tahonermann added inline comments.
================
Comment at: clang/test/Lexer/utf8-char-literal.cpp:54-56
+# if !(u8'\xff' == 0xff)
+# error u8 char literal is not unsigned
+# endif
----------------
tbaeder wrote:
> tahonermann wrote:
> > The C++ case looks good now, but the condition doesn't look right for the C
> > case. The expectation is that `u8'\xff'` should not match `'\xff'` in C23
> > mode, but the test treats this as an error. If the test is passing, that
> > indicates something is not being validated correctly. Shouldn't unexpected
> > error diagnostics cause the test to fail?
> I used `u8'\xff' != 0xff` here because that's the condition you mentioned in
> the phab review adding the `u8` prefix. Using `u8'\xff' != '\xff'` indeed
> fails with:
>
> ```
> clang/test/Lexer/utf8-char-literal.cpp Line 55: u8 char literal is not
> unsigned
> clang/test/Lexer/utf8-char-literal.cpp Line 54: right side of operator
> converted from negative value to unsigned: -1 to 18446744073709551615
> ```
Oh! I missed the use of `0xff` vs `'\xff'`. Sorry if I mislead you. In order to
avoid such subtle differences in the test, can we use the same check as for C++?
// UTF-8 character literals are enabled in C23 and later and are always
unsigned.
#if __STDC_VERSION__ >= 202000L
# if u8'\xff' == '\xff' // expected-warning {{right side of operator
converted from negative value to unsigned}}
# error UTF-8 character value matched ordinary character literal; this is
unexpected
# endif
#endif
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D124996/new/
https://reviews.llvm.org/D124996
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