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#if u8'\xff' != 0xff fails in the preprocessor unless -funsigned-char is specified #54886

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tbaederr opened this issue Apr 13, 2022 · 2 comments
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#if u8'\xff' != 0xff fails in the preprocessor unless -funsigned-char is specified #54886

tbaederr opened this issue Apr 13, 2022 · 2 comments
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clang:frontend Language frontend issues, e.g. anything involving "Sema"

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@tbaederr
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tbaederr commented Apr 13, 2022 •
edited by tahonermann
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From a discussion in https://reviews.llvm.org/D119221:

The following test case fails, unless -funsigned-char is specified; u8 character literals should always produce an unsigned char in C2x.

#if u8'\xff' != 0xff
#error uh oh
#endif

See also: https://godbolt.org/z/Tb7z85ToG
@tbaederr tbaederr added clang:frontend Language frontend issues, e.g. anything involving "Sema" and removed new issue labels Apr 13, 2022
@llvmbot
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llvmbot commented Apr 13, 2022

@llvm/issue-subscribers-clang-frontend

@tahonermann
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This is an issue for both C2x and C++17:

mem-frob pushed a commit to draperlaboratory/hope-llvm-project that referenced this issue Oct 7, 2022
@tbaederr
[clang][preprocessor] Fix unsigned-ness of utf8 char literals
d2d68f5 
UTF8 char literals are always unsigned.

Fixes llvm/llvm-project#54886

Differential Revision: https://reviews.llvm.org/D124996
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