constexpr: semantic checking for constexpr variables.

We had an extension which allowed const static class members of floating-point type to have in-class initializers, 'as a C++0x extension'. However, C++0x does not allow this. The extension has been kept, and extended to all literal types in C++0x mode (with a fixit to add the 'constexpr' specifier).

llvm-svn: 140801
diff --git a/clang/test/CXX/class/class.static/class.static.data/p3.cpp b/clang/test/CXX/class/class.static/class.static.data/p3.cpp
new file mode 100644
index 0000000..72dbec7
--- /dev/null
+++ b/clang/test/CXX/class/class.static/class.static.data/p3.cpp
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++0x %s
+
+struct NonLit {
+  NonLit();
+};
+
+struct S {
+  static constexpr int a = 0;
+  static constexpr int b; // expected-error {{declaration of constexpr variable 'b' requires an initializer}}
+
+  static constexpr int c = 0;
+  static const int d;
+
+  static constexpr double e = 0.0; // ok
+  static const double f = 0.0; // expected-warning {{accepted as an extension}}
+  static char *const g = 0; // expected-warning {{accepted as an extension}}
+  static const NonLit h = NonLit(); // expected-error {{must be initialized out of line}}
+};
+
+constexpr int S::a; // expected-error {{definition of initialized static data member 'a' cannot be marked constexpr}}
+constexpr int S::b = 0;
+
+const int S::c;
+constexpr int S::d = 0;