PR5066: If a declarator cannot have an identifier, and cannot possibly be

followed by an identifier, then diagnose an identifier as being a bogus part of
the declarator instead of tripping over it. Improves diagnostics for cases like

  std::vector<const int *p> my_vec;

llvm-svn: 186061

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -450,6 +450,7 @@ def err_invalid_operator_on_type : Error<
   "cannot use %select{dot|arrow}0 operator on a type">;
 def err_expected_unqualified_id : Error<
   "expected %select{identifier|unqualified-id}0">;
+def err_unexpected_unqualified_id : Error<"type-id cannot have a name">;
 def err_func_def_no_params : Error<
   "function definition does not declare parameters">;
 def err_expected_lparen_after_type : Error<

clang/include/clang/Sema/DeclSpec.h

@@ -1719,6 +1719,38 @@ public:
     llvm_unreachable("unknown context kind!");
   }
 
+  /// diagnoseIdentifier - Return true if the identifier is prohibited and
+  /// should be diagnosed (because it cannot be anything else).
+  bool diagnoseIdentifier() const {
+    switch (Context) {
+    case FileContext:
+    case KNRTypeListContext:
+    case MemberContext:
+    case BlockContext:
+    case ForContext:
+    case ConditionContext:
+    case PrototypeContext:
+    case TemplateParamContext:
+    case CXXCatchContext:
+    case ObjCCatchContext:
+    case TypeNameContext:
+    case ConversionIdContext:
+    case ObjCParameterContext:
+    case ObjCResultContext:
+    case BlockLiteralContext:
+    case CXXNewContext:
+    case LambdaExprContext:
+      return false;
+
+    case AliasDeclContext:
+    case AliasTemplateContext:
+    case TemplateTypeArgContext:
+    case TrailingReturnContext:
+      return true;
+    }
+    llvm_unreachable("unknown context kind!");
+  }
+
   /// mayBeFollowedByCXXDirectInit - Return true if the declarator can be
   /// followed by a C++ direct initializer, e.g. "int x(1);".
   bool mayBeFollowedByCXXDirectInit() const {

clang/lib/Parse/ParseDecl.cpp

@@ -4696,6 +4696,12 @@ void Parser::ParseDirectDeclarator(Declarator &D) {
     D.SetIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
     ConsumeToken();
     goto PastIdentifier;
+  } else if (Tok.is(tok::identifier) && D.diagnoseIdentifier()) {
+    Diag(Tok.getLocation(), diag::err_unexpected_unqualified_id)
+      << FixItHint::CreateRemoval(Tok.getLocation());
+    D.SetIdentifier(0, Tok.getLocation());
+    ConsumeToken();
+    goto PastIdentifier;
   }
 
   if (Tok.is(tok::l_paren)) {

clang/test/FixIt/fixit.cpp

@@ -307,3 +307,8 @@ namespace dtor_fixit {
     // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:6-[[@LINE-1]]:9}:"foo"
   };
 }
+
+namespace PR5066 {
+  template<typename T> struct X {};
+  X<int *p> x; // expected-error {{type-id cannot have a name}}
+}

clang/test/Parser/cxx-decl.cpp

@@ -187,6 +187,13 @@ namespace PR15017 {
 // Ensure we produce at least some diagnostic for attributes in C++98.
 [[]] struct S; // expected-error 2{{}}
 
+namespace PR5066 {
+  template<typename T> struct X {};
+  X<int N> x; // expected-error {{type-id cannot have a name}}
+
+  using T = int (*T)(); // expected-error {{type-id cannot have a name}} expected-warning {{C++11}}
+}
+
 // PR8380
 extern ""      // expected-error {{unknown linkage language}}
 test6a { ;// expected-error {{C++ requires a type specifier for all declarations}} \

clang/test/Parser/cxx-template-argument.cpp

@@ -5,7 +5,7 @@ template<typename T> struct A {};
 // Check for template argument lists followed by junk
 // FIXME: The diagnostics here aren't great...
 A<int+> int x; // expected-error {{expected '>'}} expected-error {{expected unqualified-id}}
-A<int x; // expected-error {{expected '>'}}
+A<int x; // expected-error {{type-id cannot have a name}} expected-error {{expected '>'}}
 
 // PR8912
 template <bool> struct S {};

clang/test/Parser/cxx0x-decl.cpp

@@ -73,3 +73,10 @@ enum E
 [[]] e;
 
 }
+
+namespace PR5066 {
+  using T = int (*f)(); // expected-error {{type-id cannot have a name}}
+  template<typename T> using U = int (*f)(); // expected-error {{type-id cannot have a name}}
+  auto f() -> int (*f)(); // expected-error {{type-id cannot have a name}}
+  auto g = []() -> int (*f)() {}; // expected-error {{type-id cannot have a name}}
+}