[libc] Define MB_LEN_MAX in limits.h
#102246
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Summary: This is supposed to define the maximum bytes required to store a char in any locale. There's some question about what this should be set to. I believe because the proposed solution for `locale.h` is to only support the default locale, we should do what `musl` does and set it to `4` which covers up to UTF-32. Fixes llvm#79358
jhuber6
requested review from
frobtech,
lntue,
michaelrj-google,
petrhosek and
SchrodingerZhu
|
@llvm/pr-subscribers-libc Author: Joseph Huber (jhuber6) ChangesSummary: Fixes #79358 Full diff: https://github.com/llvm/llvm-project/pull/102246.diff 1 Files Affected:
diff --git a/libc/include/llvm-libc-macros/limits-macros.h b/libc/include/llvm-libc-macros/limits-macros.h
index 456487e603b25..066896c73119f 100644
--- a/libc/include/llvm-libc-macros/limits-macros.h
+++ b/libc/include/llvm-libc-macros/limits-macros.h
@@ -19,12 +19,9 @@
#endif // __CHAR_BIT__
#endif // CHAR_BIT
-// TODO: https://github.com/llvm/llvm-project/issues/79358
-// Define MB_LEN_MAX if missing.
-// clang: MB_LEN_MAX = 1 -
-// https://github.com/llvm/llvm-project/blob/main/clang/lib/Headers/limits.h#L64
-// glibc: MB_LEN_MAX = 16 -
-// https://github.com/bminor/glibc/blob/master/include/limits.h#L32
+#ifndef MB_LEN_MAX
+#define MB_LEN_MAX 4
+#endif // MB_LEN_MAX
// *_WIDTH macros
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lntue
reviewed
Aug 7, 2024
| // glibc: MB_LEN_MAX = 16 - | ||
| // https://github.com/bminor/glibc/blob/master/include/limits.h#L32 | ||
| #ifndef MB_LEN_MAX | ||
| #define MB_LEN_MAX 4 |
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Do you mind adding comments about the rationale of the value, in case the assumption is changed in the future?
lntue
approved these changes
Aug 7, 2024
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Summary:
This is supposed to define the maximum bytes required to store a char in
any locale. There's some question about what this should be set to. I
believe because the proposed solution for
locale.his to only supportthe default locale, we should do what
musldoes and set it to4which covers up to UTF-32.
Fixes #79358