rtld, libthr: Use nonstring attribute to silence compiler warning
#1882
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Ericson2314
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llvm/llvm-project#137705 ah interesting, it is an old GCC feature, but new in Clang. I will add some CPP compat magic for this accordingly. |
With Clang 21 at least, we start to get warnings like:
```
rtld.c:333:58: error: initializer-string for character array is too long, array size is 4 but initializer has size 5 (including the null terminating character); did you mean to use the 'nonstring' attribute? [-Werror,-Wunterminated-string-initialization]
333 | static const char rtld_utrace_sig[RTLD_UTRACE_SIG_SZ] = RTLD_UTRACE_SIG;
| ^~~~~~~~~~~~~~~
./rtld_utrace.h:49:27: note: expanded from macro 'RTLD_UTRACE_SIG'
49 | #define RTLD_UTRACE_SIG "RTLD"
|
```
Looking up the `nonstring` attribute [1], it does seem to be the correct
thing --- indicating a char array which should not have a null
terminator byte --- to use in these two cases.
Note: I discovered this when fixing Nixpkgs's FreeBSD cross compilation
support. I understand that FreeBSD may not officially support this
version of Clang yet, and so the CPP that is needed is a bit annoying.
But it still hopefully will make things easier once it comes time to
bump the supported version of Clang to one with this attribute.
I am hoping thus that this patch is acceptable, as just early readiness
for when FreeBSD does upgrade to that version of Clang.
[1]: https://clang.llvm.org/docs/AttributeReference.html#nonstring
Signed-off-by: John Ericson <[email protected]>
Ericson2314
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OK this only uses the attribute when it exists, now. |
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It looks like upgrading to newer clang has caused some `-Werror` problems. We should probably disable `-Werror` entirely, but for now, I've done the more targetted fix of disabling one specific warning, and sending freebsd/freebsd-src#1882 upstream.
Member
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Thank you, but I think #1847 should cover this. |
Author
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Ah ok good that exists. Hope it is merged soon. |
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With Clang 21 at least, we start to get warnings like:
Looking up the
nonstringattribute 1, it does seem to be the correct thing --- indicating a char array which should not have a null terminator byte --- to use in these two cases.Note: I discovered this when fixing Nixpkgs's FreeBSD cross compilation support. I understand that FreeBSD may not officially support this version of Clang yet, but I am hoping the attribute still works with the version of Clang it does support (even if it not yet needed on that version to fix
-Werrorerrors). I am hoping thus that this patch is accessible, as just early readiness for when FreeBSD does upgrade to that version of Clang.