Re: [gentoo-dev] [PATCH 4/5] cargo.eclass: Enable dynamic linking by default

[James Le Cuirot <chewi@gentoo.org>]

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On Sat, 2025-03-08 at 15:59 +0200, Arthur Zamarin wrote:
> From: Michal Rostecki <vadorovsky@protonmail.com>
> 
> Rust defaults to static linking (`-C target-feature=+crt-static`) on
> musl targets. We already patch dev-lang/rust to always prefer dynamic
> linking, but to ensure that behavior with dev-lang/rust-bin, set the
> opposite option (`-C target-feature=-crt-static`) in RUSTFLAGS.
> 
> Bug: https://bugs.gentoo.org/940722
> Signed-off-by: Michal Rostecki <vadorovsky@protonmail.com>
> Closes: https://github.com/gentoo/gentoo/pull/40797
> Signed-off-by: Arthur Zamarin <arthurzam@gentoo.org>
> ---
>  eclass/cargo.eclass | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/eclass/cargo.eclass b/eclass/cargo.eclass
> index 909321c355b..dae2b93f24f 100644
> --- a/eclass/cargo.eclass
> +++ b/eclass/cargo.eclass
> @@ -745,10 +745,15 @@ cargo_env() {
>  	# The default linker is "cc" so override by setting linker to CC in the
>  	# RUSTFLAGS. The given linker cannot include any arguments, so split these
>  	# into link-args along with LDFLAGS.
> +	#
> +	# Rust defaults to static linking (-C target-feature=+crt-static) on musl
> +	# targets. We already patch dev-lang/rust to always prefer dynamic linking,
> +	# but to ensure that behavior with dev-lang/rust-bin, set the opposite option
> +	# (-C target-feature=-crt-static) in RUSTFLAGS.
>  	local -x CARGO_BUILD_TARGET=$(rust_abi)
>  	local TRIPLE=${CARGO_BUILD_TARGET//-/_}
>  	local TRIPLE=${TRIPLE^^} LD_A=( $(tc-getCC) ${LDFLAGS} )
> -	local -Ix CARGO_TARGET_"${TRIPLE}"_RUSTFLAGS+=" -C strip=none -C linker=${LD_A[0]}"
> +	local -Ix CARGO_TARGET_"${TRIPLE}"_RUSTFLAGS+=" -C strip=none -C linker=${LD_A[0]} -C target-feature=-crt-static"
>  	[[ ${#LD_A[@]} -gt 1 ]] && local CARGO_TARGET_"${TRIPLE}"_RUSTFLAGS+="$(printf -- ' -C link-arg=%s' "${LD_A[@]:1}")"
>  	local CARGO_TARGET_"${TRIPLE}"_RUSTFLAGS+=" ${RUSTFLAGS}"

I considered this when writing the above lines, but I wasn't sure if it was a
good idea. If the testing has been done, then I'm glad to see it.


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