Include attributes on LabelStmts (forwarding from decls) in AST dumps

We apply this to add a test of the new label attribute instantiation support.

Author: ericastor

clang/examples/Attribute/Attribute.cpp

@@ -41,9 +41,9 @@ struct ExampleAttrInfo : public ParsedAttrInfo {
   bool diagAppertainsToDecl(Sema &S, const ParsedAttr &Attr,
                             const Decl *D) const override {
     // This attribute appertains to functions only.
-    if (!isa<FunctionDecl>(D)) {
+    if (!isa<FunctionDecl>(D) && !isa<LabelDecl>(D)) {
       S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type_str)
-          << Attr << Attr.isRegularKeywordAttribute() << "functions";
+          << Attr << Attr.isRegularKeywordAttribute() << "functions or labels";
       return false;
     }
     return true;
@@ -52,7 +52,7 @@ struct ExampleAttrInfo : public ParsedAttrInfo {
   AttrHandling handleDeclAttribute(Sema &S, Decl *D,
                                    const ParsedAttr &Attr) const override {
     // Check if the decl is at file scope.
-    if (!D->getDeclContext()->isFileContext()) {
+    if (!D->getDeclContext()->isFileContext() && !isa<LabelDecl>(D)) {
       unsigned ID = S.getDiagnostics().getCustomDiagID(
           DiagnosticsEngine::Error,
           "'example' attribute only allowed at file scope");

clang/include/clang/AST/ASTNodeTraverser.h

@@ -800,6 +800,11 @@ class ASTNodeTraverser
       Visit(A);
   }
 
+  void VisitLabelStmt(const LabelStmt *Node) {
+    for (const auto *A : Node->getDecl()->getAttrs())
+      Visit(A);
+  }
+
   void VisitCXXCatchStmt(const CXXCatchStmt *Node) {
     Visit(Node->getExceptionDecl());
   }

clang/test/Frontend/plugin-attribute.cpp

@@ -18,6 +18,9 @@ void fn2() __attribute__((example("somestring", 1, 2.0))) {
 }
 template <int N> void template_fn() __attribute__((example("template", N))) {
   __attribute__((example("def", N + 1))) for (int i = 0; i < 9; ++i) {}
+  __attribute__((example("ghi", N + 2)))
+label1:
+  for (int i = 0; i < 9; ++i) {}
 }
 void fn3() { template_fn<5>(); }
 // CHECK: -AttributedStmt 0x{{[0-9a-z]+}} {{<line:[0-9]+:[0-9]+(, col:[0-9]+)?>}}
@@ -44,6 +47,11 @@ void fn3() { template_fn<5>(); }
 // CHECK: -IntegerLiteral 0x{{[0-9a-z]+}} {{<line:[0-9]+:[0-9]+(, col:[0-9]+)?>}} 'int' 5
 // CHECK: -IntegerLiteral 0x{{[0-9a-z]+}} {{<col:[0-9]+(, col:[0-9]+)?>}} 'int' 1
 // CHECK: -AnnotateAttr 0x{{[0-9a-z]+}} {{<line:[0-9]+:[0-9]+(, col:[0-9]+)?>}} "example"
+// CHECK: -StringLiteral 0x{{[0-9a-z]+}} {{<col:[0-9]+(, col:[0-9]+)?>}} 'const char[{{[0-9]+}}]' lvalue "ghi"
+// CHECK: -BinaryOperator 0x{{[0-9a-z]+}} {{<col:[0-9]+(, col:[0-9]+)?>}} 'int' '+'
+// CHECK: -IntegerLiteral 0x{{[0-9a-z]+}} {{<line:[0-9]+:[0-9]+(, col:[0-9]+)?>}} 'int' 5
+// CHECK: -IntegerLiteral 0x{{[0-9a-z]+}} {{<col:[0-9]+(, col:[0-9]+)?>}} 'int' 2
+// CHECK: -AnnotateAttr 0x{{[0-9a-z]+}} {{<line:[0-9]+:[0-9]+(, col:[0-9]+)?>}} "example"
 // CHECK: -StringLiteral 0x{{[0-9a-z]+}} {{<col:[0-9]+(, col:[0-9]+)?>}} 'const char[{{[0-9]+}}]' lvalue "template"
 // CHECK: -IntegerLiteral 0x{{[0-9a-z]+}} {{<col:[0-9]+(, col:[0-9]+)?>}} 'int' 5