[3.13] gh-132026: Ensure _MIPS_SIM has defined _ABI identifiers for comparison (GH-132027) #133092
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…mparison (pythonGH-132027) When built on a MIPS architecture, `_MIPS_SIM` is used to determine architecture specifics. The value is expected to match either `_ABIO32`, `_ABIN32` or `_ABI64`. In `gcc` config/mips/mips.h these values are defined as compiler `builtin_define` inside of a switch/case. That means, mips64el and mips64 architectures know about `_ABI64` but don't know about `_ABIO32` and `_ABIN32`. In turn, when CPython tries to use them in comparison, they may be undefined identifiers. In default compiler behavior, the undefined identifier will be evaluated as zero, and it will not match `_MIPS_SIM`. However, the issues pop up when `-Wundef` (or, even worse, `-Werror=undef`) compiler flag is enabled. Then suddenly it's visible as a warning or error. (cherry picked from commit 6985e2e) Co-authored-by: Valters Jansons <sigv@users.noreply.github.com>
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This was referenced Apr 28, 2025
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When built on a MIPS architecture,
_MIPS_SIMis used to determinearchitecture specifics. The value is expected to match either
_ABIO32,_ABIN32or_ABI64.In
gccconfig/mips/mips.h these values are defined as compilerbuiltin_defineinside of a switch/case. That means, mips64el andmips64 architectures know about
_ABI64but don't know about_ABIO32and
_ABIN32. In turn, when CPython tries to use them in comparison,they may be undefined identifiers.
In default compiler behavior, the undefined identifier will be
evaluated as zero, and it will not match
_MIPS_SIM. However, theissues pop up when
-Wundef(or, even worse,-Werror=undef) compilerflag is enabled. Then suddenly it's visible as a warning or error.
(cherry picked from commit 6985e2e)
Co-authored-by: Valters Jansons sigv@users.noreply.github.com