[ADT] Make StringRef(const char*) constexpr

This should let us get rid of StringLiteral in the long term and avoid
chasing accidental StringRef globals once and for all.

This requires C++14, I godbolted it on every compiler I know we support
so I hope there won't be much fallout.

llvm-svn: 369961

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/unittests/ADT/StringRefTest.cpp b/llvm/unittests/ADT/StringRefTest.cpp
index f341cf4..c37ecf3 100644
--- a/llvm/unittests/ADT/StringRefTest.cpp
+++ b/llvm/unittests/ADT/StringRefTest.cpp
@@ -1050,6 +1050,10 @@ TEST(StringRefTest, DropWhileUntil) {
 }
 
 TEST(StringRefTest, StringLiteral) {
+  constexpr StringRef StringRefs[] = {"Foo", "Bar"};
+  EXPECT_EQ(StringRef("Foo"), StringRefs[0]);
+  EXPECT_EQ(StringRef("Bar"), StringRefs[1]);
+
   constexpr StringLiteral Strings[] = {"Foo", "Bar"};
   EXPECT_EQ(StringRef("Foo"), Strings[0]);
   EXPECT_EQ(StringRef("Bar"), Strings[1]);