diff mbox series

linux: Fix a non-constant expression in _Static_assert

Message ID 20210926223619.552849-1-maskray@google.com
State Committed
Headers show
Series linux: Fix a non-constant expression in _Static_assert | expand

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Commit Message

Fāng-ruì Sòng Sept. 26, 2021, 10:36 p.m. UTC
According to C11 6.6p6, `const int` as an operand does not make up a
constant expression. Clang reports an error and GCC reports an error
if fed into the preprocessed output:

../sysdeps/unix/sysv/linux/opendir.c:107:19: error: static_assert expression is not an integral constant expression
  _Static_assert (allocation_size >= sizeof (struct dirent64),

GCC accepting the unpreprocessed source is a bug.

Fixes: 4b962c9e859de23b461d61f860dbd3f21311e83a ("linux: Simplify opendir buffer allocation")
---
 sysdeps/unix/sysv/linux/opendir.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Paul Eggert Sept. 26, 2021, 10:58 p.m. UTC | #1
On 9/26/21 3:36 PM, Fangrui Song via Libc-alpha wrote:
> diff --git a/sysdeps/unix/sysv/linux/opendir.c b/sysdeps/unix/sysv/linux/opendir.c
...
> -  const size_t allocation_size = 32768;
> +  enum { allocation_size = 32768 };

Thanks, this is obviously a good fix. It's the usual way I fix this sort 
of thing, for values that must fit in 'int' range which this one does.
Fāng-ruì Sòng Sept. 26, 2021, 11:25 p.m. UTC | #2
On 2021-09-26, Fangrui Song wrote:
>According to C11 6.6p6, `const int` as an operand does not make up a
>constant expression. Clang reports an error and GCC reports an error
>if fed into the preprocessed output:
>
>../sysdeps/unix/sysv/linux/opendir.c:107:19: error: static_assert expression is not an integral constant expression
>  _Static_assert (allocation_size >= sizeof (struct dirent64),
>
>GCC accepting the unpreprocessed source is a bug.
>
>Fixes: 4b962c9e859de23b461d61f860dbd3f21311e83a ("linux: Simplify opendir buffer allocation")
>---
> sysdeps/unix/sysv/linux/opendir.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/sysdeps/unix/sysv/linux/opendir.c b/sysdeps/unix/sysv/linux/opendir.c
>index 48f254d169..88640f44ee 100644
>--- a/sysdeps/unix/sysv/linux/opendir.c
>+++ b/sysdeps/unix/sysv/linux/opendir.c
>@@ -103,7 +103,7 @@ __alloc_dir (int fd, bool close_fd, int flags,
>      file system provides a bogus value.  */
>   enum { max_buffer_size = 1048576 };
>
>-  const size_t allocation_size = 32768;
>+  enum { allocation_size = 32768 };
>   _Static_assert (allocation_size >= sizeof (struct dirent64),
> 		  "allocation_size < sizeof (struct dirent64)");
>
>-- 
>2.33.0.685.g46640cef36-goog

The description needs some adjustment
https://www.iso-9899.info/n1570.html#6.6p10

10   An implementation may accept other forms of constant expressions.

gcc accepting `const int` is fine as an extension point, but having different behaviors under -O0 and -O2 is not great.

   #include <stddef.h>
   int main() {
     const size_t size = 32768;
     struct A {int a;};
     _Static_assert (size >= sizeof (struct A), "");
   }

% gcc -c a.c -O2  # no error
% gcc -c a.c -O0
a.c: In function ‘main’:
a.c:5:24: error: expression in static assertion is not constant
     5 |   _Static_assert (size >= sizeof (struct A), "");
       |
Florian Weimer Sept. 27, 2021, 1:08 p.m. UTC | #3
* Paul Eggert:

> On 9/26/21 3:36 PM, Fangrui Song via Libc-alpha wrote:
>> diff --git a/sysdeps/unix/sysv/linux/opendir.c b/sysdeps/unix/sysv/linux/opendir.c
> ...
>> -  const size_t allocation_size = 32768;
>> +  enum { allocation_size = 32768 };
>
> Thanks, this is obviously a good fix. It's the usual way I fix this
> sort of thing, for values that must fit in 'int' range which this one
> does.

I think GCC supports this for all integer types as an extension.

Thanks,
Florian
Florian Weimer Sept. 27, 2021, 1:08 p.m. UTC | #4
* Fangrui Song via Libc-alpha:

> The description needs some adjustment
> https://www.iso-9899.info/n1570.html#6.6p10
>
> 10   An implementation may accept other forms of constant expressions.

Yeah, but the change itself is clearly correct.  Thanks.

Florian
Fāng-ruì Sòng Sept. 27, 2021, 5:17 p.m. UTC | #5
On Mon, Sep 27, 2021 at 6:09 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> * Fangrui Song via Libc-alpha:
>
> > The description needs some adjustment
> > https://www.iso-9899.info/n1570.html#6.6p10
> >
> > 10   An implementation may accept other forms of constant expressions.
>
> Yeah, but the change itself is clearly correct.  Thanks.
>
> Florian
>

Ugh, you may have missed my point that GCC -O0 and -O2 are not
consistent on whether a `const int` operand can be used in a constant
expression.

Updated description:

---

linux: Fix a non-constant expression in _Static_assert

According to C11 6.6p6, `const int` as an operand may not make up a
constant expression. GCC's -O0 and -O2 optimization levels are not
consistent on whether this operand can be used in a constant expression:

../sysdeps/unix/sysv/linux/opendir.c:107:19: error: static_assert
expression is not an integral constant expression
  _Static_assert (allocation_size >= sizeof (struct dirent64),

Use enum which is guaranteed to be a constant expression.
This fixes an error when compiling with GCC -O0 and Clang.

Fixes: 4b962c9e859de23b461d61f860dbd3f21311e83a ("linux: Simplify
opendir buffer allocation")
Andrew Pinski Sept. 27, 2021, 6 p.m. UTC | #6
On Mon, Sep 27, 2021 at 10:18 AM Fāng-ruì Sòng via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> On Mon, Sep 27, 2021 at 6:09 AM Florian Weimer <fweimer@redhat.com> wrote:
> >
> > * Fangrui Song via Libc-alpha:
> >
> > > The description needs some adjustment
> > > https://www.iso-9899.info/n1570.html#6.6p10
> > >
> > > 10   An implementation may accept other forms of constant expressions.
> >
> > Yeah, but the change itself is clearly correct.  Thanks.
> >
> > Florian
> >
>
> Ugh, you may have missed my point that GCC -O0 and -O2 are not
> consistent on whether a `const int` operand can be used in a constant
> expression.

Yes and that was fixed for GCC 8 by r8-4755.
Since you were not specific on which version of GCC, I am assuming it
was GCC7.x.

Thanks,
Andrew Pinski

>
> Updated description:
>
> ---
>
> linux: Fix a non-constant expression in _Static_assert
>
> According to C11 6.6p6, `const int` as an operand may not make up a
> constant expression. GCC's -O0 and -O2 optimization levels are not
> consistent on whether this operand can be used in a constant expression:
>
> ../sysdeps/unix/sysv/linux/opendir.c:107:19: error: static_assert
> expression is not an integral constant expression
>   _Static_assert (allocation_size >= sizeof (struct dirent64),
>
> Use enum which is guaranteed to be a constant expression.
> This fixes an error when compiling with GCC -O0 and Clang.
>
> Fixes: 4b962c9e859de23b461d61f860dbd3f21311e83a ("linux: Simplify
> opendir buffer allocation")
Fāng-ruì Sòng Sept. 27, 2021, 6:20 p.m. UTC | #7
On 2021-09-27, Andrew Pinski wrote:
>On Mon, Sep 27, 2021 at 10:18 AM Fāng-ruì Sòng via Libc-alpha
><libc-alpha@sourceware.org> wrote:
>>
>> On Mon, Sep 27, 2021 at 6:09 AM Florian Weimer <fweimer@redhat.com> wrote:
>> >
>> > * Fangrui Song via Libc-alpha:
>> >
>> > > The description needs some adjustment
>> > > https://www.iso-9899.info/n1570.html#6.6p10
>> > >
>> > > 10   An implementation may accept other forms of constant expressions.
>> >
>> > Yeah, but the change itself is clearly correct.  Thanks.
>> >
>> > Florian
>> >
>>
>> Ugh, you may have missed my point that GCC -O0 and -O2 are not
>> consistent on whether a `const int` operand can be used in a constant
>> expression.
>
>Yes and that was fixed for GCC 8 by r8-4755.
>Since you were not specific on which version of GCC, I am assuming it
>was GCC7.x.
>
>Thanks,
>Andrew Pinski

Sorry for the imprecise description.
I think the issue is different from your mentioned GCC 8 bugfix.

I commented out these lines in include/libc-symbols.h

-#if !defined __ASSEMBLER__ && !defined __OPTIMIZE__
-# error "glibc cannot be compiled without optimization"
-#endif
+//#if !defined __ASSEMBLER__ && !defined __OPTIMIZE__
+//# error "glibc cannot be compiled without optimization"
+//#endif

Next,

a=(../sysdeps/unix/sysv/linux/dl-opendir.c -std=gnu11 -fgnu89-inline -g -Wall -Wwrite-strings -Wundef -fmerge-all-constants -frounding-math -fno-stack-protector -fno-common -Wstrict-prototypes -Wold-style-definition -fmath-errno -fPIC -fno-stack-protector -DSTACK_PROTECTOR_LEVEL=0 -mno-mmx -ftls-model=initial-exec -I../include -I$HOME/Dev/glibc/out/clang/elf -I$HOME/Dev/glibc/out/clang -I../sysdeps/unix/sysv/linux/x86_64/64 -I../sysdeps/unix/sysv/linux/x86_64 -I../sysdeps/unix/sysv/linux/x86/include -I../sysdeps/unix/sysv/linux/x86 -I../sysdeps/x86/nptl -I../sysdeps/unix/sysv/linux/wordsize-64 -I../sysdeps/x86_64/nptl -I../sysdeps/unix/sysv/linux/include -I../sysdeps/unix/sysv/linux -I../sysdeps/nptl -I../sysdeps/pthread -I../sysdeps/gnu -I../sysdeps/unix/inet -I../sysdeps/unix/sysv -I../sysdeps/unix/x86_64 -I../sysdeps/unix -I../sysdeps/posix -I../sysdeps/x86_64/64 -I../sysdeps/x86_64/fpu/multiarch -I../sysdeps/x86_64/fpu -I../sysdeps/x86/fpu -I../sysdeps/x86_64/multiarch -I../sysdeps/x86_64 -I../sysdeps/x86/include -I../sysdeps/x86 -I../sysdeps/ieee754/float128 -I../sysdeps/ieee754/ldbl-96/include -I../sysdeps/ieee754/ldbl-96 -I../sysdeps/ieee754/dbl-64 -I../sysdeps/ieee754/flt-32 -I../sysdeps/wordsize-64 -I../sysdeps/ieee754 -I../sysdeps/generic -I.. -I../libio -I. -D_LIBC_REENTRANT -include $HOME/Dev/glibc/out/clang/libc-modules.h -include ../include/libc-symbols.h -DPIC -DSHARED -DTOP_NAMESPACE=glibc -fsyntax-only)

% gcc-11 $=a -O2  # good
% gcc-11 $=a -O0  # -O1 is similar
In file included from ../include/features.h:488,
                  from ../posix/sys/types.h:25,
                  from ../include/sys/types.h:1,
                  from ../sysdeps/unix/sysv/linux/dirstream.h:21,
                  from ../include/dirent.h:3,
                  from ../sysdeps/unix/sysv/linux/opendir.c:18,
                  from ../sysdeps/unix/sysv/linux/dl-opendir.c:1:
../sysdeps/unix/sysv/linux/opendir.c: In function ‘__alloc_dir’:
../sysdeps/unix/sysv/linux/opendir.c:107:35: error: expression in static assertion is not constant
   107 |   _Static_assert (allocation_size >= sizeof (struct dirent64),
       |                   ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
../include/sys/cdefs.h:7:59: note: in definition of macro ‘_Static_assert’
     7 | # define _Static_assert(expr, diagnostic) _Static_assert (expr, diagnostic)
       |                                                           ^~~~

Then I tested gcc-8, gcc-9, gcc-10 on Debian testing, they have the same behavior as gcc-11.

>>
>> Updated description:
>>
>> ---
>>
>> linux: Fix a non-constant expression in _Static_assert
>>
>> According to C11 6.6p6, `const int` as an operand may not make up a
>> constant expression. GCC's -O0 and -O2 optimization levels are not
>> consistent on whether this operand can be used in a constant expression:
>>
>> ../sysdeps/unix/sysv/linux/opendir.c:107:19: error: static_assert
>> expression is not an integral constant expression
>>   _Static_assert (allocation_size >= sizeof (struct dirent64),
>>
>> Use enum which is guaranteed to be a constant expression.
>> This fixes an error when compiling with GCC -O0 and Clang.
>>
>> Fixes: 4b962c9e859de23b461d61f860dbd3f21311e83a ("linux: Simplify
>> opendir buffer allocation")
Andrew Pinski Sept. 27, 2021, 6:21 p.m. UTC | #8
On Mon, Sep 27, 2021 at 11:20 AM Fāng-ruì Sòng <maskray@google.com> wrote:
>
>
> On 2021-09-27, Andrew Pinski wrote:
> >On Mon, Sep 27, 2021 at 10:18 AM Fāng-ruì Sòng via Libc-alpha
> ><libc-alpha@sourceware.org> wrote:
> >>
> >> On Mon, Sep 27, 2021 at 6:09 AM Florian Weimer <fweimer@redhat.com> wrote:
> >> >
> >> > * Fangrui Song via Libc-alpha:
> >> >
> >> > > The description needs some adjustment
> >> > > https://www.iso-9899.info/n1570.html#6.6p10
> >> > >
> >> > > 10   An implementation may accept other forms of constant expressions.
> >> >
> >> > Yeah, but the change itself is clearly correct.  Thanks.
> >> >
> >> > Florian
> >> >
> >>
> >> Ugh, you may have missed my point that GCC -O0 and -O2 are not
> >> consistent on whether a `const int` operand can be used in a constant
> >> expression.
> >
> >Yes and that was fixed for GCC 8 by r8-4755.
> >Since you were not specific on which version of GCC, I am assuming it
> >was GCC7.x.
> >
> >Thanks,
> >Andrew Pinski
>
> Sorry for the imprecise description.
> I think the issue is different from your mentioned GCC 8 bugfix.
>
> I commented out these lines in include/libc-symbols.h
>
> -#if !defined __ASSEMBLER__ && !defined __OPTIMIZE__
> -# error "glibc cannot be compiled without optimization"
> -#endif
> +//#if !defined __ASSEMBLER__ && !defined __OPTIMIZE__
> +//# error "glibc cannot be compiled without optimization"
> +//#endif
>
> Next,
>
> a=(../sysdeps/unix/sysv/linux/dl-opendir.c -std=gnu11 -fgnu89-inline -g -Wall -Wwrite-strings -Wundef -fmerge-all-constants -frounding-math -fno-stack-protector -fno-common -Wstrict-prototypes -Wold-style-definition -fmath-errno -fPIC -fno-stack-protector -DSTACK_PROTECTOR_LEVEL=0 -mno-mmx -ftls-model=initial-exec -I../include -I$HOME/Dev/glibc/out/clang/elf -I$HOME/Dev/glibc/out/clang -I../sysdeps/unix/sysv/linux/x86_64/64 -I../sysdeps/unix/sysv/linux/x86_64 -I../sysdeps/unix/sysv/linux/x86/include -I../sysdeps/unix/sysv/linux/x86 -I../sysdeps/x86/nptl -I../sysdeps/unix/sysv/linux/wordsize-64 -I../sysdeps/x86_64/nptl -I../sysdeps/unix/sysv/linux/include -I../sysdeps/unix/sysv/linux -I../sysdeps/nptl -I../sysdeps/pthread -I../sysdeps/gnu -I../sysdeps/unix/inet -I../sysdeps/unix/sysv -I../sysdeps/unix/x86_64 -I../sysdeps/unix -I../sysdeps/posix -I../sysdeps/x86_64/64 -I../sysdeps/x86_64/fpu/multiarch -I../sysdeps/x86_64/fpu -I../sysdeps/x86/fpu -I../sysdeps/x86_64/multiarch -I../sysdeps/x86_64 -I../sysdeps/x86/include -I../sysdeps/x86 -I../sysdeps/ieee754/float128 -I../sysdeps/ieee754/ldbl-96/include -I../sysdeps/ieee754/ldbl-96 -I../sysdeps/ieee754/dbl-64 -I../sysdeps/ieee754/flt-32 -I../sysdeps/wordsize-64 -I../sysdeps/ieee754 -I../sysdeps/generic -I.. -I../libio -I. -D_LIBC_REENTRANT -include $HOME/Dev/glibc/out/clang/libc-modules.h -include ../include/libc-symbols.h -DPIC -DSHARED -DTOP_NAMESPACE=glibc -fsyntax-only)
>
> % gcc-11 $=a -O2  # good
> % gcc-11 $=a -O0  # -O1 is similar
> In file included from ../include/features.h:488,
>                   from ../posix/sys/types.h:25,
>                   from ../include/sys/types.h:1,
>                   from ../sysdeps/unix/sysv/linux/dirstream.h:21,
>                   from ../include/dirent.h:3,
>                   from ../sysdeps/unix/sysv/linux/opendir.c:18,
>                   from ../sysdeps/unix/sysv/linux/dl-opendir.c:1:
> ../sysdeps/unix/sysv/linux/opendir.c: In function ‘__alloc_dir’:
> ../sysdeps/unix/sysv/linux/opendir.c:107:35: error: expression in static assertion is not constant
>    107 |   _Static_assert (allocation_size >= sizeof (struct dirent64),
>        |                   ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../include/sys/cdefs.h:7:59: note: in definition of macro ‘_Static_assert’
>      7 | # define _Static_assert(expr, diagnostic) _Static_assert (expr, diagnostic)
>        |                                                           ^~~~
>
> Then I tested gcc-8, gcc-9, gcc-10 on Debian testing, they have the same behavior as gcc-11.

Please file a bug.

>
> >>
> >> Updated description:
> >>
> >> ---
> >>
> >> linux: Fix a non-constant expression in _Static_assert
> >>
> >> According to C11 6.6p6, `const int` as an operand may not make up a
> >> constant expression. GCC's -O0 and -O2 optimization levels are not
> >> consistent on whether this operand can be used in a constant expression:
> >>
> >> ../sysdeps/unix/sysv/linux/opendir.c:107:19: error: static_assert
> >> expression is not an integral constant expression
> >>   _Static_assert (allocation_size >= sizeof (struct dirent64),
> >>
> >> Use enum which is guaranteed to be a constant expression.
> >> This fixes an error when compiling with GCC -O0 and Clang.
> >>
> >> Fixes: 4b962c9e859de23b461d61f860dbd3f21311e83a ("linux: Simplify
> >> opendir buffer allocation")
Fāng-ruì Sòng Sept. 27, 2021, 6:37 p.m. UTC | #9
On Mon, Sep 27, 2021 at 11:21 AM Andrew Pinski <pinskia@gmail.com> wrote:
>
> On Mon, Sep 27, 2021 at 11:20 AM Fāng-ruì Sòng <maskray@google.com> wrote:
> >
> >
> > On 2021-09-27, Andrew Pinski wrote:
> > >On Mon, Sep 27, 2021 at 10:18 AM Fāng-ruì Sòng via Libc-alpha
> > ><libc-alpha@sourceware.org> wrote:
> > >>
> > >> On Mon, Sep 27, 2021 at 6:09 AM Florian Weimer <fweimer@redhat.com> wrote:
> > >> >
> > >> > * Fangrui Song via Libc-alpha:
> > >> >
> > >> > > The description needs some adjustment
> > >> > > https://www.iso-9899.info/n1570.html#6.6p10
> > >> > >
> > >> > > 10   An implementation may accept other forms of constant expressions.
> > >> >
> > >> > Yeah, but the change itself is clearly correct.  Thanks.
> > >> >
> > >> > Florian
> > >> >
> > >>
> > >> Ugh, you may have missed my point that GCC -O0 and -O2 are not
> > >> consistent on whether a `const int` operand can be used in a constant
> > >> expression.
> > >
> > >Yes and that was fixed for GCC 8 by r8-4755.
> > >Since you were not specific on which version of GCC, I am assuming it
> > >was GCC7.x.
> > >
> > >Thanks,
> > >Andrew Pinski
> >
> > Sorry for the imprecise description.
> > I think the issue is different from your mentioned GCC 8 bugfix.
> >
> > I commented out these lines in include/libc-symbols.h
> >
> > -#if !defined __ASSEMBLER__ && !defined __OPTIMIZE__
> > -# error "glibc cannot be compiled without optimization"
> > -#endif
> > +//#if !defined __ASSEMBLER__ && !defined __OPTIMIZE__
> > +//# error "glibc cannot be compiled without optimization"
> > +//#endif
> >
> > Next,
> >
> > a=(../sysdeps/unix/sysv/linux/dl-opendir.c -std=gnu11 -fgnu89-inline -g -Wall -Wwrite-strings -Wundef -fmerge-all-constants -frounding-math -fno-stack-protector -fno-common -Wstrict-prototypes -Wold-style-definition -fmath-errno -fPIC -fno-stack-protector -DSTACK_PROTECTOR_LEVEL=0 -mno-mmx -ftls-model=initial-exec -I../include -I$HOME/Dev/glibc/out/clang/elf -I$HOME/Dev/glibc/out/clang -I../sysdeps/unix/sysv/linux/x86_64/64 -I../sysdeps/unix/sysv/linux/x86_64 -I../sysdeps/unix/sysv/linux/x86/include -I../sysdeps/unix/sysv/linux/x86 -I../sysdeps/x86/nptl -I../sysdeps/unix/sysv/linux/wordsize-64 -I../sysdeps/x86_64/nptl -I../sysdeps/unix/sysv/linux/include -I../sysdeps/unix/sysv/linux -I../sysdeps/nptl -I../sysdeps/pthread -I../sysdeps/gnu -I../sysdeps/unix/inet -I../sysdeps/unix/sysv -I../sysdeps/unix/x86_64 -I../sysdeps/unix -I../sysdeps/posix -I../sysdeps/x86_64/64 -I../sysdeps/x86_64/fpu/multiarch -I../sysdeps/x86_64/fpu -I../sysdeps/x86/fpu -I../sysdeps/x86_64/multiarch -I../sysdeps/x86_64 -I../sysdeps/x86/include -I../sysdeps/x86 -I../sysdeps/ieee754/float128 -I../sysdeps/ieee754/ldbl-96/include -I../sysdeps/ieee754/ldbl-96 -I../sysdeps/ieee754/dbl-64 -I../sysdeps/ieee754/flt-32 -I../sysdeps/wordsize-64 -I../sysdeps/ieee754 -I../sysdeps/generic -I.. -I../libio -I. -D_LIBC_REENTRANT -include $HOME/Dev/glibc/out/clang/libc-modules.h -include ../include/libc-symbols.h -DPIC -DSHARED -DTOP_NAMESPACE=glibc -fsyntax-only)
> >
> > % gcc-11 $=a -O2  # good
> > % gcc-11 $=a -O0  # -O1 is similar
> > In file included from ../include/features.h:488,
> >                   from ../posix/sys/types.h:25,
> >                   from ../include/sys/types.h:1,
> >                   from ../sysdeps/unix/sysv/linux/dirstream.h:21,
> >                   from ../include/dirent.h:3,
> >                   from ../sysdeps/unix/sysv/linux/opendir.c:18,
> >                   from ../sysdeps/unix/sysv/linux/dl-opendir.c:1:
> > ../sysdeps/unix/sysv/linux/opendir.c: In function ‘__alloc_dir’:
> > ../sysdeps/unix/sysv/linux/opendir.c:107:35: error: expression in static assertion is not constant
> >    107 |   _Static_assert (allocation_size >= sizeof (struct dirent64),
> >        |                   ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
> > ../include/sys/cdefs.h:7:59: note: in definition of macro ‘_Static_assert’
> >      7 | # define _Static_assert(expr, diagnostic) _Static_assert (expr, diagnostic)
> >        |                                                           ^~~~
> >
> > Then I tested gcc-8, gcc-9, gcc-10 on Debian testing, they have the same behavior as gcc-11.
>
> Please file a bug.

Filed https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102502
diff mbox series

Patch

diff --git a/sysdeps/unix/sysv/linux/opendir.c b/sysdeps/unix/sysv/linux/opendir.c
index 48f254d169..88640f44ee 100644
--- a/sysdeps/unix/sysv/linux/opendir.c
+++ b/sysdeps/unix/sysv/linux/opendir.c
@@ -103,7 +103,7 @@  __alloc_dir (int fd, bool close_fd, int flags,
      file system provides a bogus value.  */
   enum { max_buffer_size = 1048576 };
 
-  const size_t allocation_size = 32768;
+  enum { allocation_size = 32768 };
   _Static_assert (allocation_size >= sizeof (struct dirent64),
 		  "allocation_size < sizeof (struct dirent64)");