Implement P0482R2, support for char8_t type.

This is not yet part of any C++ working draft, and so is controlled by the flag
-fchar8_t rather than a -std= flag. (The GCC implementation is controlled by a
flag with the same name.)

This implementation is experimental, and will be removed or revised
substantially to match the proposal as it makes its way through the C++
committee.

llvm-svn: 331244

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 192862db657..8a87b9f35e3 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -559,6 +559,10 @@ static void InitializeCPlusPlusFeatureTestMacros(const LangOptions &LangOpts,
     Builder.defineMacro("__cpp_experimental_concepts", "1");
   if (LangOpts.CoroutinesTS)
     Builder.defineMacro("__cpp_coroutines", "201703L");
+
+  // Potential future breaking changes.
+  if (LangOpts.Char8)
+    Builder.defineMacro("__cpp_char8_t", "201803");
 }
 
 static void InitializePredefinedMacros(const TargetInfo &TI,
@@ -939,6 +943,8 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
                                        InlineWidthBits));
     DEFINE_LOCK_FREE_MACRO(BOOL, Bool);
     DEFINE_LOCK_FREE_MACRO(CHAR, Char);
+    if (LangOpts.Char8)
+      DEFINE_LOCK_FREE_MACRO(CHAR8_T, Char); // Treat char8_t like char.
     DEFINE_LOCK_FREE_MACRO(CHAR16_T, Char16);
     DEFINE_LOCK_FREE_MACRO(CHAR32_T, Char32);
     DEFINE_LOCK_FREE_MACRO(WCHAR_T, WChar);