerr << "untyped expr is ";
-                        untyped->print( std::cerr );
-                        std::cerr << std::endl << "alternatives are:";
-                        for ( const Alternative & alt : finder.get_alternatives() ) {
-                                alt.print( std::cerr );
-                        } // for
-                } // if
-                #endif
-                assertf( finder.get_alternatives().size() == 1, "findSingleExpression: must have exactly one alternative at the end: (%zd) %s", finder.get_alternatives().size(), toString( untyped ).c_str() );
-                Alternative &choice = finder.get_alternatives().front();
-                Expression *newExpr = choice.expr->clone();
-                finishExpr( newExpr, choice.env, untyped->env );
-                delete untyped;
-                untyped = newExpr;
+                findKindExpression( untyped, indexer, "", standardAlternativeFilter );
         }
 
@@ -170 +260 @@
 
         namespace {
-                /// resolve `untyped` to the expression whose type satisfies `pred` with the lowest cost; kindStr is used for providing better error messages
-                template<typename Pred>
-                void findKindExpression(Expression *& untyped, const SymTab::Indexer & indexer, const std::string & kindStr, Pred pred) {
-                        TypeEnvironment env;
-                        AlternativeFinder finder( indexer, env );
-                        finder.findWithAdjustment( untyped );
-
-                        AltList candidates;
-                        for ( Alternative & alt : finder.get_alternatives() ) {
-                                if ( pred( alt.expr->result ) ) {
-                                        candidates.push_back( std::move( alt ) );
-                                }
-                        }
-
-                        // choose the lowest cost expression among the candidates
-                        AltList winners;
-                        findMinCost( candidates.begin(), candidates.end(), back_inserter( winners ) );
-                        if ( winners.size() == 0 ) {
-                                throw SemanticError( "No reasonable alternatives for " + kindStr + " expression: ", untyped );
-                        } else if ( winners.size() != 1 ) {
-                                std::ostringstream stream;
-                                stream << "Cannot choose between " << winners.size() << " alternatives for " + kindStr +  " expression\n";
-                                untyped->print( stream );
-                                stream << "Alternatives are:\n";
-                                printAlts( winners, stream, 1 );
-                                throw SemanticError( stream.str() );
-                        }
-
-                        // there is one unambiguous interpretation - move the expression into the with statement
-                        Alternative & alt = winners.front();
-                        finishExpr( alt.expr, alt.env, untyped->env );
-                        delete untyped;
-                        untyped = alt.expr;
-                        alt.expr = nullptr;
-                }
-
-                bool isIntegralType( Type *type ) {
+                bool isIntegralType( const Alternative & alt ) {
+                        Type * type = alt.expr->result;
                         if ( dynamic_cast< EnumInstType * >( type ) ) {
                                 return true;
@@ -559 +614 @@
                         if( func_candidates.size() > 1 ) { SemanticError top( "Ambiguous function in call to waitfor"            ); top.append( errors ); throw top; }
                         if( args_candidates.size() > 1 ) { SemanticError top( "Ambiguous arguments in call to waitfor"           ); top.append( errors ); throw top; }
-
+                        // TODO: need to use findDeletedExpr to ensure no deleted identifiers are used.
 
                         // Swap the results from the alternative with the unresolved values.
@@ -592 +647 @@
         }
 
-        bool isStructOrUnion( Type * t ) {
-                t = t->stripReferences();
+        bool isStructOrUnion( const Alternative & alt ) {
+                Type * t = alt.expr->result->stripReferences();
                 return dynamic_cast< StructInstType * >( t ) || dynamic_cast< UnionInstType * >( t );
         }