Re: "krb" fails to build, suspect GCC bug

[Martin Jansa <martin.jansa@gmail.com>]

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On Tue, Oct 27, 2015 at 08:57:42PM +0100, Martin Jansa wrote:
> On Tue, Oct 27, 2015 at 11:26:32AM -0700, Khem Raj wrote:
> > On Tue, Oct 27, 2015 at 11:21 AM, Martin Jansa <martin.jansa@gmail.com> wrote:
> > > On Sat, Sep 05, 2015 at 02:39:14PM +0200, Mike Looijmans wrote:
> > >> I got this weird build failure from the "krb" package:
> > >>
> > >> | make[3]: Entering directory
> > >> '/TOPDIR/build/tmp/work/mips32el-oe-linux/krb5/1.13.2-r0/krb5-1.13.2/src/lib/krb5/ccache'
> > >> | mipsel-oe-linux-gcc  -mel -mabi=32 -mhard-float -march=mips32
> > >> --sysroot=/TOPDIR/build/tmp/sysroots/formuler1 -fPIC -DSHARED
> > >> -DHAVE_CONFIG_H  -I../../../include -I../../../include -I./ccapi -I. -I.
> > >>   -DKRB5_DEPRECATED=1 -DKRB5_PRIVATE  -Os -pipe -g
> > >> -feliminate-unused-debug-types -DDESTRUCTOR_ATTR_WORKS=1
> > >> -I/TOPDIR/build/tmp/sysroots/formuler1/usr/include/et -Wall -Wcast-align
> > >> -Wshadow -Wmissing-prototypes -Wno-format-zero-length -Woverflow
> > >> -Wstrict-overflow -Wmissing-format-attribute -Wmissing-prototypes
> > >> -Wreturn-type -Wmissing-braces -Wparentheses -Wswitch -Wunused-function
> > >> -Wunused-label -Wunused-variable -Wunused-value -Wunknown-pragmas
> > >> -Wsign-compare -Werror=uninitialized -Werror=pointer-arith
> > >> -Werror=declaration-after-statement
> > >> -Werror-implicit-function-declaration -pthread -c cc_file.c -o
> > >> cc_file.so.o && mv -f cc_file.so.o cc_file.so
> > >> | cc_file.c: In function 'fcc_next_cred':
> > >> | cc_file.c:368:9: error: 'maxsize' may be used uninitialized in this
> > >> function [-Werror=maybe-uninitialized]
> > >> |      ret = load_data(context, id, maxsize, buf);
> > >> |          ^
> > >> | cc_file.c:1091:12: note: 'maxsize' was declared here
> > >> |      size_t maxsize;
> > >> |             ^
> > >> | cc1: some warnings being treated as errors
> > >>
> > >> Looking at the source, this doesn't make any sense at all. The
> > >> declaration of the variable isn't even in the same method body. And the
> > >> line it complains about is about the fifth time it passes that variable
> > >> to another method.
> > >>
> > >> And working around it by initializing maxsize=0 just makes the compiler
> > >> choke on a similar situation elsewhere:
> > >> | packet.c:50:67: error: 'id' may be used uninitialized in this function
> > >>
> > >>
> > >> I suspect the problem here is GCC and not the krb code. Anyone seen this?
> > >
> > > I've seen it today in my world builds, It seems to fail only when building with -Os.
> > >
> > > I've seen similar issue in mdadm, also only with -Os.
> > >
> > 
> > is this regression ? or seen for first time?
> 
> krb5 fails to build like this with -Os at least since dizzy
> 
> mdadm failure:
> | raid6check.c: In function 'check_stripes':
> | raid6check.c:315:8: error: 'stripe_buf' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> |   char *stripe_buf;
> |         ^
> | cc1: all warnings being treated as errors
> | make: *** [raid6check.o] Error 1
> | ERROR: oe_runmake failed
> 
> is newer (seen only in Jethro builds).
> 
> But maybe only because this is built in do_compile_ptest_base and ptest
> support was added in oe-core/jethro, it fails the same with gcc-5.2 and gcc-4.9.

Quick grep in my last -Os world build shows 2 more recipes with
similar issue (smbnetfs is failing in krb5 dependency already):

physfs:
| physfs/2.0.3-r0/physfs-2.0.3/archivers/zip.c: In function 'ZIP_openArchive':
| physfs/2.0.3-r0/physfs-2.0.3/archivers/zip.c:944:19: error: 'data_start' may be used uninitialized in this function [-Werror=maybe-uninitialized]
|      entry->offset += ofs_fixup;
|                    ^
| physfs/2.0.3-r0/physfs-2.0.3/archivers/zip.c:1116:19: note: 'data_start' was declared here
|      PHYSFS_uint32 data_start;
|                    ^
| physfs/2.0.3-r0/physfs-2.0.3/archivers/zip.c: In function 'ZIP_openArchive':
| physfs/2.0.3-r0/physfs-2.0.3/archivers/zip.c:944:19: error: 'data_start' may be used uninitialized in this function [-Werror=maybe-uninitialized]
|      entry->offset += ofs_fixup;
|                    ^
| physfs/2.0.3-r0/physfs-2.0.3/archivers/zip.c:1116:19: note: 'data_start' was declared here
|      PHYSFS_uint32 data_start;
|                    ^
| cc1: all warnings being treated as errors

tvheadend:
| tvheadend/3.3-r0/git/src/serviceprobe.c: In function 'serviceprobe_thread':
| tvheadend/3.3-r0/git/src/serviceprobe.c:168:7: error: 's' may be used uninitialized in this function [-Werror=maybe-uninitialized]
|        subscription_unsubscribe(s);
|        ^

-- 
Martin 'JaMa' Jansa     jabber: Martin.Jansa@gmail.com

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