[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/test/SemaCXX/char8_t.cpp b/clang/test/SemaCXX/char8_t.cpp
index 5eb3d70..f60a66d 100644
--- a/clang/test/SemaCXX/char8_t.cpp
+++ b/clang/test/SemaCXX/char8_t.cpp
@@ -1,4 +1,5 @@
-// RUN: %clang_cc1 -fchar8_t -std=c++2a -verify %s
+// RUN: %clang_cc1 -fchar8_t -std=c++17 -verify %s
+// RUN: %clang_cc1 -std=c++2a -verify %s
char8_t a = u8'a';
char8_t b[] = u8"foo";
@@ -6,7 +7,12 @@
char8_t d[] = "foo"; // expected-error {{initializing 'char8_t' array with plain string literal}} expected-note {{add 'u8' prefix}}
char e = u8'a';
-char f[] = u8"foo"; // expected-error {{initialization of char array with UTF-8 string literal is not permitted by '-fchar8_t'}}
+char f[] = u8"foo";
+#if __cplusplus <= 201703L
+// expected-error@-2 {{initialization of char array with UTF-8 string literal is not permitted by '-fchar8_t'}}
+#else
+// expected-error@-4 {{ISO C++20 does not permit initialization of char array with UTF-8 string literal}}
+#endif
char g = 'a';
char h[] = "foo";