[FOLD] store all results found by unqualified lookup for the first component name of a member-qualified nested-name-specifier

Author: sdkrystian

clang/include/clang/AST/ExprCXX.h

@@ -3672,8 +3672,10 @@ class CXXUnresolvedConstructExpr final
 class CXXDependentScopeMemberExpr final
     : public Expr,
       private llvm::TrailingObjects<CXXDependentScopeMemberExpr,
+                                    NestedNameSpecifierLoc,
+                                    DeclAccessPair,
                                     ASTTemplateKWAndArgsInfo,
-                                    TemplateArgumentLoc, NamedDecl *> {
+                                    TemplateArgumentLoc> {
   friend class ASTStmtReader;
   friend class ASTStmtWriter;
   friend TrailingObjects;
@@ -3686,17 +3688,15 @@ class CXXDependentScopeMemberExpr final
   /// implicit accesses.
   QualType BaseType;
 
-  /// The nested-name-specifier that precedes the member name, if any.
-  /// FIXME: This could be in principle store as a trailing object.
-  /// However the performance impact of doing so should be investigated first.
-  NestedNameSpecifierLoc QualifierLoc;
-
   /// The member to which this member expression refers, which
   /// can be name, overloaded operator, or destructor.
   ///
   /// FIXME: could also be a template-id
   DeclarationNameInfo MemberNameInfo;
 
+  /// The location of the '->' or '.' operator.
+  SourceLocation OperatorLoc;
+
   // CXXDependentScopeMemberExpr is followed by several trailing objects,
   // some of which optional. They are in order:
   //
@@ -3716,8 +3716,16 @@ class CXXDependentScopeMemberExpr final
     return CXXDependentScopeMemberExprBits.HasTemplateKWAndArgsInfo;
   }
 
-  bool hasFirstQualifierFoundInScope() const {
-    return CXXDependentScopeMemberExprBits.HasFirstQualifierFoundInScope;
+  unsigned getNumUnqualifiedLookups() const {
+    return CXXDependentScopeMemberExprBits.NumUnqualifiedLookups;
+  }
+
+  unsigned numTrailingObjects(OverloadToken<NestedNameSpecifierLoc>) const {
+    return hasQualifier();
+  }
+
+  unsigned numTrailingObjects(OverloadToken<DeclAccessPair>) const {
+    return getNumUnqualifiedLookups();
   }
 
   unsigned numTrailingObjects(OverloadToken<ASTTemplateKWAndArgsInfo>) const {
@@ -3728,33 +3736,35 @@ class CXXDependentScopeMemberExpr final
     return getNumTemplateArgs();
   }
 
-  unsigned numTrailingObjects(OverloadToken<NamedDecl *>) const {
-    return hasFirstQualifierFoundInScope();
-  }
-
   CXXDependentScopeMemberExpr(const ASTContext &Ctx, Expr *Base,
                               QualType BaseType, bool IsArrow,
                               SourceLocation OperatorLoc,
                               NestedNameSpecifierLoc QualifierLoc,
                               SourceLocation TemplateKWLoc,
-                              NamedDecl *FirstQualifierFoundInScope,
+                              ArrayRef<DeclAccessPair> UnqualifiedLookups,
                               DeclarationNameInfo MemberNameInfo,
                               const TemplateArgumentListInfo *TemplateArgs);
 
-  CXXDependentScopeMemberExpr(EmptyShell Empty, bool HasTemplateKWAndArgsInfo,
-                              bool HasFirstQualifierFoundInScope);
+  CXXDependentScopeMemberExpr(EmptyShell Empty, bool HasQualifier,
+                              unsigned NumUnqualifiedLookups,
+                              bool HasTemplateKWAndArgsInfo);
 
 public:
   static CXXDependentScopeMemberExpr *
-  Create(const ASTContext &Ctx, Expr *Base, QualType BaseType, bool IsArrow,
-         SourceLocation OperatorLoc, NestedNameSpecifierLoc QualifierLoc,
-         SourceLocation TemplateKWLoc, NamedDecl *FirstQualifierFoundInScope,
+  Create(const ASTContext &Ctx, Expr *Base,
+         QualType BaseType, bool IsArrow,
+         SourceLocation OperatorLoc,
+         NestedNameSpecifierLoc QualifierLoc,
+         SourceLocation TemplateKWLoc,
+         ArrayRef<DeclAccessPair> UnqualifiedLookups,
          DeclarationNameInfo MemberNameInfo,
          const TemplateArgumentListInfo *TemplateArgs);
 
   static CXXDependentScopeMemberExpr *
-  CreateEmpty(const ASTContext &Ctx, bool HasTemplateKWAndArgsInfo,
-              unsigned NumTemplateArgs, bool HasFirstQualifierFoundInScope);
+  CreateEmpty(const ASTContext &Ctx, bool HasQualifier,
+              unsigned NumUnqualifiedLookups,
+              bool HasTemplateKWAndArgsInfo,
+              unsigned NumTemplateArgs);
 
   /// True if this is an implicit access, i.e. one in which the
   /// member being accessed was not written in the source.  The source
@@ -3780,18 +3790,32 @@ class CXXDependentScopeMemberExpr final
 
   /// Retrieve the location of the '->' or '.' operator.
   SourceLocation getOperatorLoc() const {
-    return CXXDependentScopeMemberExprBits.OperatorLoc;
+    return OperatorLoc;
+  }
+
+  /// Determines whether this member expression had a nested-name-specifier
+  /// prior to the name of the member, e.g., x->Base::foo.
+  bool hasQualifier() const {
+    return CXXDependentScopeMemberExprBits.HasQualifier;
   }
 
-  /// Retrieve the nested-name-specifier that qualifies the member name.
+  /// If the member name was qualified, retrieves the nested-name-specifier
+  /// that precedes the member name, with source-location information.
+  NestedNameSpecifierLoc getQualifierLoc() const {
+    if (!hasQualifier())
+      return NestedNameSpecifierLoc();
+    return *getTrailingObjects<NestedNameSpecifierLoc>();
+  }
+
+  /// If the member name was qualified, retrieves the
+  /// nested-name-specifier that precedes the member name. Otherwise, returns
+  /// NULL.
   NestedNameSpecifier *getQualifier() const {
-    return QualifierLoc.getNestedNameSpecifier();
+    return getQualifierLoc().getNestedNameSpecifier();
   }
 
-  /// Retrieve the nested-name-specifier that qualifies the member
-  /// name, with source location information.
-  NestedNameSpecifierLoc getQualifierLoc() const { return QualifierLoc; }
 
+  #if 0
   /// Retrieve the first part of the nested-name-specifier that was
   /// found in the scope of the member access expression when the member access
   /// was initially parsed.
@@ -3808,6 +3832,13 @@ class CXXDependentScopeMemberExpr final
       return nullptr;
     return *getTrailingObjects<NamedDecl *>();
   }
+  #endif
+
+  ArrayRef<DeclAccessPair> unqualified_lookups() const {
+    if (!getNumUnqualifiedLookups())
+      return std::nullopt;
+    return {getTrailingObjects<DeclAccessPair>(), getNumUnqualifiedLookups()};
+  }
 
   /// Retrieve the name of the member that this expression refers to.
   const DeclarationNameInfo &getMemberNameInfo() const {

clang/include/clang/AST/Stmt.h

@@ -1020,18 +1020,25 @@ class alignas(void *) Stmt {
     LLVM_PREFERRED_TYPE(bool)
     unsigned IsArrow : 1;
 
+    /// True if this member expression used a nested-name-specifier to
+    /// refer to the member, e.g., "x->Base::f".
+    LLVM_PREFERRED_TYPE(bool)
+    unsigned HasQualifier : 1;
+
     /// Whether this member expression has info for explicit template
     /// keyword and arguments.
     LLVM_PREFERRED_TYPE(bool)
     unsigned HasTemplateKWAndArgsInfo : 1;
 
+    #if 0
     /// See getFirstQualifierFoundInScope() and the comment listing
     /// the trailing objects.
     LLVM_PREFERRED_TYPE(bool)
     unsigned HasFirstQualifierFoundInScope : 1;
-
-    /// The location of the '->' or '.' operator.
-    SourceLocation OperatorLoc;
+    #endif
+    /// Number of declarations found by unqualified lookup for the
+    /// first component name of the nested-name-specifier.
+    unsigned NumUnqualifiedLookups;
   };
 
   class OverloadExprBitfields {

clang/include/clang/AST/UnresolvedSet.h

@@ -96,6 +96,10 @@ class UnresolvedSetImpl {
     decls().push_back(DeclAccessPair::make(D, AS));
   }
 
+  void addAllDecls(ArrayRef<DeclAccessPair> Other) {
+    append(iterator(Other.begin()), iterator(Other.end()));
+  }
+
   /// Replaces the given declaration with the new one, once.
   ///
   /// \return true if the set changed

clang/include/clang/Sema/DeclSpec.h

@@ -75,7 +75,7 @@ class CXXScopeSpec {
   SourceRange Range;
   NestedNameSpecifierLocBuilder Builder;
   ArrayRef<TemplateParameterList *> TemplateParamLists;
-  NamedDecl *FoundFirstQualifierInScope;
+  ArrayRef<DeclAccessPair> UnqualifiedLookups;
 
 public:
   SourceRange getRange() const { return Range; }
@@ -92,11 +92,11 @@ class CXXScopeSpec {
     return TemplateParamLists;
   }
 
-  void setFoundFirstQualifierInScope(NamedDecl *Found) {
-    FoundFirstQualifierInScope = Found;
+  void setUnqualifiedLookups(ArrayRef<DeclAccessPair> Found) {
+    UnqualifiedLookups = Found;
   }
-  NamedDecl *getFirstQualifierFoundInScope() const {
-    return FoundFirstQualifierInScope;
+  ArrayRef<DeclAccessPair> getUnqualifiedLookups() const {
+    return UnqualifiedLookups;
   }
 
   /// Retrieve the representation of the nested-name-specifier.

clang/include/clang/Sema/Lookup.h

@@ -483,11 +483,15 @@ class LookupResult {
     ResultKind = Found;
   }
 
+  void addAllDecls(ArrayRef<DeclAccessPair> Other) {
+    Decls.addAllDecls(Other);
+    ResultKind = Found;
+  }
+
   /// Add all the declarations from another set of lookup
   /// results.
   void addAllDecls(const LookupResult &Other) {
-    Decls.append(Other.Decls.begin(), Other.Decls.end());
-    ResultKind = Found;
+    addAllDecls(Other.Decls.pairs());
   }
 
   /// Determine whether no result was found because we could not

clang/include/clang/Sema/Sema.h

@@ -2390,7 +2390,7 @@ class Sema final : public SemaBase {
 
   bool isAcceptableNestedNameSpecifier(const NamedDecl *SD,
                                        bool *CanCorrect = nullptr);
-  NamedDecl *FindFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS);
+  bool LookupFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS, UnresolvedSetImpl &R);
 
   /// Keeps information about an identifier in a nested-name-spec.
   ///
@@ -2423,7 +2423,6 @@ class Sema final : public SemaBase {
 
   bool BuildCXXNestedNameSpecifier(Scope *S, NestedNameSpecInfo &IdInfo,
                                    bool EnteringContext, CXXScopeSpec &SS,
-                                   NamedDecl *ScopeLookupResult,
                                    bool ErrorRecoveryLookup,
                                    bool *IsCorrectedToColon = nullptr,
                                    bool OnlyNamespace = false);
@@ -6938,7 +6937,7 @@ class Sema final : public SemaBase {
   ExprResult ActOnDependentMemberExpr(
       Expr *Base, QualType BaseType, bool IsArrow, SourceLocation OpLoc,
       const CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
-      NamedDecl *FirstQualifierInScope, const DeclarationNameInfo &NameInfo,
+      const DeclarationNameInfo &NameInfo,
       const TemplateArgumentListInfo *TemplateArgs);
 
   ExprResult ActOnMemberAccessExpr(Scope *S, Expr *Base, SourceLocation OpLoc,
@@ -6973,15 +6972,14 @@ class Sema final : public SemaBase {
   ExprResult BuildMemberReferenceExpr(
       Expr *Base, QualType BaseType, SourceLocation OpLoc, bool IsArrow,
       CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
-      NamedDecl *FirstQualifierInScope, const DeclarationNameInfo &NameInfo,
+      const DeclarationNameInfo &NameInfo,
       const TemplateArgumentListInfo *TemplateArgs, const Scope *S,
       ActOnMemberAccessExtraArgs *ExtraArgs = nullptr);
 
   ExprResult
   BuildMemberReferenceExpr(Expr *Base, QualType BaseType, SourceLocation OpLoc,
                            bool IsArrow, const CXXScopeSpec &SS,
-                           SourceLocation TemplateKWLoc,
-                           NamedDecl *FirstQualifierInScope, LookupResult &R,
+                           SourceLocation TemplateKWLoc, LookupResult &R,
                            const TemplateArgumentListInfo *TemplateArgs,
                            const Scope *S, bool SuppressQualifierCheck = false,
                            ActOnMemberAccessExtraArgs *ExtraArgs = nullptr);

clang/lib/AST/ASTImporter.cpp

@@ -8432,8 +8432,15 @@ ExpectedStmt ASTNodeImporter::VisitCXXDependentScopeMemberExpr(
   auto ToOperatorLoc = importChecked(Err, E->getOperatorLoc());
   auto ToQualifierLoc = importChecked(Err, E->getQualifierLoc());
   auto ToTemplateKeywordLoc = importChecked(Err, E->getTemplateKeywordLoc());
-  auto ToFirstQualifierFoundInScope =
-      importChecked(Err, E->getFirstQualifierFoundInScope());
+
+
+  UnresolvedSet<8> ToUnqualifiedLookups;
+  for (auto D : E->unqualified_lookups())
+    if (auto ToDOrErr = import(D.getDecl()))
+      ToUnqualifiedLookups.addDecl(*ToDOrErr);
+    else
+      return ToDOrErr.takeError();
+
   if (Err)
     return std::move(Err);
 
@@ -8467,7 +8474,7 @@ ExpectedStmt ASTNodeImporter::VisitCXXDependentScopeMemberExpr(
 
   return CXXDependentScopeMemberExpr::Create(
       Importer.getToContext(), ToBase, ToType, E->isArrow(), ToOperatorLoc,
-      ToQualifierLoc, ToTemplateKeywordLoc, ToFirstQualifierFoundInScope,
+      ToQualifierLoc, ToTemplateKeywordLoc, ToUnqualifiedLookups.pairs(),
       ToMemberNameInfo, ResInfo);
 }