* [musl] [PATCH v2] prevent from redefining __STDC_UTF_{16,32}__ macros @ 2024-01-25 14:14 Jules Maselbas 2024-02-26 2:17 ` Rich Felker 0 siblings, 1 reply; 5+ messages in thread From: Jules Maselbas @ 2024-01-25 14:14 UTC (permalink / raw) To: musl; +Cc: Jules Maselbas Undefine any previous __STDC_UTF_{16,32}__ macros before defining them to prenvent any warnings of redefining macros. --- v2: - changed `#if !define(...)` guard to `#undef`, as suggested by Rich Felker I encountered this "issue" trying to compile a program with the -isystem option to override toolchain/installed musl headers with one from source. include/stdc-predef.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/include/stdc-predef.h b/include/stdc-predef.h index af1a2799..5ccd884d 100644 --- a/include/stdc-predef.h +++ b/include/stdc-predef.h @@ -7,7 +7,10 @@ #define __STDC_IEC_559__ 1 #endif +#undef __STDC_UTF_16__ #define __STDC_UTF_16__ 1 + +#undef __STDC_UTF_32__ #define __STDC_UTF_32__ 1 #endif -- 2.43.0 ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [musl] [PATCH v2] prevent from redefining __STDC_UTF_{16,32}__ macros 2024-01-25 14:14 [musl] [PATCH v2] prevent from redefining __STDC_UTF_{16,32}__ macros Jules Maselbas @ 2024-02-26 2:17 ` Rich Felker 2024-02-26 3:47 ` Gabriel Ravier 0 siblings, 1 reply; 5+ messages in thread From: Rich Felker @ 2024-02-26 2:17 UTC (permalink / raw) To: Jules Maselbas; +Cc: musl On Thu, Jan 25, 2024 at 03:14:40PM +0100, Jules Maselbas wrote: > Undefine any previous __STDC_UTF_{16,32}__ macros before defining > them to prenvent any warnings of redefining macros. > > --- > v2: > - changed `#if !define(...)` guard to `#undef`, as suggested by Rich Felker > > I encountered this "issue" trying to compile a program with the -isystem > option to override toolchain/installed musl headers with one from source. > > include/stdc-predef.h | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/include/stdc-predef.h b/include/stdc-predef.h > index af1a2799..5ccd884d 100644 > --- a/include/stdc-predef.h > +++ b/include/stdc-predef.h > @@ -7,7 +7,10 @@ > #define __STDC_IEC_559__ 1 > #endif > > +#undef __STDC_UTF_16__ > #define __STDC_UTF_16__ 1 > + > +#undef __STDC_UTF_32__ > #define __STDC_UTF_32__ 1 > > #endif > -- > 2.43.0 I merged this, but now gcc warns about undefining them if system header warnings aren't suppressed. I'm not sure what the justification is for that... *sigh* Rich ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [musl] [PATCH v2] prevent from redefining __STDC_UTF_{16,32}__ macros 2024-02-26 2:17 ` Rich Felker @ 2024-02-26 3:47 ` Gabriel Ravier 2024-02-26 7:14 ` Jens Gustedt 0 siblings, 1 reply; 5+ messages in thread From: Gabriel Ravier @ 2024-02-26 3:47 UTC (permalink / raw) To: musl, Rich Felker, Jules Maselbas On 2/26/24 02:17, Rich Felker wrote: > On Thu, Jan 25, 2024 at 03:14:40PM +0100, Jules Maselbas wrote: >> Undefine any previous __STDC_UTF_{16,32}__ macros before defining >> them to prenvent any warnings of redefining macros. >> >> --- >> v2: >> - changed `#if !define(...)` guard to `#undef`, as suggested by Rich Felker >> >> I encountered this "issue" trying to compile a program with the -isystem >> option to override toolchain/installed musl headers with one from source. >> >> include/stdc-predef.h | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/include/stdc-predef.h b/include/stdc-predef.h >> index af1a2799..5ccd884d 100644 >> --- a/include/stdc-predef.h >> +++ b/include/stdc-predef.h >> @@ -7,7 +7,10 @@ >> #define __STDC_IEC_559__ 1 >> #endif >> >> +#undef __STDC_UTF_16__ >> #define __STDC_UTF_16__ 1 >> + >> +#undef __STDC_UTF_32__ >> #define __STDC_UTF_32__ 1 >> >> #endif >> -- >> 2.43.0 > I merged this, but now gcc warns about undefining them if system > header warnings aren't suppressed. I'm not sure what the justification > is for that... *sigh* > > Rich It appears as though since 2001 GCC makes it so that any redefinition or undefinition of any macro with a name starting with "__STDC_" (with hard-coded exceptions for __STDC_FORMAT_MACROS, __STDC_LIMIT_MACROS and __STDC_CONSTANT_MACROS) always results in a warning (from reading the code this doesn't seem to be tied to any -W switch, so it's simply entirely impossible to work around) ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [musl] [PATCH v2] prevent from redefining __STDC_UTF_{16,32}__ macros 2024-02-26 3:47 ` Gabriel Ravier @ 2024-02-26 7:14 ` Jens Gustedt 2024-02-26 14:36 ` Rich Felker 0 siblings, 1 reply; 5+ messages in thread From: Jens Gustedt @ 2024-02-26 7:14 UTC (permalink / raw) To: musl, Gabriel Ravier, Rich Felker, Jules Maselbas Hi Am 26. Februar 2024 04:47:22 MEZ schrieb Gabriel Ravier <gabravier@gmail.com>: > On 2/26/24 02:17, Rich Felker wrote: > > On Thu, Jan 25, 2024 at 03:14:40PM +0100, Jules Maselbas wrote: > >> Undefine any previous __STDC_UTF_{16,32}__ macros before defining > >> them to prenvent any warnings of redefining macros. > >> > >> --- > >> v2: > >> - changed `#if !define(...)` guard to `#undef`, as suggested by Rich Felker > >> > >> I encountered this "issue" trying to compile a program with the -isystem > >> option to override toolchain/installed musl headers with one from source. > >> > >> include/stdc-predef.h | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/include/stdc-predef.h b/include/stdc-predef.h > >> index af1a2799..5ccd884d 100644 > >> --- a/include/stdc-predef.h > >> +++ b/include/stdc-predef.h > >> @@ -7,7 +7,10 @@ > >> #define __STDC_IEC_559__ 1 > >> #endif > >> +#undef __STDC_UTF_16__ > >> #define __STDC_UTF_16__ 1 > >> + > >> +#undef __STDC_UTF_32__ > >> #define __STDC_UTF_32__ 1 > >> #endif > >> -- > >> 2.43.0 > > I merged this, but now gcc warns about undefining them if system > > header warnings aren't suppressed. I'm not sure what the justification > > is for that... *sigh* > > > > Rich > > It appears as though since 2001 GCC makes it so that any redefinition or undefinition of any macro with a name starting with "__STDC_" (with hard-coded exceptions for __STDC_FORMAT_MACROS, __STDC_LIMIT_MACROS and __STDC_CONSTANT_MACROS) always results in a warning (from reading the code this doesn't seem to be tied to any -W switch, so it's simply entirely impossible to work around) > The way to go would be to #ifdef them, not to use #undef. These are really a language feature and not library, so anything that this should do is repair work for older compilers. The compiler's setting, if any, should prime over the C library. With C23 these two macros become mandatory. Jens -- Jens Gustedt - INRIA & ICube, Strasbourg, France ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [musl] [PATCH v2] prevent from redefining __STDC_UTF_{16,32}__ macros 2024-02-26 7:14 ` Jens Gustedt @ 2024-02-26 14:36 ` Rich Felker 0 siblings, 0 replies; 5+ messages in thread From: Rich Felker @ 2024-02-26 14:36 UTC (permalink / raw) To: Jens Gustedt; +Cc: musl, Gabriel Ravier, Jules Maselbas On Mon, Feb 26, 2024 at 08:14:52AM +0100, Jens Gustedt wrote: > Hi > > Am 26. Februar 2024 04:47:22 MEZ schrieb Gabriel Ravier <gabravier@gmail.com>: > > On 2/26/24 02:17, Rich Felker wrote: > > > On Thu, Jan 25, 2024 at 03:14:40PM +0100, Jules Maselbas wrote: > > >> Undefine any previous __STDC_UTF_{16,32}__ macros before defining > > >> them to prenvent any warnings of redefining macros. > > >> > > >> --- > > >> v2: > > >> - changed `#if !define(...)` guard to `#undef`, as suggested by Rich Felker > > >> > > >> I encountered this "issue" trying to compile a program with the -isystem > > >> option to override toolchain/installed musl headers with one from source. > > >> > > >> include/stdc-predef.h | 3 +++ > > >> 1 file changed, 3 insertions(+) > > >> > > >> diff --git a/include/stdc-predef.h b/include/stdc-predef.h > > >> index af1a2799..5ccd884d 100644 > > >> --- a/include/stdc-predef.h > > >> +++ b/include/stdc-predef.h > > >> @@ -7,7 +7,10 @@ > > >> #define __STDC_IEC_559__ 1 > > >> #endif > > >> +#undef __STDC_UTF_16__ > > >> #define __STDC_UTF_16__ 1 > > >> + > > >> +#undef __STDC_UTF_32__ > > >> #define __STDC_UTF_32__ 1 > > >> #endif > > >> -- > > >> 2.43.0 > > > I merged this, but now gcc warns about undefining them if system > > > header warnings aren't suppressed. I'm not sure what the justification > > > is for that... *sigh* > > > > > > Rich > > > > It appears as though since 2001 GCC makes it so that any > > redefinition or undefinition of any macro with a name starting > > with "__STDC_" (with hard-coded exceptions for > > __STDC_FORMAT_MACROS, __STDC_LIMIT_MACROS and > > __STDC_CONSTANT_MACROS) always results in a warning (from reading > > the code this doesn't seem to be tied to any -W switch, so it's > > simply entirely impossible to work around) > > > > The way to go would be to #ifdef them, not to use #undef. > These are really a language feature and not library, so anything > that this should do is repair work for older compilers. The > compiler's setting, if any, should prime over the C library. > > With C23 these two macros become mandatory. I think the gcc folks originally saw them as library-dependent, maybe because of the char16_t/char32_t library functions. This is why we had to define them ourselves in the first place. However indeed they are a matter of how the compiler translates literals. I'm okay with just switching to the original patch with #ifndef. But it's probably unfortunate that gcc is this aggressive about the issue. Rich ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2024-02-26 14:36 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2024-01-25 14:14 [musl] [PATCH v2] prevent from redefining __STDC_UTF_{16,32}__ macros Jules Maselbas 2024-02-26 2:17 ` Rich Felker 2024-02-26 3:47 ` Gabriel Ravier 2024-02-26 7:14 ` Jens Gustedt 2024-02-26 14:36 ` Rich Felker
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