r243940 - [modules] Make IndirectFieldDecl mergeable to avoid lookup ambiguity when the same anonymous union is defined across multiple modules.

[Richard Smith]

Author: rsmith
Date: Mon Aug  3 21:05:09 2015
New Revision: 243940

URL: http://llvm.org/viewvc/llvm-project?rev=243940&view=rev
Log:
[modules] Make IndirectFieldDecl mergeable to avoid lookup ambiguity when the same anonymous union is defined across multiple modules.

Modified:
    cfe/trunk/include/clang/AST/Decl.h
    cfe/trunk/lib/Serialization/ASTReaderDecl.cpp
    cfe/trunk/test/Modules/Inputs/submodules-merge-defs/defs.h
    cfe/trunk/test/Modules/submodules-merge-defs.cpp

Modified: cfe/trunk/include/clang/AST/Decl.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Decl.h?rev=243940&r1=243939&r2=243940&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/Decl.h (original)
+++ cfe/trunk/include/clang/AST/Decl.h Mon Aug  3 21:05:09 2015
@@ -2499,7 +2499,8 @@ public:
 /// IndirectFieldDecl - An instance of this class is created to represent a
 /// field injected from an anonymous union/struct into the parent scope.
 /// IndirectFieldDecl are always implicit.
-class IndirectFieldDecl : public ValueDecl {
+class IndirectFieldDecl : public ValueDecl,
+                          public Mergeable<IndirectFieldDecl> {
   void anchor() override;
   NamedDecl **Chaining;
   unsigned ChainingSize;
@@ -2537,6 +2538,9 @@ public:
     return dyn_cast<VarDecl>(*chain_begin());
   }
 
+  IndirectFieldDecl *getCanonicalDecl() override { return getFirstDecl(); }
+  const IndirectFieldDecl *getCanonicalDecl() const { return getFirstDecl(); }
+
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
   static bool classofKind(Kind K) { return K == IndirectField; }

Modified: cfe/trunk/lib/Serialization/ASTReaderDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTReaderDecl.cpp?rev=243940&r1=243939&r2=243940&view=diff
==============================================================================
--- cfe/trunk/lib/Serialization/ASTReaderDecl.cpp (original)
+++ cfe/trunk/lib/Serialization/ASTReaderDecl.cpp Mon Aug  3 21:05:09 2015
@@ -1178,6 +1178,8 @@ void ASTDeclReader::VisitIndirectFieldDe
 
   for (unsigned I = 0; I != FD->ChainingSize; ++I)
     FD->Chaining[I] = ReadDeclAs<NamedDecl>(Record, Idx);
+
+  mergeMergeable(FD);
 }
 
 ASTDeclReader::RedeclarableResult ASTDeclReader::VisitVarDeclImpl(VarDecl *VD) {
@@ -2638,6 +2640,13 @@ static bool isSameEntity(NamedDecl *X, N
     return X->getASTContext().hasSameType(FDX->getType(), FDY->getType());
   }
 
+  // Indirect fields with the same target field match.
+  if (auto *IFDX = dyn_cast<IndirectFieldDecl>(X)) {
+    auto *IFDY = cast<IndirectFieldDecl>(Y);
+    return IFDX->getAnonField()->getCanonicalDecl() ==
+           IFDY->getAnonField()->getCanonicalDecl();
+  }
+
   // Enumerators with the same name match.
   if (isa<EnumConstantDecl>(X))
     // FIXME: Also check the value is odr-equivalent.

Modified: cfe/trunk/test/Modules/Inputs/submodules-merge-defs/defs.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Modules/Inputs/submodules-merge-defs/defs.h?rev=243940&r1=243939&r2=243940&view=diff
==============================================================================
--- cfe/trunk/test/Modules/Inputs/submodules-merge-defs/defs.h (original)
+++ cfe/trunk/test/Modules/Inputs/submodules-merge-defs/defs.h Mon Aug  3 21:05:09 2015
@@ -103,3 +103,11 @@ namespace RedeclDifferentDeclKind {
   typedef X X;
   using RedeclDifferentDeclKind::X;
 }
+
+namespace Anon {
+  struct X {
+    union {
+      int n;
+    };
+  };
+}

Modified: cfe/trunk/test/Modules/submodules-merge-defs.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Modules/submodules-merge-defs.cpp?rev=243940&r1=243939&r2=243940&view=diff
==============================================================================
--- cfe/trunk/test/Modules/submodules-merge-defs.cpp (original)
+++ cfe/trunk/test/Modules/submodules-merge-defs.cpp Mon Aug  3 21:05:09 2015
@@ -104,6 +104,7 @@ template<typename T, int N, template<typ
 J<> post_j2;
 FriendDefArg::Y<int> friend_def_arg;
 FriendDefArg::D<> friend_def_arg_d;
+int post_anon_x_n = Anon::X().n;
 
 MergeFunctionTemplateSpecializations::X<int>::Q<char> xiqc;