Bug#945133: gcc-9: __has_attribute(ifunc) false positive on hurd and kfreebsd

[Fabian Klötzl]

Hi Samuel,

I forwarded the bug to the GCC tracker and they said that your 
interpretation of the docs is correct. I doubt whether they are willing 
to change the behaviour, but we'll see.


Best,
Fabian

Processed: Re: Bug#945133: gcc-9: __has_attribute(ifunc) false positive on hurd and kfreebsd

[Debian Bug Tracking System]

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> forwarded 945133 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93419
Bug #945133 [gcc-9] gcc-9: __has_attribute(ifunc) false positive on hurd and 
kfreebsd
Set Bug forwarded-to-address to 
'https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93419'.
>
End of message, stopping processing here.

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945133: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=945133
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Bug#945133: gcc-9: __has_attribute(ifunc) false positive on hurd and kfreebsd

[Fabian Klötzl]

forwarded 945133 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93419

Bug#945133: gcc-9: __has_attribute(ifunc) false positive on hurd and kfreebsd

[Samuel Thibault]

Hello,

On 20.11.19 11:43, Fabian Kloetzl wrote:
> Recently, the build of one of my packages failed on hurd-i386 and
> kfreebsd-* due to unsupported ifuncs [1]. However, I had that code guarded
> by __has_attribute(ifunc) which, unfortunately, evaluates to 1 on said
> platforms. A minimal testcase is attached.

AIUI, that is expected by gcc people: the gcc documentation says:

“to test whether the attribute referenced by its operand is recognized
by GCC”

Strictly speaking, being recognized by GCC doesn't mean being supported
on the target platform. I agree that it makes it not really useful
here, but I'm not the one to be convinced :) I'd say bring the issue to
upstream gcc.

Samuel

Bug#945133: gcc-9: __has_attribute(ifunc) false positive on hurd and kfreebsd

[Matthias Klose]

Forwarded ...

On 20.11.19 11:43, Fabian Kloetzl wrote:
> Package: gcc-9
> Version: 9.2.1-17
> Severity: normal
> 
> Dear Maintainer,
> 
> Recently, the build of one of my packages failed on hurd-i386 and
> kfreebsd-* due to unsupported ifuncs [1]. However, I had that code guarded
> by __has_attribute(ifunc) which, unfortunately, evaluates to 1 on said
> platforms. A minimal testcase is attached.
> 
> Best,
> Fabian
> 
> 1: https://buildd.debian.org/status/package.php?p=phylonium
> 

Bug#945133: gcc-9: __has_attribute(ifunc) false positive on hurd and kfreebsd

[Fabian Kloetzl]

Package: gcc-9
Version: 9.2.1-17
Severity: normal

Dear Maintainer,

Recently, the build of one of my packages failed on hurd-i386 and
kfreebsd-* due to unsupported ifuncs [1]. However, I had that code guarded
by __has_attribute(ifunc) which, unfortunately, evaluates to 1 on said
platforms. A minimal testcase is attached.

Best,
Fabian

1: https://buildd.debian.org/status/package.php?p=phylonium
#include 

int main() {
return 0;
}

#if __has_attribute(ifunc)

typedef void (fntype)(void);
fntype* fn_select(void) {
return NULL;
}

void fn(void) __attribute__((ifunc("fn_select")));

#endif