Improve diagnostic to tell you a type is incomplete.

I recently ran into this code:
```
\#include <iostream>
void foo(const std::string &s, const std::string& = "");
\#include <string>
void test() { foo(""); }
```

The diagnostic produced said it can't bind char[1] to std::string
const&. It didn't mention std::string is incomplete. The user had to
infer that.

This patch causes the diagnostic to now say "incomplete type".

llvm-svn: 352927

2 files changed, 10 insertions, 1 deletions

diff --git a/clang/test/SemaCXX/cxx0x-initializer-stdinitializerlist.cpp b/clang/test/SemaCXX/cxx0x-initializer-stdinitializerlist.cpp
index f371891e548..9a82ec4a7bd 100644
--- a/clang/test/SemaCXX/cxx0x-initializer-stdinitializerlist.cpp
+++ b/clang/test/SemaCXX/cxx0x-initializer-stdinitializerlist.cpp
@@ -327,7 +327,7 @@ namespace update_rbrace_loc_crash {
   struct A {};
   template <typename T, typename F, int... I>
   std::initializer_list<T> ExplodeImpl(F p1, A<int, I...>) {
-    // expected-error@+1 {{reference to type 'const update_rbrace_loc_crash::Incomplete' could not bind to an rvalue of type 'void'}}
+    // expected-error@+1 {{reference to incomplete type 'const update_rbrace_loc_crash::Incomplete' could not bind to an rvalue of type 'void'}}
     return {p1(I)...};
   }
   template <typename T, int N, typename F>
diff --git a/clang/test/SemaCXX/decl-init-ref.cpp b/clang/test/SemaCXX/decl-init-ref.cpp
index 42b9286852c..fb5ca8c1491 100644
--- a/clang/test/SemaCXX/decl-init-ref.cpp
+++ b/clang/test/SemaCXX/decl-init-ref.cpp
@@ -36,3 +36,12 @@ namespace PR16502 {
   int f();
   const A &c = { 10, ++c.temporary };
 }
+
+namespace IncompleteTest {
+  struct String;
+  // expected-error@+1 {{reference to incomplete type 'const IncompleteTest::String' could not bind to an lvalue of type 'const char [1]'}}
+  void takeString(const String& = "") {} // expected-note {{passing argument to parameter here}} expected-note {{candidate function}}
+  void test() {
+        takeString(); // expected-error {{no matching function for call}}
+  }
+}