[committed] libstdc++: Decouple HAVE_FCNTL_H from HAVE_DIRENT_H check

[Jonathan Wakely <jwakely.gcc@gmail.com>]

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On Tue, 8 Feb 2022 at 21:18, Jonathan Wakely wrote:

>
>
> On Tue, 8 Feb 2022 at 21:02, Dimitar Dimitrov <dimitar@dinux.eu> wrote:
>
>> On Mon, Feb 07, 2022 at 09:05:45PM +0000, Jonathan Wakely wrote:
>> > On Mon, 7 Feb 2022 at 21:01, Jonathan Wakely <jwakely.gcc@gmail.com>
>> wrote:
>> >
>> > >
>> > >
>> > > On Mon, 7 Feb 2022 at 20:12, Dimitar Dimitrov <dimitar@dinux.eu>
>> wrote:
>> > >
>> > >> On PRU target with newlib, we have the following combination in
>> config.h:
>> > >>   /* #undef HAVE_DIRENT_H */
>> > >>   #define HAVE_FCNTL_H 1
>> > >>   #define HAVE_UNLINKAT 1
>> > >>
>> > >> In newlib, targets which do not define dirent.h, get a build error
>> when
>> > >> including <dirent.h>:
>> > >>
>> > >>
>> https://sourceware.org/git/?p=newlib-cygwin.git;a=blob;f=newlib/libc/include/sys/dirent.h;hb=HEAD
>> > >>
>> > >> While fs_dir.cc correctly checks for HAVE_FCNTL_H, dir-common.h
>> doesn't,
>> > >> and instead uses HAVE_DIRENT_H. This results in unlinkat() function
>> call
>> > >> in fs_dir.cc without the needed <fcntl.h> include in dir-common.h.
>> Thus
>> > >> a build failure:
>> > >>   .../gcc/libstdc++-v3/src/c++17/fs_dir.cc:151:11: error:
>> ‘::unlinkat’
>> > >> has not been declared; did you mean ‘unlink’?
>> > >>
>> > >> Fix by encapsulating <fcntl.h> include with the correct check.
>> > >>
>> > >
>> > > But there's no point doing anything in that file if we don't have
>> > > <dirent.h>, the whole thing is unusable. There's no point making the
>> > > members using unlinkat compile if you can't ever construct the type.
>> > >
>> > > So I think we want a different fix.
>> > >
>> >
>> >
>> > Maybe something like:
>> >
>> > --- a/libstdc++-v3/src/filesystem/dir-common.h
>> > +++ b/libstdc++-v3/src/filesystem/dir-common.h
>> > @@ -70,6 +70,8 @@ struct DIR { };
>> > inline DIR* opendir(const char*) { return nullptr; }
>> > inline dirent* readdir(DIR*) { return nullptr; }
>> > inline int closedir(DIR*) { return -1; }
>> > +#undef _GLIBCXX_HAVE_DIRFD
>> > +#undef _GLIBCXX_HAVE_UNLINKAT
>> > #endif
>> > } // namespace __gnu_posix
>> Yes, this fixes the PRU target, and does not regress
>> x86_64-pc-linux-gnu.
>>
>
> Thanks for checking it. I'm just testing it myself on
> powerpc64le-linux-gnu and will push when it finishes.
>
>
Sorry for the delay, that's pushed to trunk now.

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commit 3d5f4f76e6db0895181ebca538748379bfe6058f
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Tue Feb 8 21:05:30 2022

    libstdc++: Fix directory iterator build for newlib
    
    When building for newlib HAVE_OPENAT and HAVE_UNLINKAT are (sometimes?)
    defined, but <fcntl.h> is only included when HAVE_DIRENT_H is defined.
    Since directory iterators are completely useless without <dirent.h>,
    just override the HAVE_OPENAT and HAVE_UNLINKAT detection when we don't
    have <dirent.h>.
    
    libstdc++-v3/ChangeLog:
    
            * src/filesystem/dir-common.h (_GLIBCXX_HAVE_DIRFD): Undefine
            when <dirent.h> is not available.
            (_GLIBCXX_HAVE_UNLINKAT):  Likewise.

diff --git a/libstdc++-v3/src/filesystem/dir-common.h b/libstdc++-v3/src/filesystem/dir-common.h
index 511b988f1c7..365fd527f4d 100644
--- a/libstdc++-v3/src/filesystem/dir-common.h
+++ b/libstdc++-v3/src/filesystem/dir-common.h
@@ -70,6 +70,8 @@ struct DIR { };
 inline DIR* opendir(const char*) { return nullptr; }
 inline dirent* readdir(DIR*) { return nullptr; }
 inline int closedir(DIR*) { return -1; }
+#undef _GLIBCXX_HAVE_DIRFD
+#undef _GLIBCXX_HAVE_UNLINKAT
 #endif
 } // namespace __gnu_posix