commit 76f888d0a5324f4c6ae89cac61077cca4299b159
author Richard Smith <richard@metafoo.co.uk> Mon Feb 10 02:17:43 2020 -0800
committer Richard Smith <richard@metafoo.co.uk> Mon Feb 10 02:21:01 2020 -0800
tree 9b475d3d9a7b26885fa54477e721b11961fdf31e
parent 3a4dc577c97218c4915f18108ed9945be8250289

Fix handling of destructor names that name typedefs.

1) Fix a regression in llvmorg-11-init-2485-g0e3a4877840 that would
reject some cases where a class name is shadowed by a typedef-name
causing a destructor declaration to be rejected. Prefer a tag type over
a typedef in destructor name lookup.

2) Convert the "type in destructor declaration is a typedef" error to an
error-by-default ExtWarn to allow codebases to turn it off. GCC and MSVC
do not enforce this rule.

clang/lib/Sema/SemaDeclCXX.cpp

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index a1f7806..7331c33 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -9986,12 +9986,12 @@
   //   declaration.
   QualType DeclaratorType = GetTypeFromParser(D.getName().DestructorName);
   if (const TypedefType *TT = DeclaratorType->getAs<TypedefType>())
-    Diag(D.getIdentifierLoc(), diag::err_destructor_typedef_name)
+    Diag(D.getIdentifierLoc(), diag::ext_destructor_typedef_name)
       << DeclaratorType << isa<TypeAliasDecl>(TT->getDecl());
   else if (const TemplateSpecializationType *TST =
              DeclaratorType->getAs<TemplateSpecializationType>())
     if (TST->isTypeAlias())
-      Diag(D.getIdentifierLoc(), diag::err_destructor_typedef_name)
+      Diag(D.getIdentifierLoc(), diag::ext_destructor_typedef_name)
         << DeclaratorType << 1;
 
   // C++ [class.dtor]p2:

clang/lib/Sema/SemaExprCXX.cpp

diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index a39b0b1..8333385 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -201,11 +201,9 @@
 
     if (TypeDecl *Type = Found.getAsSingle<TypeDecl>()) {
       QualType T = Context.getTypeDeclType(Type);
-      MarkAnyDeclReferenced(Type->getLocation(), Type, /*OdrUse=*/false);
-
       if (SearchType.isNull() || SearchType->isDependentType() ||
           Context.hasSameUnqualifiedType(T, SearchType)) {
-        // We found our type!
+        MarkAnyDeclReferenced(Type->getLocation(), Type, /*OdrUse=*/false);
         return CreateParsedType(T,
                                 Context.getTrivialTypeSourceInfo(T, NameLoc));
       }
@@ -222,7 +220,7 @@
 
     IsDependent |= SearchType->isDependentType();
 
-    LookupResult Found(*this, &II, NameLoc, LookupOrdinaryName);
+    LookupResult Found(*this, &II, NameLoc, LookupDestructorName);
     DeclContext *LookupCtx = computeDeclContext(SearchType);
     if (!LookupCtx)
       return nullptr;
@@ -239,7 +237,7 @@
     if (!LookupCtx)
       return nullptr;
 
-    LookupResult Found(*this, &II, NameLoc, LookupOrdinaryName);
+    LookupResult Found(*this, &II, NameLoc, LookupDestructorName);
     if (RequireCompleteDeclContext(LookupSS, LookupCtx)) {
       Failed = true;
       return nullptr;
@@ -252,7 +250,7 @@
     if (Failed || !S)
       return nullptr;
 
-    LookupResult Found(*this, &II, NameLoc, LookupOrdinaryName);
+    LookupResult Found(*this, &II, NameLoc, LookupDestructorName);
     LookupName(Found, S);
     return CheckLookupResult(Found);
   };

clang/lib/Sema/SemaLookup.cpp

diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 8d96404..82a1971 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -215,6 +215,7 @@
   case Sema::LookupOrdinaryName:
   case Sema::LookupRedeclarationWithLinkage:
   case Sema::LookupLocalFriendName:
+  case Sema::LookupDestructorName:
     IDNS = Decl::IDNS_Ordinary;
     if (CPlusPlus) {
       IDNS |= Decl::IDNS_Tag | Decl::IDNS_Member | Decl::IDNS_Namespace;
@@ -378,11 +379,14 @@
   // type), per a generous reading of C++ [dcl.typedef]p3 and p4. The typedef
   // might carry additional semantic information, such as an alignment override.
   // However, per C++ [dcl.typedef]p5, when looking up a tag name, prefer a tag
-  // declaration over a typedef.
+  // declaration over a typedef. Also prefer a tag over a typedef for
+  // destructor name lookup because in some contexts we only accept a
+  // class-name in a destructor declaration.
   if (DUnderlying->getCanonicalDecl() != EUnderlying->getCanonicalDecl()) {
     assert(isa<TypeDecl>(DUnderlying) && isa<TypeDecl>(EUnderlying));
     bool HaveTag = isa<TagDecl>(EUnderlying);
-    bool WantTag = Kind == Sema::LookupTagName;
+    bool WantTag =
+        Kind == Sema::LookupTagName || Kind == Sema::LookupDestructorName;
     return HaveTag != WantTag;
   }
 
@@ -2297,6 +2301,7 @@
     case LookupMemberName:
     case LookupRedeclarationWithLinkage:
     case LookupLocalFriendName:
+    case LookupDestructorName:
       BaseCallback = &CXXRecordDecl::FindOrdinaryMember;
       break;