Re: [PATCH v2] kbuild: Make ld-version.sh more robust against version string changes

[Nicolas Schier <nicolas@fjasle.eu>]

On Sun, Jul 07, 2024 at 10:06:47PM -0700 Nathan Chancellor wrote:
> After [1] in upstream LLVM, ld.lld's version output became slightly
> different when the cmake configuration option LLVM_APPEND_VC_REV is
> disabled.
> 
> Before:
> 
>   Debian LLD 19.0.0 (compatible with GNU linkers)
> 
> After:
> 
>   Debian LLD 19.0.0, compatible with GNU linkers
> 
> This results in ld-version.sh failing with
> 
>   scripts/ld-version.sh: 18: arithmetic expression: expecting EOF: "10000 * 19 + 100 * 0 + 0,"
> 
> because the trailing comma is included in the patch level part of the
> expression. While [1] has been partially reverted in [2] to avoid this
> breakage (as it impacts the configuration stage and it is present in all
> LTS branches), it would be good to make ld-version.sh more robust
> against such miniscule changes like this one.
> 
> Use POSIX shell parameter expansion [3] to remove the largest suffix
> after just numbers and periods, replacing of the current removal of
> everything after a hyphen. ld-version.sh continues to work for a number
> of distributions (Arch Linux, Debian, and Fedora) and the kernel.org
> toolchains and no longer errors on a version of ld.lld with [1].
> 
> Fixes: 02aff8592204 ("kbuild: check the minimum linker version in Kconfig")
> Link: https://github.com/llvm/llvm-project/commit/0f9fbbb63cfcd2069441aa2ebef622c9716f8dbb [1]
> Link: https://github.com/llvm/llvm-project/commit/649cdfc4b6781a350dfc87d9b2a4b5a4c3395909 [2]
> Link: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html [3]
> Suggested-by: Fangrui Song <maskray@google.com>
> Reviewed-by: Fangrui Song <maskray@google.com>
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
> Changes in v2:
> - Move to a pattern matching notation with remove largest suffix to
>   remove everything after just numbers and periods.
> - The LLVM change that prompted this has been partially reverted to
>   avoid this problem, so reword commit message to reflect this is being
>   done defensively. As such, remove 'Cc: stable@vger.kernel.org'. If it
>   is needed there at some point, it can just be manually backported (or
>   it will just get AUTOSEL'd).
> - Add tags for Fangrui's suggestion and review on v1.
> - Link to v1: https://lore.kernel.org/r/20240704-update-ld-version-for-new-lld-ver-str-v1-1-91bccc020a93@kernel.org
> ---
>  scripts/ld-version.sh | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/scripts/ld-version.sh b/scripts/ld-version.sh
> index a78b804b680c..b9513d224476 100755
> --- a/scripts/ld-version.sh
> +++ b/scripts/ld-version.sh
> @@ -57,9 +57,11 @@ else
>  	fi
>  fi
>  
> -# Some distributions append a package release number, as in 2.34-4.fc32
> -# Trim the hyphen and any characters that follow.
> -version=${version%-*}
> +# There may be something after the version, such as a distribution's package
> +# release number (like Fedora's "2.34-4.fc32") or punctuation (like LLD briefly
> +# added before the "compatible with GNU linkers" string), so remove everything
> +# after just numbers and periods.
> +version=${version%%[!0-9.]*}
>  
>  cversion=$(get_canonical_version $version)
>  min_cversion=$(get_canonical_version $min_version)
> 
> ---

thanks!

Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>