[Clang][Sema] Don't build CXXDependentScopeMemberExprs for potentially implicit class member access expressions

sdkrystian · sdkrystian · commit db264c719dfa · 2024-05-17T17:05:00.000-04:00
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
@@ -5374,11 +5374,9 @@ class Sema final : public SemaBase {
   bool UseArgumentDependentLookup(const CXXScopeSpec &SS, const LookupResult &R,
                                   bool HasTrailingLParen);
 
-  ExprResult
-  BuildQualifiedDeclarationNameExpr(CXXScopeSpec &SS,
-                                    const DeclarationNameInfo &NameInfo,
-                                    bool IsAddressOfOperand, const Scope *S,
-                                    TypeSourceInfo **RecoveryTSI = nullptr);
+  ExprResult BuildQualifiedDeclarationNameExpr(
+      CXXScopeSpec &SS, const DeclarationNameInfo &NameInfo,
+      bool IsAddressOfOperand, TypeSourceInfo **RecoveryTSI = nullptr);
 
   ExprResult BuildDeclarationNameExpr(const CXXScopeSpec &SS, LookupResult &R,
                                       bool NeedsADL,
@@ -8990,7 +8988,8 @@ class Sema final : public SemaBase {
   ExprResult
   BuildQualifiedTemplateIdExpr(CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
                                const DeclarationNameInfo &NameInfo,
-                               const TemplateArgumentListInfo *TemplateArgs);
+                               const TemplateArgumentListInfo *TemplateArgs,
+                               bool IsAddressOfOperand);
 
   TemplateNameKind ActOnTemplateName(Scope *S, CXXScopeSpec &SS,
                                      SourceLocation TemplateKWLoc,
diff --git a/clang/lib/Sema/SemaCXXScopeSpec.cpp b/clang/lib/Sema/SemaCXXScopeSpec.cpp
@@ -796,6 +796,14 @@ bool Sema::BuildCXXNestedNameSpecifier(Scope *S, NestedNameSpecInfo &IdInfo,
         Diag(IdInfo.IdentifierLoc,
              diag::ext_undeclared_unqual_id_with_dependent_base)
             << IdInfo.Identifier << ContainingClass;
+        // Fake up a nested-name-specifier that starts with the
+        // injected-class-name of the enclosing class.
+        QualType T = Context.getTypeDeclType(ContainingClass);
+        TypeLocBuilder TLB;
+        TLB.pushTrivial(Context, T, IdInfo.IdentifierLoc);
+        SS.Extend(Context, /*TemplateKWLoc=*/SourceLocation(),
+                  TLB.getTypeLocInContext(Context, T), IdInfo.IdentifierLoc);
+        // Add the identifier to form a dependent name.
         SS.Extend(Context, IdInfo.Identifier, IdInfo.IdentifierLoc,
                   IdInfo.CCLoc);
         return false;
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
@@ -2946,26 +2946,14 @@ Sema::ActOnIdExpression(Scope *S, CXXScopeSpec &SS,
 /// this path.
 ExprResult Sema::BuildQualifiedDeclarationNameExpr(
     CXXScopeSpec &SS, const DeclarationNameInfo &NameInfo,
-    bool IsAddressOfOperand, const Scope *S, TypeSourceInfo **RecoveryTSI) {
-  if (NameInfo.getName().isDependentName())
-    return BuildDependentDeclRefExpr(SS, /*TemplateKWLoc=*/SourceLocation(),
-                                     NameInfo, /*TemplateArgs=*/nullptr);
-
-  DeclContext *DC = computeDeclContext(SS, false);
-  if (!DC)
-    return BuildDependentDeclRefExpr(SS, /*TemplateKWLoc=*/SourceLocation(),
-                                     NameInfo, /*TemplateArgs=*/nullptr);
-
-  if (RequireCompleteDeclContext(SS, DC))
-    return ExprError();
-
+    bool IsAddressOfOperand, TypeSourceInfo **RecoveryTSI) {
   LookupResult R(*this, NameInfo, LookupOrdinaryName);
-  LookupQualifiedName(R, DC);
+  LookupParsedName(R, /*S=*/nullptr, &SS, /*ObjectType=*/QualType());
 
   if (R.isAmbiguous())
     return ExprError();
 
-  if (R.getResultKind() == LookupResult::NotFoundInCurrentInstantiation)
+  if (R.wasNotFoundInCurrentInstantiation() || SS.isInvalid())
     return BuildDependentDeclRefExpr(SS, /*TemplateKWLoc=*/SourceLocation(),
                                      NameInfo, /*TemplateArgs=*/nullptr);
 
@@ -2974,6 +2962,7 @@ ExprResult Sema::BuildQualifiedDeclarationNameExpr(
     // diagnostic during template instantiation is likely bogus, e.g. if a class
     // is invalid because it's derived from an invalid base class, then missing
     // members were likely supposed to be inherited.
+    DeclContext *DC = computeDeclContext(SS);
     if (const auto *CD = dyn_cast<CXXRecordDecl>(DC))
       if (CD->isInvalidDecl())
         return ExprError();
@@ -3017,16 +3006,14 @@ ExprResult Sema::BuildQualifiedDeclarationNameExpr(
     return ExprEmpty();
   }
 
-  // Defend against this resolving to an implicit member access. We usually
-  // won't get here if this might be a legitimate a class member (we end up in
-  // BuildMemberReferenceExpr instead), but this can be valid if we're forming
-  // a pointer-to-member or in an unevaluated context in C++11.
-  if (!R.empty() && (*R.begin())->isCXXClassMember() && !IsAddressOfOperand)
+  // If necessary, build an implicit class member access.
+  if (isPotentialImplicitMemberAccess(SS, R, IsAddressOfOperand))
     return BuildPossibleImplicitMemberExpr(SS,
                                            /*TemplateKWLoc=*/SourceLocation(),
-                                           R, /*TemplateArgs=*/nullptr, S);
+                                           R, /*TemplateArgs=*/nullptr,
+                                           /*S=*/nullptr);
 
-  return BuildDeclarationNameExpr(SS, R, /* ADL */ false);
+  return BuildDeclarationNameExpr(SS, R, /*ADL=*/false);
 }
 
 /// Cast a base object to a member's actual type.
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
@@ -726,44 +726,18 @@ Sema::ActOnDependentIdExpression(const CXXScopeSpec &SS,
                                  const DeclarationNameInfo &NameInfo,
                                  bool isAddressOfOperand,
                            const TemplateArgumentListInfo *TemplateArgs) {
-  DeclContext *DC = getFunctionLevelDeclContext();
-
-  // C++11 [expr.prim.general]p12:
-  //   An id-expression that denotes a non-static data member or non-static
-  //   member function of a class can only be used:
-  //   (...)
-  //   - if that id-expression denotes a non-static data member and it
-  //     appears in an unevaluated operand.
-  //
-  // If this might be the case, form a DependentScopeDeclRefExpr instead of a
-  // CXXDependentScopeMemberExpr. The former can instantiate to either
-  // DeclRefExpr or MemberExpr depending on lookup results, while the latter is
-  // always a MemberExpr.
-  bool MightBeCxx11UnevalField =
-      getLangOpts().CPlusPlus11 && isUnevaluatedContext();
-
-  // Check if the nested name specifier is an enum type.
-  bool IsEnum = false;
-  if (NestedNameSpecifier *NNS = SS.getScopeRep())
-    IsEnum = isa_and_nonnull<EnumType>(NNS->getAsType());
-
-  if (!MightBeCxx11UnevalField && !isAddressOfOperand && !IsEnum &&
-      isa<CXXMethodDecl>(DC) &&
-      cast<CXXMethodDecl>(DC)->isImplicitObjectMemberFunction()) {
-    QualType ThisType =
-        cast<CXXMethodDecl>(DC)->getThisType().getNonReferenceType();
-
-    // Since the 'this' expression is synthesized, we don't need to
-    // perform the double-lookup check.
-    NamedDecl *FirstQualifierInScope = nullptr;
+  if (SS.isEmpty()) {
+    QualType ThisType = getCurrentThisType();
+    if (ThisType.isNull())
+      return ExprError();
 
     return CXXDependentScopeMemberExpr::Create(
-        Context, /*This=*/nullptr, ThisType,
+        Context, /*Base=*/nullptr, ThisType,
         /*IsArrow=*/!Context.getLangOpts().HLSL,
-        /*Op=*/SourceLocation(), SS.getWithLocInContext(Context), TemplateKWLoc,
-        FirstQualifierInScope, NameInfo, TemplateArgs);
+        /*OperatorLoc=*/SourceLocation(),
+        /*QualifierLoc*/ NestedNameSpecifierLoc(), TemplateKWLoc,
+        /*FirstQualifierFoundInScope*/ nullptr, NameInfo, TemplateArgs);
   }
-
   return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
 }
 
@@ -772,13 +746,15 @@ Sema::BuildDependentDeclRefExpr(const CXXScopeSpec &SS,
                                 SourceLocation TemplateKWLoc,
                                 const DeclarationNameInfo &NameInfo,
                                 const TemplateArgumentListInfo *TemplateArgs) {
-  // DependentScopeDeclRefExpr::Create requires a valid QualifierLoc
-  NestedNameSpecifierLoc QualifierLoc = SS.getWithLocInContext(Context);
-  if (!QualifierLoc)
-    return ExprError();
+  // DependentScopeDeclRefExpr::Create requires a valid NestedNameSpecifierLoc
+  if (!SS.isValid())
+    return CreateRecoveryExpr(
+        SS.getBeginLoc(),
+        TemplateArgs ? TemplateArgs->getRAngleLoc() : NameInfo.getEndLoc(), {});
 
   return DependentScopeDeclRefExpr::Create(
-      Context, QualifierLoc, TemplateKWLoc, NameInfo, TemplateArgs);
+      Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
+      TemplateArgs);
 }
 
 
@@ -5747,50 +5723,36 @@ ExprResult Sema::BuildTemplateIdExpr(const CXXScopeSpec &SS,
 }
 
 // We actually only call this from template instantiation.
-ExprResult
-Sema::BuildQualifiedTemplateIdExpr(CXXScopeSpec &SS,
-                                   SourceLocation TemplateKWLoc,
-                                   const DeclarationNameInfo &NameInfo,
-                             const TemplateArgumentListInfo *TemplateArgs) {
-
+ExprResult Sema::BuildQualifiedTemplateIdExpr(
+    CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
+    const DeclarationNameInfo &NameInfo,
+    const TemplateArgumentListInfo *TemplateArgs, bool IsAddressOfOperand) {
   assert(TemplateArgs || TemplateKWLoc.isValid());
-  DeclContext *DC;
-  if (!(DC = computeDeclContext(SS, false)) ||
-      DC->isDependentContext() ||
-      RequireCompleteDeclContext(SS, DC))
-    return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
 
   LookupResult R(*this, NameInfo, LookupOrdinaryName);
-  if (LookupTemplateName(R, (Scope *)nullptr, SS, QualType(),
-                         /*Entering*/ false, TemplateKWLoc))
+  if (LookupTemplateName(R, /*S=*/nullptr, SS, /*ObjectType=*/QualType(),
+                         /*EnteringContext=*/false, TemplateKWLoc))
     return ExprError();
 
   if (R.isAmbiguous())
     return ExprError();
 
+  if (R.wasNotFoundInCurrentInstantiation() || SS.isInvalid())
+    return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
+
   if (R.empty()) {
+    DeclContext *DC = computeDeclContext(SS);
     Diag(NameInfo.getLoc(), diag::err_no_member)
       << NameInfo.getName() << DC << SS.getRange();
     return ExprError();
   }
 
-  auto DiagnoseTypeTemplateDecl = [&](TemplateDecl *Temp,
-                                      bool isTypeAliasTemplateDecl) {
-    Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_type_template)
-        << SS.getScopeRep() << NameInfo.getName().getAsString() << SS.getRange()
-        << isTypeAliasTemplateDecl;
-    Diag(Temp->getLocation(), diag::note_referenced_type_template)
-        << isTypeAliasTemplateDecl;
-    return CreateRecoveryExpr(NameInfo.getBeginLoc(), NameInfo.getEndLoc(), {});
-  };
-
-  if (ClassTemplateDecl *Temp = R.getAsSingle<ClassTemplateDecl>())
-    return DiagnoseTypeTemplateDecl(Temp, false);
-
-  if (TypeAliasTemplateDecl *Temp = R.getAsSingle<TypeAliasTemplateDecl>())
-    return DiagnoseTypeTemplateDecl(Temp, true);
+  // If necessary, build an implicit class member access.
+  if (isPotentialImplicitMemberAccess(SS, R, IsAddressOfOperand))
+    return BuildPossibleImplicitMemberExpr(SS, TemplateKWLoc, R, TemplateArgs,
+                                           /*S=*/nullptr);
 
-  return BuildTemplateIdExpr(SS, TemplateKWLoc, R, /*ADL*/ false, TemplateArgs);
+  return BuildTemplateIdExpr(SS, TemplateKWLoc, R, /*ADL=*/false, TemplateArgs);
 }
 
 /// Form a template name from a name that is syntactically required to name a
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
@@ -3478,11 +3478,11 @@ class TreeTransform {
     SS.Adopt(QualifierLoc);
 
     if (TemplateArgs || TemplateKWLoc.isValid())
-      return getSema().BuildQualifiedTemplateIdExpr(SS, TemplateKWLoc, NameInfo,
-                                                    TemplateArgs);
+      return getSema().BuildQualifiedTemplateIdExpr(
+          SS, TemplateKWLoc, NameInfo, TemplateArgs, IsAddressOfOperand);
 
     return getSema().BuildQualifiedDeclarationNameExpr(
-        SS, NameInfo, IsAddressOfOperand, /*S*/nullptr, RecoveryTSI);
+        SS, NameInfo, IsAddressOfOperand, RecoveryTSI);
   }
 
   /// Build a new template-id expression.
diff --git a/clang/test/CXX/class/class.mfct/class.mfct.non-static/p3.cpp b/clang/test/CXX/class/class.mfct/class.mfct.non-static/p3.cpp
@@ -70,7 +70,7 @@ namespace test2 {
     }
 
     void test1() {
-      B<T>::foo();
+      B<T>::foo(); // expected-error {{call to non-static member function without an object argument}}
     }
 
     static void test2() {
@@ -91,8 +91,95 @@ namespace test2 {
   int test() {
     A<int> a;
     a.test0(); // no instantiation note here, decl is ill-formed
-    a.test1();
+    a.test1(); // expected-note {{in instantiation}}
     a.test2(); // expected-note {{in instantiation}}
     a.test3(); // expected-note {{in instantiation}}
   }
 }
+
+namespace test3 {
+  struct A {
+    void f0();
+
+    template<typename T>
+    void f1();
+
+    static void f2();
+
+    template<typename T>
+    static void f3();
+
+    int x0;
+
+    static constexpr int x1 = 0;
+
+    template<typename T>
+    static constexpr int x2 = 0;
+  };
+
+  template<typename T>
+  struct B : T {
+    auto g0() -> decltype(T::f0());
+
+    auto g1() -> decltype(T::template f1<int>());
+
+    auto g2() -> decltype(T::f2());
+
+    auto g3() -> decltype(T::template f3<int>());
+
+    auto g4() -> decltype(T::x0);
+
+    auto g5() -> decltype(T::x1);
+
+    auto g6() -> decltype(T::template x2<int>);
+
+    decltype(T::f0()) g7(); // expected-error {{call to non-static member function without an object argument}}
+
+    decltype(T::template f1<int>()) g8(); // expected-error {{call to non-static member function without an object argument}}
+
+    decltype(T::f2()) g9();
+
+    decltype(T::template f3<int>()) g10();
+
+    decltype(T::x0) g11();
+
+    decltype(T::x1) g12();
+
+    decltype(T::template x2<int>) g13();
+  };
+
+  template struct B<A>; // expected-note {{in instantiation of}}
+
+  template<typename T>
+  struct C : T {
+    static auto g0() -> decltype(T::f0()); // expected-error {{'this' cannot be implicitly used in a static member function declaration}}
+
+    static auto g1() -> decltype(T::template f1<int>()); // expected-error {{'this' cannot be implicitly used in a static member function declaration}}
+
+    static auto g2() -> decltype(T::f2());
+
+    static auto g3() -> decltype(T::template f3<int>());
+
+    static auto g4() -> decltype(T::x0); // expected-error {{'this' cannot be implicitly used in a static member function declaration}}
+
+    static auto g5() -> decltype(T::x1);
+
+    static auto g6() -> decltype(T::template x2<int>);
+
+    static decltype(T::f0()) g7(); // expected-error {{call to non-static member function without an object argument}}
+
+    static decltype(T::template f1<int>()) g8(); // expected-error {{call to non-static member function without an object argument}}
+
+    static decltype(T::f2()) g9();
+
+    static decltype(T::template f3<int>()) g10();
+
+    static decltype(T::x0) g11();
+
+    static decltype(T::x1) g12();
+
+    static decltype(T::template x2<int>) g13();
+  };
+
+  template struct C<A>; // expected-note {{in instantiation of}}
+}
diff --git a/clang/test/SemaTemplate/ms-function-specialization-class-scope.cpp b/clang/test/SemaTemplate/ms-function-specialization-class-scope.cpp
diff --git a/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp b/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp
diff --git a/clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp b/clang/unittests/ASTMatchers/ASTMatchersNodeTest.cpp
