Re: [PATCH] config.guess: combine two heuristics to detect musl libc

[Dmitry V. Levin]

On Sat, Nov 07, 2020 at 02:30:32PM -0800, Cheng XU wrote:
> Sorry for the late response. The patch looks good to me. Hope it can be 
> accepted soon to fix the problem in downstream projects.
> 
> Best Regards,
> 
> Cheng

The patch has been applied, thanks.

> On Nov 5, 2020, 5:41 PM -0800, Dmitry V. Levin <ldv@altlinux.org>, wrote:
> > Apparently, this is needed to correctly detect musl libc in different
> > versions of Alpine Linux.
> >
> > According to
> > https://lists.gnu.org/archive/html/config-patches/2020-09/msg00002.html,
> > the ldd based check does not work for some old versions of the Alpine Linux,
> > and, according to
> > https://lists.gnu.org/archive/html/config-patches/2020-11/msg00002.html,
> > the compiler may not be available in a fresh Alpine container.
> >
> > The ldd based check is essentially the same as the check that was
> > introduced by commit 3d00f60242f1726fc6eaa38e09435a969ee7ebe5, it is
> > performed iff the compiler based check could not give a definitive
> > answer.
> >
> > Reported-by: Cheng XU <xucheng@me.com>
> > Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
> > ---
> > ChangeLog | 4 ++++
> > config.guess | 22 +++++++++++++++++-----
> > 2 files changed, 21 insertions(+), 5 deletions(-)
> >
> > diff --git a/ChangeLog b/ChangeLog
> > index 06a7553..8e97a97 100644
> > --- a/ChangeLog
> > +++ b/ChangeLog
> > @@ -1,3 +1,7 @@
> > +2020-11-05 Dmitry V. Levin <ldv@altlinux.org>
> > +
> > + * config.guess: Combine two heuristics to detect musl libc.
> > +
> > 2020-10-22 Rin Okuyama <rin@netbsd.org>
> >
> > * config.guess (*:NetBSD:*:*): Handle aarch64eb.
> > diff --git a/config.guess b/config.guess
> > index 12dd5b4..b5456f8 100755
> > --- a/config.guess
> > +++ b/config.guess
> > @@ -138,9 +138,7 @@ UNAME_VERSION=`(uname -v) 2>/dev/null` || 
> > UNAME_VERSION=unknown
> >
> > case "$UNAME_SYSTEM" in
> > Linux|GNU|GNU/*)
> > - # If the system lacks a compiler, then just pick glibc.
> > - # We could probably try harder.
> > - LIBC=gnu
> > + LIBC=unknown
> >
> > set_cc_for_build
> > cat <<-EOF > "$dummy.c"
> > @@ -149,16 +147,30 @@ Linux|GNU|GNU/*)
> > LIBC=uclibc
> > #elif defined(__dietlibc__)
> > LIBC=dietlibc
> > + #elif defined(__GLIBC__)
> > + LIBC=gnu
> > #else
> > #include <stdarg.h>
> > + /* First heuristic to detect musl libc. */
> > #ifdef __DEFINED_va_list
> > LIBC=musl
> > - #else
> > - LIBC=gnu
> > #endif
> > #endif
> > EOF
> > eval "`$CC_FOR_BUILD -E "$dummy.c" 2>/dev/null | grep '^LIBC' | sed 's, 
> > ,,g'`"
> > +
> > + # Second heuristic to detect musl libc.
> > + if [ "$LIBC" = unknown ] &&
> > + command -v ldd >/dev/null &&
> > + ldd --version 2>&1 | grep -q ^musl; then
> > + LIBC=musl
> > + fi
> > +
> > + # If the system lacks a compiler, then just pick glibc.
> > + # We could probably try harder.
> > + if [ "$LIBC" = unknown ]; then
> > + LIBC=gnu
> > + fi
> > ;;
> > esac
> >
> > --
> > ldv

-- 
ldv