[c++20] Implement P0482R6: enable -fchar8_t by default in C++20 mode.
This unfortunately results in a substantial breaking change when
switching to C++20, but it's not yet clear what / how much we should
do about that. We may want to add a compatibility conversion from
u8 string literals to const char*, similar to how C++98 provided a
compatibility conversion from string literals to non-const char*,
but that's not handled by this patch.
The feature can be disabled in C++20 mode with -fno-char8_t.
llvm-svn: 346892
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 4a3195c..1ea3df4 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2475,7 +2475,7 @@
Opts.ImplicitModules = !Args.hasArg(OPT_fno_implicit_modules);
Opts.CharIsSigned = Opts.OpenCL || !Args.hasArg(OPT_fno_signed_char);
Opts.WChar = Opts.CPlusPlus && !Args.hasArg(OPT_fno_wchar);
- Opts.Char8 = Args.hasArg(OPT_fchar8__t);
+ Opts.Char8 = Args.hasFlag(OPT_fchar8__t, OPT_fno_char8__t, Opts.CPlusPlus2a);
if (const Arg *A = Args.getLastArg(OPT_fwchar_type_EQ)) {
Opts.WCharSize = llvm::StringSwitch<unsigned>(A->getValue())
.Case("char", 1)