Allow attributes before union definition

permits typedef union __attribute__((transparent_union)) {...}

Differential Revision: https://reviews.llvm.org/D28266

llvm-svn: 296518

clang/include/clang/Sema/Sema.h

@@ -3122,6 +3122,8 @@ public:
   void ProcessPragmaWeak(Scope *S, Decl *D);
   // Decl attributes - this routine is the top level dispatcher.
   void ProcessDeclAttributes(Scope *S, Decl *D, const Declarator &PD);
+  // Helper for delayed proccessing of attributes.
+  void ProcessDeclAttributeDelayed(Decl *D, const AttributeList *AttrList);
   void ProcessDeclAttributeList(Scope *S, Decl *D, const AttributeList *AL,
                                 bool IncludeCXX11Attributes = true);
   bool ProcessAccessDeclAttributeList(AccessSpecDecl *ASDecl,

clang/lib/Parse/ParseDeclCXX.cpp

@@ -1887,6 +1887,10 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
       ParseStructUnionBody(StartLoc, TagType, TagOrTempResult.get());
   }
 
+  if (!TagOrTempResult.isInvalid())
+    // Delayed proccessing of attributes.
+    Actions.ProcessDeclAttributeDelayed(TagOrTempResult.get(), attrs.getList());
+
   const char *PrevSpec = nullptr;
   unsigned DiagID;
   bool Result;

clang/lib/Sema/SemaDecl.cpp

@@ -13637,9 +13637,6 @@ CreateNewDecl:
   if (Invalid)
     New->setInvalidDecl();
 
-  if (Attr)
-    ProcessDeclAttributeList(S, New, Attr);
-
   // Set the lexical context. If the tag has a C++ scope specifier, the
   // lexical context will be different from the semantic context.
   New->setLexicalDeclContext(CurContext);
@@ -13658,6 +13655,9 @@ CreateNewDecl:
   if (TUK == TUK_Definition)
     New->startDefinition();
 
+  if (Attr)
+    ProcessDeclAttributeList(S, New, Attr);
+
   // If this has an identifier, add it to the scope stack.
   if (TUK == TUK_Friend) {
     // We might be replacing an existing declaration in the lookup tables;

clang/lib/Sema/SemaDeclAttr.cpp

@@ -3193,8 +3193,9 @@ static void handleTransparentUnionAttr(Sema &S, Decl *D,
   }
 
   if (!RD->isCompleteDefinition()) {
-    S.Diag(Attr.getLoc(),
-        diag::warn_transparent_union_attribute_not_definition);
+    if (!RD->isBeingDefined())
+      S.Diag(Attr.getLoc(),
+             diag::warn_transparent_union_attribute_not_definition);
     return;
   }
 
@@ -6314,6 +6315,15 @@ void Sema::ProcessDeclAttributeList(Scope *S, Decl *D,
   }
 }
 
+// Helper for delayed proccessing TransparentUnion attribute.
+void Sema::ProcessDeclAttributeDelayed(Decl *D, const AttributeList *AttrList) {
+  for (const AttributeList *Attr = AttrList; Attr; Attr = Attr->getNext())
+    if (Attr->getKind() == AttributeList::AT_TransparentUnion) {
+      handleTransparentUnionAttr(*this, D, *Attr);
+      break;
+    }
+}
+
 // Annotation attributes are the only attributes allowed after an access
 // specifier.
 bool Sema::ProcessAccessDeclAttributeList(AccessSpecDecl *ASDecl,

clang/test/CodeGen/transparent-union.c

@@ -3,10 +3,21 @@
 // RUN: %clang_cc1 -Werror -triple armv7-linux -emit-llvm -o - %s | FileCheck %s --check-prefix=ARM
 // RUN: %clang_cc1 -Werror -triple powerpc64le-linux -emit-llvm -o - %s | FileCheck %s
 // RUN: %clang_cc1 -Werror -triple aarch64-linux -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -DINFRONT -Werror -triple x86_64-linux -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -DINFRONT -Werror -triple i386-linux -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -DINFRONT -Werror -triple armv7-linux -emit-llvm -o - %s | FileCheck %s --check-prefix=ARM
+// RUN: %clang_cc1 -DINFRONT -Werror -triple powerpc64le-linux -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -DINFRONT -Werror -triple aarch64-linux -emit-llvm -o - %s | FileCheck %s
 
+#ifdef INFRONT
+typedef union __attribute__((transparent_union)) {
+  void *f0;
+} transp_t0;
+#else
 typedef union {
   void *f0;
 } transp_t0 __attribute__((transparent_union));
+#endif
 
 void f0(transp_t0 obj);
 

clang/test/Sema/transparent-union.c

@@ -54,11 +54,21 @@ typedef union {
   aligned_struct8 s8; // expected-warning{{alignment of field}}
 } TU1 __attribute__((transparent_union));
 
+typedef union __attribute__((transparent_union)) {
+  aligned_struct4 s4; // expected-note{{alignment of first field}}
+  aligned_struct8 s8; // expected-warning{{alignment of field}}
+} TU1b ;
+
 typedef union {
   char c; // expected-note{{size of first field is 8 bits}}
   int i; // expected-warning{{size of field}}
 } TU2 __attribute__((transparent_union));
 
+typedef union __attribute__((transparent_union)){
+  char c; // expected-note{{size of first field is 8 bits}}
+  int i; // expected-warning{{size of field}}
+} TU2b;
+
 typedef union {
   float f; // expected-warning{{floating}}
 } TU3 __attribute__((transparent_union));
@@ -98,3 +108,17 @@ union pr30520a { int b[]; } __attribute__((transparent_union)); // expected-erro
 union pr30520s { struct stb b; } __attribute__((transparent_union)); // expected-error {{field has incomplete type 'struct stb'}}
 
 union pr30520s2 { int *v; struct stb b; } __attribute__((transparent_union)); // expected-error {{field has incomplete type 'struct stb'}}
+
+typedef union __attribute__((__transparent_union__)) {
+  int *i;
+  struct st *s;
+} TU6;
+
+void bar(TU6);
+
+void foo11(int *i) {
+  bar(i);
+}
+void foo2(struct st *s) {
+  bar(s);
+}