Re: [PATCH 2/2] glibc: Disable Werror when building with debug options

From: Martin Jansa <martin.jansa@gmail.com>
To: Andre McCurdy <armccurdy@gmail.com>
Cc: OE Core mailing list <openembedded-core@lists.openembedded.org>
Subject: Re: [PATCH 2/2] glibc: Disable Werror when building with debug options
Date: Wed, 27 Feb 2019 23:32:29 +0100	[thread overview]
Message-ID: <20190227223229.GA1503@jama> (raw)
In-Reply-To: <CAJ86T=WH03EBVFh-OU=pKDcsKL-YK3efEzHXDmwouGjvp7z9GQ@mail.gmail.com>

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On Wed, Feb 27, 2019 at 02:01:06PM -0800, Andre McCurdy wrote:
> On Wed, Feb 27, 2019 at 12:51 PM Khem Raj <raj.khem@gmail.com> wrote:
> >
> > Since compiler does not optimize away a lot of stuff we end up with
> > Werrors e.g.
> >
> > ./sysdeps/ieee754/flt-32/s_log1pf.c: In function '__log1pf':
> > ../sysdeps/ieee754/flt-32/s_log1pf.c:114:22: error: 'c' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> >   114 |        + (k * ln2_lo + c))) - f);
> >       |          ~~~~~~~~~~~~^~~~
> >
> > which otherwise wont happen, so lets build with warnings-as-errors
> > disabled in debug mode
> >
> > given we disable werror, now we don't have to restrict user to compile
> > without -O0
> 
> Did you actually test with -O0? Even if it builds, there may be issues
> at runtime:
> 
>   https://sourceware.org/glibc/wiki/FAQ#Why_do_I_get:.60.23error_.22glibc_cannot_be_compiled_without_optimization.22.27.2C_when_trying_to_compile_GNU_libc_with_GNU_CC.3F

Agreed, last time I've tried it still didn't work in runtime with -O0.

If this is the only place where it now fails, can we please work around
it like in:
https://sourceware.org/git/?p=glibc.git;a=commit;h=27c5e756a2a8495d77480a103081a86c1ca9a1e8
https://sourceware.org/git/?p=glibc.git;a=commit;h=4a06ceea33ecc220bbfe264d8f1e74de2f04e90d
and pending:
https://patches-gcc.linaro.org/patch/13529/

> >  meta/recipes-core/glibc/glibc.inc     | 9 ---------
> >  meta/recipes-core/glibc/glibc_2.29.bb | 1 +
> >  2 files changed, 1 insertion(+), 9 deletions(-)
> >
> > diff --git a/meta/recipes-core/glibc/glibc.inc b/meta/recipes-core/glibc/glibc.inc
> > index 67af396133..a382a22b73 100644
> > --- a/meta/recipes-core/glibc/glibc.inc
> > +++ b/meta/recipes-core/glibc/glibc.inc
> > @@ -2,15 +2,6 @@ require glibc-common.inc
> >  require glibc-ld.inc
> >  require glibc-testing.inc
> >
> > -python () {
> > -    opt_effective = "-O"
> > -    for opt in d.getVar('SELECTED_OPTIMIZATION').split():
> > -        if opt in ("-O0", "-O", "-O1", "-O2", "-O3", "-Os"):
> > -            opt_effective = opt
> > -    if opt_effective == "-O0":
> > -        bb.fatal("%s can't be built with %s, try -O1 instead" % (d.getVar('PN'), opt_effective))
> > -}
> > -
> >  DEPENDS = "virtual/${TARGET_PREFIX}gcc libgcc-initial linux-libc-headers"
> >
> >  PROVIDES = "virtual/libc"
> > diff --git a/meta/recipes-core/glibc/glibc_2.29.bb b/meta/recipes-core/glibc/glibc_2.29.bb
> > index bd8aa6d503..9b6fab066b 100644
> > --- a/meta/recipes-core/glibc/glibc_2.29.bb
> > +++ b/meta/recipes-core/glibc/glibc_2.29.bb
> > @@ -90,6 +90,7 @@ EXTRA_OECONF = "--enable-kernel=${OLDEST_KERNEL} \
> >                  --disable-crypt \
> >                  --with-default-link \
> >                  --enable-nscd \
> > +                ${@bb.utils.contains_any('SELECTED_OPTIMIZATION', '-O0 -Og', '--disable-werror', '', d)} \
> >                  ${GLIBCPIE} \
> >                  ${GLIBC_EXTRA_OECONF}"
> >
> > --
> > 2.21.0
> >
> > --
> > _______________________________________________
> > Openembedded-core mailing list
> > Openembedded-core@lists.openembedded.org
> > http://lists.openembedded.org/mailman/listinfo/openembedded-core
> -- 
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-- 
Martin 'JaMa' Jansa     jabber: Martin.Jansa@gmail.com

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