Re: libbpf build failure on debian:9 with clang

[Andrey Ignatov <rdna@fb.com>]

Arnaldo Carvalho de Melo <acme@kernel.org> [Wed, 2018-10-31 07:12 -0700]:
>   17    40.66 debian:9                      : FAIL gcc (Debian 6.3.0-18+deb9u1) 6.3.0 20170516
> 
> The failure was with clang tho:
> 
> clang version 3.8.1-24 (tags/RELEASE_381/final)
> 
> With:
> 
>   gcc version 6.3.0 20170516 (Debian 6.3.0-18+deb9u1) 
> 
> it built without any warnings/errors.
> 
>   CC       /tmp/build/perf/libbpf.o
> libbpf.c:2201:36: error: comparison of constant -22 with expression of type 'const enum bpf_attach_type' is always false [-Werror,-Wtautological-constant-out-of-range-compare]
>                 if (section_names[i].attach_type == -EINVAL)
>                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^  ~~~~~~~
> 1 error generated.

Hi Arnaldo,

I have a clang version that I can reproduce this error with. Working on
patch.

Thank you for report!


>   CC       /tmp/build/perf/help.o
> mv: cannot stat '/tmp/build/perf/.libbpf.o.tmp': No such file or directory
> /git/linux/tools/build/Makefile.build:96: recipe for target '/tmp/build/perf/libbpf.o' failed
> make[4]: *** [/tmp/build/perf/libbpf.o] Error 1
> 
> This is the cset:
> 
> commit 956b620fcf0b64de403cd26a56bc41e6e4826ea6
> Author: Andrey Ignatov <rdna@fb.com>
> Date:   Wed Sep 26 15:24:53 2018 -0700
> 
>     libbpf: Introduce libbpf_attach_type_by_name
> 
> ------------------------
> 
> Tests are continuing, so far:
> 
>    1    43.53 alpine:3.4                    : Ok   gcc (Alpine 5.3.0) 5.3.0
>    2    58.62 alpine:3.5                    : Ok   gcc (Alpine 6.2.1) 6.2.1 20160822
>    3    51.62 alpine:3.6                    : Ok   gcc (Alpine 6.3.0) 6.3.0
>    4    51.68 alpine:3.7                    : Ok   gcc (Alpine 6.4.0) 6.4.0
>    5    49.38 alpine:3.8                    : Ok   gcc (Alpine 6.4.0) 6.4.0
>    6    79.07 alpine:edge                   : Ok   gcc (Alpine 6.4.0) 6.4.0
>    7    63.35 amazonlinux:1                 : Ok   gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-28)
>    8    59.65 amazonlinux:2                 : Ok   gcc (GCC) 7.3.1 20180303 (Red Hat 7.3.1-5)
>    9    47.39 android-ndk:r12b-arm          : Ok   arm-linux-androideabi-gcc (GCC) 4.9.x 20150123 (prerelease)
>   10    50.64 android-ndk:r15c-arm          : Ok   arm-linux-androideabi-gcc (GCC) 4.9.x 20150123 (prerelease)
>   11    28.75 centos:5                      : Ok   gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-55)
>   12    33.26 centos:6                      : Ok   gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-23)
>   13    43.16 centos:7                      : Ok   gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-28)
>   14    73.61 clearlinux:latest             : FAIL gcc (Clear Linux OS for Intel Architecture) 8.2.1 20180502
>   15    45.56 debian:7                      : Ok   gcc (Debian 4.7.2-5) 4.7.2
>   16    45.53 debian:8                      : Ok   gcc (Debian 4.9.2-10+deb8u1) 4.9.2
>   17    40.66 debian:9                      : FAIL gcc (Debian 6.3.0-18+deb9u1) 6.3.0 20170516
>   18   113.19 debian:experimental           : Ok   gcc (Debian 8.2.0-8) 8.2.0
>   19    41.48 debian:experimental-x-arm64   : Ok   aarch64-linux-gnu-gcc (Debian 8.2.0-7) 8.2.0
>   20    41.51 debian:experimental-x-mips    : Ok   mips-linux-gnu-gcc (Debian 8.2.0-7) 8.2.0
>   21    40.09 debian:experimental-x-mips64  : Ok   mips64-linux-gnuabi64-gcc (Debian 8.1.0-12) 8.1.0
>   22    42.17 debian:experimental-x-mipsel  : Ok   mipsel-linux-gnu-gcc (Debian 8.2.0-7) 8.2.0
>   23    40.02 fedora:20                     : Ok   gcc (GCC) 4.8.3 20140911 (Red Hat 4.8.3-7)
>   24    45.47 fedora:21                     : Ok   gcc (GCC) 4.9.2 20150212 (Red Hat 4.9.2-6)
>   25    41.64 fedora:22                     : Ok   gcc (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6)
>   26    43.60 fedora:23                     : Ok   gcc (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6)
>   27    44.04 fedora:24                     : Ok   gcc (GCC) 6.3.1 20161221 (Red Hat 6.3.1-1)
>   28    37.21 fedora:24-x-ARC-uClibc        : Ok   arc-linux-gcc (ARCompact ISA Linux uClibc toolchain 2017.09-rc2) 7.1.1 20170710
> 
> The problem with clearlinux is unrelated:
> 
> clang-7: error: unknown argument: '-fno-semantic-interposition'
> clang-7: error: unsupported argument '4' to option 'flto='
> clang-7: error: optimization flag '-ffat-lto-objects' is not supported [-Werror,-Wignored-optimization-argument]
> 

-- 
Andrey Ignatov