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Reapply "[Clang] Implement resolution for CWG1835 (#92957)" #98547

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merged 2 commits into from
Jul 11, 2024

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Reapplies #92957, fixing an instance where the template keyword was missing prior to a dependent name in llvm/ADT/ArrayRef.h. An alias-declaration is used to work around [a bug affecting GCC releases before 11.1]](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94799) which rejects the use of the template keyword prior to the nested-name-specifier in the class member access (godbolt example here).

@sdkrystian sdkrystian requested review from Endilll and a team as code owners July 11, 2024 20:55
@llvmbot llvmbot added clang Clang issues not falling into any other category libc++ libc++ C++ Standard Library. Not GNU libstdc++. Not libc++abi. clang:frontend Language frontend issues, e.g. anything involving "Sema" clang:modules C++20 modules and Clang Header Modules coroutines C++20 coroutines llvm:adt labels Jul 11, 2024
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llvmbot commented Jul 11, 2024

@llvm/pr-subscribers-llvm-adt
@llvm/pr-subscribers-clang

@llvm/pr-subscribers-libcxx

Author: Krystian Stasiowski (sdkrystian)

Changes

Reapplies #92957, fixing an instance where the template keyword was missing prior to a dependent name in llvm/ADT/ArrayRef.h. An alias-declaration is used to work around [a bug affecting GCC releases before 11.1]](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94799) which rejects the use of the template keyword prior to the nested-name-specifier in the class member access (godbolt example here).


Patch is 156.84 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/98547.diff

47 Files Affected:

  • (modified) clang/docs/ReleaseNotes.rst (+3)
  • (modified) clang/include/clang/AST/ExprCXX.h (+49-43)
  • (modified) clang/include/clang/AST/Stmt.h (+8-7)
  • (modified) clang/include/clang/AST/UnresolvedSet.h (+4)
  • (modified) clang/include/clang/Basic/DiagnosticParseKinds.td (+1-3)
  • (modified) clang/include/clang/Parse/Parser.h (+5-9)
  • (modified) clang/include/clang/Sema/DeclSpec.h (+8)
  • (modified) clang/include/clang/Sema/Lookup.h (+6-2)
  • (modified) clang/include/clang/Sema/Sema.h (+22-32)
  • (modified) clang/lib/AST/ASTImporter.cpp (+9-3)
  • (modified) clang/lib/AST/ExprCXX.cpp (+40-27)
  • (modified) clang/lib/AST/ItaniumMangle.cpp (+15-24)
  • (modified) clang/lib/Parse/ParseExpr.cpp (+3-4)
  • (modified) clang/lib/Parse/ParseExprCXX.cpp (+50-45)
  • (modified) clang/lib/Sema/SemaCXXScopeSpec.cpp (+91-104)
  • (modified) clang/lib/Sema/SemaCoroutine.cpp (+2-2)
  • (modified) clang/lib/Sema/SemaDeclCXX.cpp (+23-24)
  • (modified) clang/lib/Sema/SemaExpr.cpp (+1-1)
  • (modified) clang/lib/Sema/SemaExprMember.cpp (+33-41)
  • (modified) clang/lib/Sema/SemaOverload.cpp (+5-7)
  • (modified) clang/lib/Sema/SemaStmtAsm.cpp (+5-3)
  • (modified) clang/lib/Sema/SemaTemplate.cpp (+105-113)
  • (modified) clang/lib/Sema/SemaTemplateInstantiate.cpp (+7-10)
  • (modified) clang/lib/Sema/TreeTransform.h (+131-198)
  • (modified) clang/lib/Serialization/ASTReaderStmt.cpp (+32-31)
  • (modified) clang/lib/Serialization/ASTWriterStmt.cpp (+25-18)
  • (modified) clang/test/CXX/basic/basic.lookup/basic.lookup.classref/p1-cxx11.cpp (+9-5)
  • (modified) clang/test/CXX/basic/basic.lookup/basic.lookup.classref/p1.cpp (+9-5)
  • (added) clang/test/CXX/basic/basic.lookup/basic.lookup.qual/basic.lookup.qual.general/p3-example3.cpp (+27)
  • (added) clang/test/CXX/basic/basic.lookup/basic.lookup.qual/basic.lookup.qual.general/p3.cpp (+98)
  • (modified) clang/test/CXX/class.derived/class.member.lookup/p8.cpp (+2-2)
  • (modified) clang/test/CXX/drs/cwg1xx.cpp (+4-4)
  • (added) clang/test/CXX/temp/temp.names/p3-23.cpp (+237)
  • (modified) clang/test/CXX/temp/temp.res/p3.cpp (+1-1)
  • (modified) clang/test/FixIt/fixit.cpp (+2-2)
  • (modified) clang/test/Misc/warning-flags.c (+1-1)
  • (modified) clang/test/Parser/cxx2a-concepts-requires-expr.cpp (+1-1)
  • (modified) clang/test/SemaCXX/cxx0x-noexcept-expression.cpp (+3-3)
  • (modified) clang/test/SemaCXX/pseudo-destructors.cpp (+9-9)
  • (modified) clang/test/SemaCXX/static-assert-cxx17.cpp (+1-1)
  • (modified) clang/test/SemaTemplate/dependent-base-classes.cpp (+10-10)
  • (modified) clang/test/SemaTemplate/dependent-template-recover.cpp (+6-6)
  • (modified) clang/test/SemaTemplate/temp_arg_nontype_cxx20.cpp (+1-1)
  • (modified) clang/test/SemaTemplate/template-id-expr.cpp (+7-7)
  • (modified) clang/test/SemaTemplate/typename-specifier-3.cpp (+1-1)
  • (modified) libcxx/include/regex (+1-1)
  • (modified) llvm/include/llvm/ADT/ArrayRef.h (+5-2)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index d5446f7fd92cc..be2f06766a755 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -310,6 +310,9 @@ Resolutions to C++ Defect Reports
 - Clang now considers ``noexcept(typeid(expr))`` more carefully, instead of always assuming that ``std::bad_typeid`` can be thrown.
   (`CWG2191: Incorrect result for noexcept(typeid(v)) <https://cplusplus.github.io/CWG/issues/2191.html>`_).
 
+- Clang now correctly implements lookup for the terminal name of a member-qualified nested-name-specifier.
+  (`CWG1835: Dependent member lookup before < <https://cplusplus.github.io/CWG/issues/1835.html>`_).
+
 C Language Changes
 ------------------
 
diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
index c2feac525c1ea..edaea6fe27cc3 100644
--- a/clang/include/clang/AST/ExprCXX.h
+++ b/clang/include/clang/AST/ExprCXX.h
@@ -3676,9 +3676,9 @@ class CXXUnresolvedConstructExpr final
 /// an implicit access if a qualifier is provided.
 class CXXDependentScopeMemberExpr final
     : public Expr,
-      private llvm::TrailingObjects<CXXDependentScopeMemberExpr,
-                                    ASTTemplateKWAndArgsInfo,
-                                    TemplateArgumentLoc, NamedDecl *> {
+      private llvm::TrailingObjects<
+          CXXDependentScopeMemberExpr, NestedNameSpecifierLoc, DeclAccessPair,
+          ASTTemplateKWAndArgsInfo, TemplateArgumentLoc> {
   friend class ASTStmtReader;
   friend class ASTStmtWriter;
   friend TrailingObjects;
@@ -3691,17 +3691,15 @@ 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:
   //
@@ -3721,8 +3719,16 @@ 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 {
@@ -3733,33 +3739,32 @@ 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,
+         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
@@ -3784,34 +3789,35 @@ class CXXDependentScopeMemberExpr final
   bool isArrow() const { return CXXDependentScopeMemberExprBits.IsArrow; }
 
   /// Retrieve the location of the '->' or '.' operator.
-  SourceLocation getOperatorLoc() const {
-    return CXXDependentScopeMemberExprBits.OperatorLoc;
+  SourceLocation getOperatorLoc() const { 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.
-  NestedNameSpecifier *getQualifier() const {
-    return QualifierLoc.getNestedNameSpecifier();
+  /// 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>();
   }
 
-  /// Retrieve the nested-name-specifier that qualifies the member
-  /// name, with source location information.
-  NestedNameSpecifierLoc getQualifierLoc() const { return QualifierLoc; }
+  /// If the member name was qualified, retrieves the
+  /// nested-name-specifier that precedes the member name. Otherwise, returns
+  /// NULL.
+  NestedNameSpecifier *getQualifier() const {
+    return getQualifierLoc().getNestedNameSpecifier();
+  }
 
-  /// 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.
-  ///
-  /// This function only returns a useful result when member access expression
-  /// uses a qualified member name, e.g., "x.Base::f". Here, the declaration
-  /// returned by this function describes what was found by unqualified name
-  /// lookup for the identifier "Base" within the scope of the member access
-  /// expression itself. At template instantiation time, this information is
-  /// combined with the results of name lookup into the type of the object
-  /// expression itself (the class type of x).
-  NamedDecl *getFirstQualifierFoundInScope() const {
-    if (!hasFirstQualifierFoundInScope())
-      return nullptr;
-    return *getTrailingObjects<NamedDecl *>();
+  /// Retrieve the declarations found by unqualified lookup for the first
+  /// component name of the nested-name-specifier, if any.
+  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.
diff --git a/clang/include/clang/AST/Stmt.h b/clang/include/clang/AST/Stmt.h
index 9cd7a364cd3f1..257a61c97c9c6 100644
--- a/clang/include/clang/AST/Stmt.h
+++ b/clang/include/clang/AST/Stmt.h
@@ -1020,18 +1020,19 @@ 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;
 
-    /// See getFirstQualifierFoundInScope() and the comment listing
-    /// the trailing objects.
-    LLVM_PREFERRED_TYPE(bool)
-    unsigned HasFirstQualifierFoundInScope : 1;
-
-    /// The location of the '->' or '.' operator.
-    SourceLocation OperatorLoc;
+    /// Number of declarations found by unqualified lookup for the
+    /// first component name of the nested-name-specifier.
+    unsigned NumUnqualifiedLookups;
   };
 
   class OverloadExprBitfields {
diff --git a/clang/include/clang/AST/UnresolvedSet.h b/clang/include/clang/AST/UnresolvedSet.h
index 1369725ab4e96..ef44499ce5926 100644
--- a/clang/include/clang/AST/UnresolvedSet.h
+++ b/clang/include/clang/AST/UnresolvedSet.h
@@ -97,6 +97,10 @@ 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
diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
index 12aab09f28556..0bd2e35bf2e31 100644
--- a/clang/include/clang/Basic/DiagnosticParseKinds.td
+++ b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -895,9 +895,7 @@ def missing_template_arg_list_after_template_kw : Extension<
   "keyword">, InGroup<DiagGroup<"missing-template-arg-list-after-template-kw">>,
   DefaultError;
 
-def err_missing_dependent_template_keyword : Error<
-  "use 'template' keyword to treat '%0' as a dependent template name">;
-def warn_missing_dependent_template_keyword : ExtWarn<
+def ext_missing_dependent_template_keyword : ExtWarn<
   "use 'template' keyword to treat '%0' as a dependent template name">;
 
 def ext_extern_template : Extension<
diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
index 6880fa4bb0b03..b4f5270a35956 100644
--- a/clang/include/clang/Parse/Parser.h
+++ b/clang/include/clang/Parse/Parser.h
@@ -3368,15 +3368,11 @@ class Parser : public CodeCompletionHandler {
   BaseResult ParseBaseSpecifier(Decl *ClassDecl);
   AccessSpecifier getAccessSpecifierIfPresent() const;
 
-  bool ParseUnqualifiedIdTemplateId(CXXScopeSpec &SS,
-                                    ParsedType ObjectType,
-                                    bool ObjectHadErrors,
-                                    SourceLocation TemplateKWLoc,
-                                    IdentifierInfo *Name,
-                                    SourceLocation NameLoc,
-                                    bool EnteringContext,
-                                    UnqualifiedId &Id,
-                                    bool AssumeTemplateId);
+  bool ParseUnqualifiedIdTemplateId(
+      CXXScopeSpec &SS, ParsedType ObjectType, bool ObjectHadErrors,
+      SourceLocation TemplateKWLoc, SourceLocation TildeLoc,
+      IdentifierInfo *Name, SourceLocation NameLoc, bool EnteringContext,
+      UnqualifiedId &Id, bool AssumeTemplateId);
   bool ParseUnqualifiedIdOperator(CXXScopeSpec &SS, bool EnteringContext,
                                   ParsedType ObjectType,
                                   UnqualifiedId &Result);
diff --git a/clang/include/clang/Sema/DeclSpec.h b/clang/include/clang/Sema/DeclSpec.h
index 425b6e2a0b30c..9c22c35535ede 100644
--- a/clang/include/clang/Sema/DeclSpec.h
+++ b/clang/include/clang/Sema/DeclSpec.h
@@ -75,6 +75,7 @@ class CXXScopeSpec {
   SourceRange Range;
   NestedNameSpecifierLocBuilder Builder;
   ArrayRef<TemplateParameterList *> TemplateParamLists;
+  ArrayRef<DeclAccessPair> UnqualifiedLookups;
 
 public:
   SourceRange getRange() const { return Range; }
@@ -91,6 +92,13 @@ class CXXScopeSpec {
     return TemplateParamLists;
   }
 
+  void setUnqualifiedLookups(ArrayRef<DeclAccessPair> Found) {
+    UnqualifiedLookups = Found;
+  }
+  ArrayRef<DeclAccessPair> getUnqualifiedLookups() const {
+    return UnqualifiedLookups;
+  }
+
   /// Retrieve the representation of the nested-name-specifier.
   NestedNameSpecifier *getScopeRep() const {
     return Builder.getRepresentation();
diff --git a/clang/include/clang/Sema/Lookup.h b/clang/include/clang/Sema/Lookup.h
index b0a08a05ac6a0..6b765ef3c980f 100644
--- a/clang/include/clang/Sema/Lookup.h
+++ b/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
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 57994f4033922..6be6f6725e5b7 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -2802,7 +2802,8 @@ class Sema final : public SemaBase {
   /// (e.g., Base::), perform name lookup for that identifier as a
   /// nested-name-specifier within the given scope, and return the result of
   /// that name lookup.
-  NamedDecl *FindFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS);
+  bool LookupFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS,
+                                   UnresolvedSetImpl &R);
 
   /// Keeps information about an identifier in a nested-name-spec.
   ///
@@ -2842,9 +2843,6 @@ class Sema final : public SemaBase {
   /// \param EnteringContext If true, enter the context specified by the
   ///        nested-name-specifier.
   /// \param SS Optional nested name specifier preceding the identifier.
-  /// \param ScopeLookupResult Provides the result of name lookup within the
-  ///        scope of the nested-name-specifier that was computed at template
-  ///        definition time.
   /// \param ErrorRecoveryLookup Specifies if the method is called to improve
   ///        error recovery and what kind of recovery is performed.
   /// \param IsCorrectedToColon If not null, suggestion of replace '::' -> ':'
@@ -2853,11 +2851,6 @@ class Sema final : public SemaBase {
   ///        not '::'.
   /// \param OnlyNamespace If true, only considers namespaces in lookup.
   ///
-  /// This routine differs only slightly from ActOnCXXNestedNameSpecifier, in
-  /// that it contains an extra parameter \p ScopeLookupResult, which provides
-  /// the result of name lookup within the scope of the nested-name-specifier
-  /// that was computed at template definition time.
-  ///
   /// If ErrorRecoveryLookup is true, then this call is used to improve error
   /// recovery.  This means that it should not emit diagnostics, it should
   /// just return true on failure.  It also means it should only return a valid
@@ -2866,7 +2859,6 @@ class Sema final : public SemaBase {
   /// specifier.
   bool BuildCXXNestedNameSpecifier(Scope *S, NestedNameSpecInfo &IdInfo,
                                    bool EnteringContext, CXXScopeSpec &SS,
-                                   NamedDecl *ScopeLookupResult,
                                    bool ErrorRecoveryLookup,
                                    bool *IsCorrectedToColon = nullptr,
                                    bool OnlyNamespace = false);
@@ -8566,11 +8558,12 @@ class Sema final : public SemaBase {
                           const TemplateArgumentListInfo *TemplateArgs,
                           bool IsDefiniteInstance, const Scope *S);
 
-  ExprResult ActOnDependentMemberExpr(
-      Expr *Base, QualType BaseType, bool IsArrow, SourceLocation OpLoc,
-      const CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
-      NamedDecl *FirstQualifierInScope, const DeclarationNameInfo &NameInfo,
-      const TemplateArgumentListInfo *TemplateArgs);
+  ExprResult
+  ActOnDependentMemberExpr(Expr *Base, QualType BaseType, bool IsArrow,
+                           SourceLocation OpLoc, const CXXScopeSpec &SS,
+                           SourceLocation TemplateKWLoc,
+                           const DeclarationNameInfo &NameInfo,
+                           const TemplateArgumentListInfo *TemplateArgs);
 
   /// The main callback when the parser finds something like
   ///   expression . [nested-name-specifier] identifier
@@ -8626,15 +8619,14 @@ 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);
@@ -11122,15 +11114,14 @@ class Sema final : public SemaBase {
                      QualType ObjectType, bool EnteringContext,
                      RequiredTemplateKind RequiredTemplate = SourceLocation(),
                      AssumedTemplateKind *ATK = nullptr,
-                     bool AllowTypoCorrection = true);
+                     bool AllowTypoCorrection = true, bool MayBeNNS = false);
 
-  TemplateNameKind isTemplateName(Scope *S, CXXScopeSpec &SS,
-                                  bool hasTemplateKeyword,
-                                  const UnqualifiedId &Name,
-                                  ParsedType ObjectType, bool EnteringContext,
-                                  TemplateTy &Template,
-                                  bool &MemberOfUnknownSpecialization,
-                                  bool Disambiguation = false);
+  TemplateNameKind
+  isTemplateName(Scope *S, CXXScopeSpec &SS, bool hasTemplateKeyword,
+                 const UnqualifiedId &Name, ParsedType ObjectType,
+                 bool EnteringContext, TemplateTy &Template,
+                 bool &MemberOfUnknownSpecialization,
+                 bool Disambiguation = false, bool MayBeNNS = false);
 
   /// Try to resolve an undeclared template name as a type template.
   ///
@@ -11459,12 +11450,11 @@ class Sema final : public SemaBase {
   /// For example, given "x.MetaFun::template apply", the scope specifier
   /// \p SS will be "MetaFun::", \p TemplateKWLoc contains the location
   /// of the "template" keyword, and "apply" is the \p Name.
-  TemplateNameKind ActOnTemplateName(Scope *S, CXXScopeSpec &SS,
-                                     SourceLocation TemplateKWLoc,
-                                     const UnqualifiedId &Name,
-                                     ParsedType ObjectType,
-                                     bool EnteringContext, TemplateTy &Template,
-                                     bool AllowInjectedClassName = false);
+  TemplateNameKind
+  ActOnTemplateName(Scope *S, CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
+                    const UnqualifiedId &Name, ParsedType ObjectType,
+                    bool EnteringContext, TemplateTy &Temp...
[truncated]

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llvmbot commented Jul 11, 2024

@llvm/pr-subscribers-clang-modules

Author: Krystian Stasiowski (sdkrystian)

Changes

Reapplies #92957, fixing an instance where the template keyword was missing prior to a dependent name in llvm/ADT/ArrayRef.h. An alias-declaration is used to work around [a bug affecting GCC releases before 11.1]](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94799) which rejects the use of the template keyword prior to the nested-name-specifier in the class member access (godbolt example here).


Patch is 156.84 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/98547.diff

47 Files Affected:

  • (modified) clang/docs/ReleaseNotes.rst (+3)
  • (modified) clang/include/clang/AST/ExprCXX.h (+49-43)
  • (modified) clang/include/clang/AST/Stmt.h (+8-7)
  • (modified) clang/include/clang/AST/UnresolvedSet.h (+4)
  • (modified) clang/include/clang/Basic/DiagnosticParseKinds.td (+1-3)
  • (modified) clang/include/clang/Parse/Parser.h (+5-9)
  • (modified) clang/include/clang/Sema/DeclSpec.h (+8)
  • (modified) clang/include/clang/Sema/Lookup.h (+6-2)
  • (modified) clang/include/clang/Sema/Sema.h (+22-32)
  • (modified) clang/lib/AST/ASTImporter.cpp (+9-3)
  • (modified) clang/lib/AST/ExprCXX.cpp (+40-27)
  • (modified) clang/lib/AST/ItaniumMangle.cpp (+15-24)
  • (modified) clang/lib/Parse/ParseExpr.cpp (+3-4)
  • (modified) clang/lib/Parse/ParseExprCXX.cpp (+50-45)
  • (modified) clang/lib/Sema/SemaCXXScopeSpec.cpp (+91-104)
  • (modified) clang/lib/Sema/SemaCoroutine.cpp (+2-2)
  • (modified) clang/lib/Sema/SemaDeclCXX.cpp (+23-24)
  • (modified) clang/lib/Sema/SemaExpr.cpp (+1-1)
  • (modified) clang/lib/Sema/SemaExprMember.cpp (+33-41)
  • (modified) clang/lib/Sema/SemaOverload.cpp (+5-7)
  • (modified) clang/lib/Sema/SemaStmtAsm.cpp (+5-3)
  • (modified) clang/lib/Sema/SemaTemplate.cpp (+105-113)
  • (modified) clang/lib/Sema/SemaTemplateInstantiate.cpp (+7-10)
  • (modified) clang/lib/Sema/TreeTransform.h (+131-198)
  • (modified) clang/lib/Serialization/ASTReaderStmt.cpp (+32-31)
  • (modified) clang/lib/Serialization/ASTWriterStmt.cpp (+25-18)
  • (modified) clang/test/CXX/basic/basic.lookup/basic.lookup.classref/p1-cxx11.cpp (+9-5)
  • (modified) clang/test/CXX/basic/basic.lookup/basic.lookup.classref/p1.cpp (+9-5)
  • (added) clang/test/CXX/basic/basic.lookup/basic.lookup.qual/basic.lookup.qual.general/p3-example3.cpp (+27)
  • (added) clang/test/CXX/basic/basic.lookup/basic.lookup.qual/basic.lookup.qual.general/p3.cpp (+98)
  • (modified) clang/test/CXX/class.derived/class.member.lookup/p8.cpp (+2-2)
  • (modified) clang/test/CXX/drs/cwg1xx.cpp (+4-4)
  • (added) clang/test/CXX/temp/temp.names/p3-23.cpp (+237)
  • (modified) clang/test/CXX/temp/temp.res/p3.cpp (+1-1)
  • (modified) clang/test/FixIt/fixit.cpp (+2-2)
  • (modified) clang/test/Misc/warning-flags.c (+1-1)
  • (modified) clang/test/Parser/cxx2a-concepts-requires-expr.cpp (+1-1)
  • (modified) clang/test/SemaCXX/cxx0x-noexcept-expression.cpp (+3-3)
  • (modified) clang/test/SemaCXX/pseudo-destructors.cpp (+9-9)
  • (modified) clang/test/SemaCXX/static-assert-cxx17.cpp (+1-1)
  • (modified) clang/test/SemaTemplate/dependent-base-classes.cpp (+10-10)
  • (modified) clang/test/SemaTemplate/dependent-template-recover.cpp (+6-6)
  • (modified) clang/test/SemaTemplate/temp_arg_nontype_cxx20.cpp (+1-1)
  • (modified) clang/test/SemaTemplate/template-id-expr.cpp (+7-7)
  • (modified) clang/test/SemaTemplate/typename-specifier-3.cpp (+1-1)
  • (modified) libcxx/include/regex (+1-1)
  • (modified) llvm/include/llvm/ADT/ArrayRef.h (+5-2)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index d5446f7fd92cc..be2f06766a755 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -310,6 +310,9 @@ Resolutions to C++ Defect Reports
 - Clang now considers ``noexcept(typeid(expr))`` more carefully, instead of always assuming that ``std::bad_typeid`` can be thrown.
   (`CWG2191: Incorrect result for noexcept(typeid(v)) <https://cplusplus.github.io/CWG/issues/2191.html>`_).
 
+- Clang now correctly implements lookup for the terminal name of a member-qualified nested-name-specifier.
+  (`CWG1835: Dependent member lookup before < <https://cplusplus.github.io/CWG/issues/1835.html>`_).
+
 C Language Changes
 ------------------
 
diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
index c2feac525c1ea..edaea6fe27cc3 100644
--- a/clang/include/clang/AST/ExprCXX.h
+++ b/clang/include/clang/AST/ExprCXX.h
@@ -3676,9 +3676,9 @@ class CXXUnresolvedConstructExpr final
 /// an implicit access if a qualifier is provided.
 class CXXDependentScopeMemberExpr final
     : public Expr,
-      private llvm::TrailingObjects<CXXDependentScopeMemberExpr,
-                                    ASTTemplateKWAndArgsInfo,
-                                    TemplateArgumentLoc, NamedDecl *> {
+      private llvm::TrailingObjects<
+          CXXDependentScopeMemberExpr, NestedNameSpecifierLoc, DeclAccessPair,
+          ASTTemplateKWAndArgsInfo, TemplateArgumentLoc> {
   friend class ASTStmtReader;
   friend class ASTStmtWriter;
   friend TrailingObjects;
@@ -3691,17 +3691,15 @@ 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:
   //
@@ -3721,8 +3719,16 @@ 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 {
@@ -3733,33 +3739,32 @@ 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,
+         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
@@ -3784,34 +3789,35 @@ class CXXDependentScopeMemberExpr final
   bool isArrow() const { return CXXDependentScopeMemberExprBits.IsArrow; }
 
   /// Retrieve the location of the '->' or '.' operator.
-  SourceLocation getOperatorLoc() const {
-    return CXXDependentScopeMemberExprBits.OperatorLoc;
+  SourceLocation getOperatorLoc() const { 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.
-  NestedNameSpecifier *getQualifier() const {
-    return QualifierLoc.getNestedNameSpecifier();
+  /// 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>();
   }
 
-  /// Retrieve the nested-name-specifier that qualifies the member
-  /// name, with source location information.
-  NestedNameSpecifierLoc getQualifierLoc() const { return QualifierLoc; }
+  /// If the member name was qualified, retrieves the
+  /// nested-name-specifier that precedes the member name. Otherwise, returns
+  /// NULL.
+  NestedNameSpecifier *getQualifier() const {
+    return getQualifierLoc().getNestedNameSpecifier();
+  }
 
-  /// 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.
-  ///
-  /// This function only returns a useful result when member access expression
-  /// uses a qualified member name, e.g., "x.Base::f". Here, the declaration
-  /// returned by this function describes what was found by unqualified name
-  /// lookup for the identifier "Base" within the scope of the member access
-  /// expression itself. At template instantiation time, this information is
-  /// combined with the results of name lookup into the type of the object
-  /// expression itself (the class type of x).
-  NamedDecl *getFirstQualifierFoundInScope() const {
-    if (!hasFirstQualifierFoundInScope())
-      return nullptr;
-    return *getTrailingObjects<NamedDecl *>();
+  /// Retrieve the declarations found by unqualified lookup for the first
+  /// component name of the nested-name-specifier, if any.
+  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.
diff --git a/clang/include/clang/AST/Stmt.h b/clang/include/clang/AST/Stmt.h
index 9cd7a364cd3f1..257a61c97c9c6 100644
--- a/clang/include/clang/AST/Stmt.h
+++ b/clang/include/clang/AST/Stmt.h
@@ -1020,18 +1020,19 @@ 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;
 
-    /// See getFirstQualifierFoundInScope() and the comment listing
-    /// the trailing objects.
-    LLVM_PREFERRED_TYPE(bool)
-    unsigned HasFirstQualifierFoundInScope : 1;
-
-    /// The location of the '->' or '.' operator.
-    SourceLocation OperatorLoc;
+    /// Number of declarations found by unqualified lookup for the
+    /// first component name of the nested-name-specifier.
+    unsigned NumUnqualifiedLookups;
   };
 
   class OverloadExprBitfields {
diff --git a/clang/include/clang/AST/UnresolvedSet.h b/clang/include/clang/AST/UnresolvedSet.h
index 1369725ab4e96..ef44499ce5926 100644
--- a/clang/include/clang/AST/UnresolvedSet.h
+++ b/clang/include/clang/AST/UnresolvedSet.h
@@ -97,6 +97,10 @@ 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
diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
index 12aab09f28556..0bd2e35bf2e31 100644
--- a/clang/include/clang/Basic/DiagnosticParseKinds.td
+++ b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -895,9 +895,7 @@ def missing_template_arg_list_after_template_kw : Extension<
   "keyword">, InGroup<DiagGroup<"missing-template-arg-list-after-template-kw">>,
   DefaultError;
 
-def err_missing_dependent_template_keyword : Error<
-  "use 'template' keyword to treat '%0' as a dependent template name">;
-def warn_missing_dependent_template_keyword : ExtWarn<
+def ext_missing_dependent_template_keyword : ExtWarn<
   "use 'template' keyword to treat '%0' as a dependent template name">;
 
 def ext_extern_template : Extension<
diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
index 6880fa4bb0b03..b4f5270a35956 100644
--- a/clang/include/clang/Parse/Parser.h
+++ b/clang/include/clang/Parse/Parser.h
@@ -3368,15 +3368,11 @@ class Parser : public CodeCompletionHandler {
   BaseResult ParseBaseSpecifier(Decl *ClassDecl);
   AccessSpecifier getAccessSpecifierIfPresent() const;
 
-  bool ParseUnqualifiedIdTemplateId(CXXScopeSpec &SS,
-                                    ParsedType ObjectType,
-                                    bool ObjectHadErrors,
-                                    SourceLocation TemplateKWLoc,
-                                    IdentifierInfo *Name,
-                                    SourceLocation NameLoc,
-                                    bool EnteringContext,
-                                    UnqualifiedId &Id,
-                                    bool AssumeTemplateId);
+  bool ParseUnqualifiedIdTemplateId(
+      CXXScopeSpec &SS, ParsedType ObjectType, bool ObjectHadErrors,
+      SourceLocation TemplateKWLoc, SourceLocation TildeLoc,
+      IdentifierInfo *Name, SourceLocation NameLoc, bool EnteringContext,
+      UnqualifiedId &Id, bool AssumeTemplateId);
   bool ParseUnqualifiedIdOperator(CXXScopeSpec &SS, bool EnteringContext,
                                   ParsedType ObjectType,
                                   UnqualifiedId &Result);
diff --git a/clang/include/clang/Sema/DeclSpec.h b/clang/include/clang/Sema/DeclSpec.h
index 425b6e2a0b30c..9c22c35535ede 100644
--- a/clang/include/clang/Sema/DeclSpec.h
+++ b/clang/include/clang/Sema/DeclSpec.h
@@ -75,6 +75,7 @@ class CXXScopeSpec {
   SourceRange Range;
   NestedNameSpecifierLocBuilder Builder;
   ArrayRef<TemplateParameterList *> TemplateParamLists;
+  ArrayRef<DeclAccessPair> UnqualifiedLookups;
 
 public:
   SourceRange getRange() const { return Range; }
@@ -91,6 +92,13 @@ class CXXScopeSpec {
     return TemplateParamLists;
   }
 
+  void setUnqualifiedLookups(ArrayRef<DeclAccessPair> Found) {
+    UnqualifiedLookups = Found;
+  }
+  ArrayRef<DeclAccessPair> getUnqualifiedLookups() const {
+    return UnqualifiedLookups;
+  }
+
   /// Retrieve the representation of the nested-name-specifier.
   NestedNameSpecifier *getScopeRep() const {
     return Builder.getRepresentation();
diff --git a/clang/include/clang/Sema/Lookup.h b/clang/include/clang/Sema/Lookup.h
index b0a08a05ac6a0..6b765ef3c980f 100644
--- a/clang/include/clang/Sema/Lookup.h
+++ b/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
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 57994f4033922..6be6f6725e5b7 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -2802,7 +2802,8 @@ class Sema final : public SemaBase {
   /// (e.g., Base::), perform name lookup for that identifier as a
   /// nested-name-specifier within the given scope, and return the result of
   /// that name lookup.
-  NamedDecl *FindFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS);
+  bool LookupFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS,
+                                   UnresolvedSetImpl &R);
 
   /// Keeps information about an identifier in a nested-name-spec.
   ///
@@ -2842,9 +2843,6 @@ class Sema final : public SemaBase {
   /// \param EnteringContext If true, enter the context specified by the
   ///        nested-name-specifier.
   /// \param SS Optional nested name specifier preceding the identifier.
-  /// \param ScopeLookupResult Provides the result of name lookup within the
-  ///        scope of the nested-name-specifier that was computed at template
-  ///        definition time.
   /// \param ErrorRecoveryLookup Specifies if the method is called to improve
   ///        error recovery and what kind of recovery is performed.
   /// \param IsCorrectedToColon If not null, suggestion of replace '::' -> ':'
@@ -2853,11 +2851,6 @@ class Sema final : public SemaBase {
   ///        not '::'.
   /// \param OnlyNamespace If true, only considers namespaces in lookup.
   ///
-  /// This routine differs only slightly from ActOnCXXNestedNameSpecifier, in
-  /// that it contains an extra parameter \p ScopeLookupResult, which provides
-  /// the result of name lookup within the scope of the nested-name-specifier
-  /// that was computed at template definition time.
-  ///
   /// If ErrorRecoveryLookup is true, then this call is used to improve error
   /// recovery.  This means that it should not emit diagnostics, it should
   /// just return true on failure.  It also means it should only return a valid
@@ -2866,7 +2859,6 @@ class Sema final : public SemaBase {
   /// specifier.
   bool BuildCXXNestedNameSpecifier(Scope *S, NestedNameSpecInfo &IdInfo,
                                    bool EnteringContext, CXXScopeSpec &SS,
-                                   NamedDecl *ScopeLookupResult,
                                    bool ErrorRecoveryLookup,
                                    bool *IsCorrectedToColon = nullptr,
                                    bool OnlyNamespace = false);
@@ -8566,11 +8558,12 @@ class Sema final : public SemaBase {
                           const TemplateArgumentListInfo *TemplateArgs,
                           bool IsDefiniteInstance, const Scope *S);
 
-  ExprResult ActOnDependentMemberExpr(
-      Expr *Base, QualType BaseType, bool IsArrow, SourceLocation OpLoc,
-      const CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
-      NamedDecl *FirstQualifierInScope, const DeclarationNameInfo &NameInfo,
-      const TemplateArgumentListInfo *TemplateArgs);
+  ExprResult
+  ActOnDependentMemberExpr(Expr *Base, QualType BaseType, bool IsArrow,
+                           SourceLocation OpLoc, const CXXScopeSpec &SS,
+                           SourceLocation TemplateKWLoc,
+                           const DeclarationNameInfo &NameInfo,
+                           const TemplateArgumentListInfo *TemplateArgs);
 
   /// The main callback when the parser finds something like
   ///   expression . [nested-name-specifier] identifier
@@ -8626,15 +8619,14 @@ 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);
@@ -11122,15 +11114,14 @@ class Sema final : public SemaBase {
                      QualType ObjectType, bool EnteringContext,
                      RequiredTemplateKind RequiredTemplate = SourceLocation(),
                      AssumedTemplateKind *ATK = nullptr,
-                     bool AllowTypoCorrection = true);
+                     bool AllowTypoCorrection = true, bool MayBeNNS = false);
 
-  TemplateNameKind isTemplateName(Scope *S, CXXScopeSpec &SS,
-                                  bool hasTemplateKeyword,
-                                  const UnqualifiedId &Name,
-                                  ParsedType ObjectType, bool EnteringContext,
-                                  TemplateTy &Template,
-                                  bool &MemberOfUnknownSpecialization,
-                                  bool Disambiguation = false);
+  TemplateNameKind
+  isTemplateName(Scope *S, CXXScopeSpec &SS, bool hasTemplateKeyword,
+                 const UnqualifiedId &Name, ParsedType ObjectType,
+                 bool EnteringContext, TemplateTy &Template,
+                 bool &MemberOfUnknownSpecialization,
+                 bool Disambiguation = false, bool MayBeNNS = false);
 
   /// Try to resolve an undeclared template name as a type template.
   ///
@@ -11459,12 +11450,11 @@ class Sema final : public SemaBase {
   /// For example, given "x.MetaFun::template apply", the scope specifier
   /// \p SS will be "MetaFun::", \p TemplateKWLoc contains the location
   /// of the "template" keyword, and "apply" is the \p Name.
-  TemplateNameKind ActOnTemplateName(Scope *S, CXXScopeSpec &SS,
-                                     SourceLocation TemplateKWLoc,
-                                     const UnqualifiedId &Name,
-                                     ParsedType ObjectType,
-                                     bool EnteringContext, TemplateTy &Template,
-                                     bool AllowInjectedClassName = false);
+  TemplateNameKind
+  ActOnTemplateName(Scope *S, CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
+                    const UnqualifiedId &Name, ParsedType ObjectType,
+                    bool EnteringContext, TemplateTy &Temp...
[truncated]

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@Endilll Endilll left a comment

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Changes to DR tests look good.

@sdkrystian
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@chapuni This fixes the Ubuntu-20.04 g++ build issues you brought up in #98252.

@sdkrystian sdkrystian requested a review from cor3ntin July 11, 2024 21:52
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I've confirmed it's fine. Thanks!

@sdkrystian sdkrystian merged commit ce4aada into llvm:main Jul 11, 2024
48 of 59 checks passed
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llvm-ci commented Jul 11, 2024

LLVM Buildbot has detected a new failure on builder openmp-offload-libc-amdgpu-runtime running on omp-vega20-1 while building clang,libcxx,llvm at step 10 "Add check check-offload".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/73/builds/1674

Here is the relevant piece of the build log for the reference:

Step 10 (Add check check-offload) failure: 1200 seconds without output running [b'ninja', b'-j 32', b'check-offload'], attempting to kill
...
PASS: libomptarget :: x86_64-pc-linux-gnu-LTO :: offloading/test_libc.cpp (776 of 786)
PASS: libomptarget :: x86_64-pc-linux-gnu-LTO :: offloading/bug49779.cpp (777 of 786)
PASS: libomptarget :: x86_64-pc-linux-gnu-LTO :: offloading/bug50022.cpp (778 of 786)
PASS: libomptarget :: x86_64-pc-linux-gnu-LTO :: offloading/bug53727.cpp (779 of 786)
PASS: libomptarget :: x86_64-pc-linux-gnu-LTO :: offloading/wtime.c (780 of 786)
PASS: libomptarget :: x86_64-pc-linux-gnu :: offloading/bug49021.cpp (781 of 786)
PASS: libomptarget :: x86_64-pc-linux-gnu :: offloading/std_complex_arithmetic.cpp (782 of 786)
PASS: libomptarget :: x86_64-pc-linux-gnu-LTO :: offloading/complex_reduction.cpp (783 of 786)
PASS: libomptarget :: x86_64-pc-linux-gnu-LTO :: offloading/std_complex_arithmetic.cpp (784 of 786)
PASS: libomptarget :: x86_64-pc-linux-gnu-LTO :: offloading/bug49021.cpp (785 of 786)
command timed out: 1200 seconds without output running [b'ninja', b'-j 32', b'check-offload'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=1228.515257

@glandium
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glandium commented Jul 12, 2024

This broke building abseil-cpp (cd75cb4ae32c46c84cef9a9c78b42174f22ed0ac as of writing).

STR:

In file included from /tmp/abseil-cpp/absl/status/status.cc:14:
In file included from /tmp/abseil-cpp/absl/status/status.h:66:
In file included from /tmp/abseil-cpp/absl/status/internal/status_internal.h:26:
In file included from /tmp/abseil-cpp/absl/container/inlined_vector.h:53:
In file included from /tmp/abseil-cpp/absl/container/internal/inlined_vector.h:32:
/tmp/abseil-cpp/absl/container/internal/compressed_tuple.h:251:42: error: no member named 'get' in the global namespace
  251 |     return std::move(*this).StorageT<I>::get();
      |                                        ~~^
/tmp/abseil-cpp/absl/container/internal/compressed_tuple.h:256:42: error: no member named 'get' in the global namespace
  256 |     return std::move(*this).StorageT<I>::get();
      |                                        ~~^
2 errors generated.

@glandium
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Well, I guess this is working as intended, as adding template before StorageT fixes it.

@sdkrystian
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@glandium Yes, clang considers std::move(*this) to be dependent so template is required there.

@glandium
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The sad part is that MSVC and some old versions of GCC don't like template being added here :(

@pranavk
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pranavk commented Jul 12, 2024

Could we perhaps put this behind a flag to help with the transition?

Some cases can already be silenced with -Wno-missing-dependent-template-keyword but cases like above in absl are hard errors and there are no workarounds.

@sdkrystian
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sdkrystian commented Jul 13, 2024

@pranavk see #98613.

edit: sorry, the error recovery that is currently performed will not detect cases where the template argument list does not contain a a type. i can look into this monday.

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7 participants