r224451 - Don't build invalid AST nodes during recovery

[Reid Kleckner]

Author: rnk
Date: Wed Dec 17 13:34:15 2014
New Revision: 224451

URL: http://llvm.org/viewvc/llvm-project?rev=224451&view=rev
Log:
Don't build invalid AST nodes during recovery

A DependentScopeDeclRefExpr should always have a nested name specifier.
During template instantiation, if we found that the named context was
incomplete, we would previously build a DependentScopeDeclRefExpr with
an empty qualifier.

This error recovery path has been asserting for some time. The other
error codepaths use ExprError, so we can do the same.

Fixes PR21864.

Modified:
    cfe/trunk/lib/Sema/SemaTemplate.cpp
    cfe/trunk/test/SemaTemplate/instantiate-dependent-nested-name.cpp

Modified: cfe/trunk/lib/Sema/SemaTemplate.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaTemplate.cpp?rev=224451&r1=224450&r2=224451&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaTemplate.cpp (original)
+++ cfe/trunk/lib/Sema/SemaTemplate.cpp Wed Dec 17 13:34:15 2014
@@ -2877,7 +2877,7 @@ Sema::BuildQualifiedTemplateIdExpr(CXXSc
   if (!(DC = computeDeclContext(SS, false)) ||
       DC->isDependentContext() ||
       RequireCompleteDeclContext(SS, DC))
-    return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
+    return ExprError();
 
   bool MemberOfUnknownSpecialization;
   LookupResult R(*this, NameInfo, LookupOrdinaryName);

Modified: cfe/trunk/test/SemaTemplate/instantiate-dependent-nested-name.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/instantiate-dependent-nested-name.cpp?rev=224451&r1=224450&r2=224451&view=diff
==============================================================================
--- cfe/trunk/test/SemaTemplate/instantiate-dependent-nested-name.cpp (original)
+++ cfe/trunk/test/SemaTemplate/instantiate-dependent-nested-name.cpp Wed Dec 17 13:34:15 2014
@@ -1,8 +1,19 @@
 // RUN: %clang_cc1 -fsyntax-only -verify %s
-// expected-no-diagnostics
+
 // PR4382
 template<typename T> struct X { static const T A = 1; };
 template<typename T, bool = X<T>::A> struct Y { typedef T A; };
 template<typename T> struct Z { typedef typename Y<T>::A A; };
 extern int x;
 extern Z<int>::A x;
+
+namespace pr21964 {
+struct H;
+template <class> struct T {
+  struct A; // expected-note {{member is declared here}}
+  static void B() {
+    A::template N<H>; // expected-error {{implicit instantiation of undefined member 'pr21964::T<pr21964::H>::A'}}
+  }
+};
+template struct T<H>; // expected-note {{requested here}}
+}