Fix treatment of case which came up on std-proposals@: 'void' is permitted in core constant expressions, despite not being a literal type.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@164968 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 19 insertions, 3 deletions

diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index c4fd70a8c8..05912fc1c5 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -6196,11 +6196,9 @@ static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) {
       return false;
     Result = Info.CurrentCall->Temporaries[E];
   } else if (E->getType()->isVoidType()) {
-    if (Info.getLangOpts().CPlusPlus0x)
+    if (!Info.getLangOpts().CPlusPlus0x)
       Info.CCEDiag(E, diag::note_constexpr_nonliteral)
         << E->getType();
-    else
-      Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
     if (!EvaluateVoid(E, Info))
       return false;
   } else if (Info.getLangOpts().CPlusPlus0x) {
diff --git a/test/SemaCXX/constant-expression-cxx11.cpp b/test/SemaCXX/constant-expression-cxx11.cpp
index 930e70d4f3..065e396b15 100644
--- a/test/SemaCXX/constant-expression-cxx11.cpp
+++ b/test/SemaCXX/constant-expression-cxx11.cpp
@@ -1390,3 +1390,21 @@ namespace TLS {
   constexpr int *g() { return &m; }
   constexpr int *r = g();
 }
+
+namespace Void {
+  constexpr void f() { return; } // expected-error{{constexpr function's return type 'void' is not a literal type}}
+
+  void assert_failed(const char *msg, const char *file, int line); // expected-note {{declared here}}
+#define ASSERT(expr) ((expr) ? static_cast<void>(0) : assert_failed(#expr, __FILE__, __LINE__))
+  template<typename T, size_t S>
+  constexpr T get(T (&a)[S], size_t k) {
+    return ASSERT(k > 0 && k < S), a[k]; // expected-note{{non-constexpr function 'assert_failed'}}
+  }
+#undef ASSERT
+  template int get(int (&a)[4], size_t);
+  constexpr int arr[] = { 4, 1, 2, 3, 4 };
+  static_assert(get(arr, 1) == 1, "");
+  static_assert(get(arr, 4) == 4, "");
+  static_assert(get(arr, 0) == 4, ""); // expected-error{{not an integral constant expression}} \
+  // expected-note{{in call to 'get(arr, 0)'}}
+}