Re: [PATCH] xfsprogs: fix warnings/errors due to missing include

["Holger Hoffstätte" <holger@applied-asynchrony.com>]

On 2022-10-04 20:40, Darrick J. Wong wrote:
> On Tue, Oct 04, 2022 at 08:34:23PM +0200, Holger Hoffstätte wrote:
>> On 2022-10-04 20:28, Darrick J. Wong wrote:
>>> On Tue, Oct 04, 2022 at 08:11:05PM +0200, Holger Hoffstätte wrote:
>>>>
>>>> Gentoo is currently trying to rebuild the world with clang-16, uncovering exciting
>>>> new errors in many packages since several warnings have been turned into errors,
>>>> among them missing prototypes, as documented at:
>>>> https://discourse.llvm.org/t/clang-16-notice-of-potentially-breaking-changes/65562
>>>>
>>>> xfsprogs came up, with details at https://bugs.gentoo.org/875050.
>>>>
>>>> The problem was easy to find: a missing include for the u_init/u_cleanup
>>>> prototypes. The error:
>>>>
>>>> Building scrub
>>>>       [CC]     unicrash.o
>>>> unicrash.c:746:2: error: call to undeclared function 'u_init'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
>>>>           u_init(&uerr);
>>>>           ^
>>>> unicrash.c:746:2: note: did you mean 'u_digit'?
>>>> /usr/include/unicode/uchar.h:4073:1: note: 'u_digit' declared here
>>>> u_digit(UChar32 ch, int8_t radix);
>>>> ^
>>>> unicrash.c:754:2: error: call to undeclared function 'u_cleanup'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
>>>>           u_cleanup();
>>>>           ^
>>>> 2 errors generated.
>>>>
>>>> The complaint is valid and the fix is easy enough: just add the missing include.
>>>>
>>>> Signed-off-by: Holger Hoffstätte <holger@applied-asynchrony.com>
>>>
>>> Aha, that explains why I kept hearing reports about this but could never
>>> get gcc to spit out this error.  Thanks for fixing this.
>>
>> You're welcome. This reproduces with gcc when explicitly enabled:
>>
>> $CFLAGS="-Werror=implicit-function-declaration -Werror=implicit-int" ./configure
> 
> Huh.  I don't know why my system won't complain.
> 
> $ gcc --version
> gcc (Ubuntu 11.2.0-19ubuntu1) 11.2.0
> Copyright (C) 2021 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions.  There is
> NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
> PURPOSE.
> 
> $ gcc -Wall -g -O3 -fstack-protector --param=ssp-buffer-size=4
> -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3 -D_FILE_OFFSET_BITS=64
> -Wno-address-of-packed-member -femit-struct-debug-detailed=any
> -Wno-error=unused-but-set-variable -Wuninitialized -Wno-pointer-sign
> -Wall -Wextra -Wno-unused-parameter -fstack-usage -Werror
> -Wno-sign-compare -Wno-missing-field-initializers -Wmaybe-uninitialized
> -Wno-error=unused-function -Wno-error=unused-variable
> -Wno-error=maybe-uninitialized -Werror=implicit-function-declaration
> -Werror=implicit-int   -g -O2 -DDEBUG
> -DVERSION=\"6.1.0-rc0~WIP-2022-10-03\" -DLOCALEDIR=\"/usr/share/locale\"
> -DPACKAGE=\"xfsprogs\" -I../include -I../libxfs -I.. -D_LGPL_SOURCE
> -D_GNU_SOURCE -funsigned-char -fno-strict-aliasing -Wall -Werror -Wextra
> -Wno-unused-parameter -DHAVE_MNTENT -DHAVE_FSETXATTR -DENABLE_BLKID
> -DHAVE_GETFSMAP -DHAVE_GETFSREFCOUNTS -DHAVE_FALLOCATE
> -DHAVE_LIBURCU_ATOMIC64 -DHAVE_MALLINFO -DHAVE_MALLINFO2 -DHAVE_SYNCFS
> -DHAVE_LIBATTR -DHAVE_LIBICU  -DHAVE_SG_IO -DHAVE_HDIO_GETGEO -c
> unicrash.c
> $

holger>gcc --version
gcc (Gentoo 12.2.0 p1) 12.2.0
..
holger>cd /tmp
holger>tar xf /var/cache/distfiles/xfsprogs-5.18.0.tar.xz
holger>cd xfsprogs-5.18.0
holger>CFLAGS="-pipe -O2 -Werror=implicit-function-declaration -Werror=implicit-int" ./configure && make -j8
...
     [CC]     unicrash.o
unicrash.c: In function 'unicrash_load':
unicrash.c:746:9: error: implicit declaration of function 'u_init'; did you mean 'u_digit'? [-Werror=implicit-function-declaration]
   746 |         u_init(&uerr);
       |         ^~~~~~
       |         u_digit
unicrash.c: In function 'unicrash_unload':
unicrash.c:754:9: error: implicit declaration of function 'u_cleanup'; did you mean 'scrub_cleanup'? [-Werror=implicit-function-declaration]
   754 |         u_cleanup();
       |         ^~~~~~~~~
       |         scrub_cleanup
     [CC]     link.o
     [CC]     mmap.o
     [SED]    xfs_scrub_all
     [CC]     open.o
     [SED]    xfs_scrub_all.cron
     [CC]     parent.o
cc1: some warnings being treated as errors

Alternatively add CC=clang to the configure line and check out the other
nice warnings as well. :)

cheers
Holger