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

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

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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.

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

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