[Buildroot] [PATCH v4 2/7] package/pkg-meson.mk: add rust cross-compiler support

[Yann E. MORIN]

Antoine, All,

On 2024-02-02 10:36 +0100, Antoine Coutant spake thusly:
> From: Romain Naour <romain.naour at smile.fr>
> 
> This change is needed to be able to build target packages requiring
> rust. If a package has rust in its project or in an add_language()
> call in their meson.build file, meson will try to find a suitable
> compiler for this language[1]. If the language is classified as
> required but not found, it will abort the build.
> 
> It is necessary to specify rust and rust_ld separately in
> support/misc/cross-compilation.conf.in. If you specify it in one line
> just as "rust", it will generate the following warning:
>     WARNING: Please do not put -C linker= in your compiler command,
>     set rust_ld=command in your cross file or use the RUST_LD environment
>     variable, otherwise meson will override your selection.
> 
> [1] https://mesonbuild.com/Reference-manual_functions.html#add_languages
> 
> Signed-off-by: Romain Naour <romain.naour at smile.fr>
> Signed-off-by: Sebastian Weyer <sebastian.weyer at smile.fr>
> Signed-off-by: Antoine Coutant <antoine.coutant at smile.fr>
> ---
>  package/pkg-meson.mk                   | 13 +++++++++++++
>  support/misc/cross-compilation.conf.in |  2 ++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/package/pkg-meson.mk b/package/pkg-meson.mk
> index 65cabf23ba..25dd4f0d7f 100644
> --- a/package/pkg-meson.mk
> +++ b/package/pkg-meson.mk
> @@ -82,6 +82,16 @@ else
>  PKG_MESON_TARGET_FC = /bin/false
>  endif
>  
> +ifeq ($(BR2_PACKAGE_HOST_RUSTC),y)
> +PKG_MESON_TARGET_RUSTC = $(HOST_DIR)/bin/rustc
> +PKG_MESON_TARGET_RUSTC_LINKER = $(notdir $(TARGET_CROSS))gcc

Why can't PKG_MESON_TARGET_RUSTC_LINKER be an absolute path, when
PKG_MESON_TARGET_RUSTC is one, and [...]

> +PKG_MESON_TARGET_RUSTC_TARGET_NAME = $(RUSTC_TARGET_NAME)
> +else
> +PKG_MESON_TARGET_RUSTC = /bin/false
> +PKG_MESON_TARGET_RUSTC_LINKER = /bin/false

[...] especially since here PKG_MESON_TARGET_RUSTC_LINKER is an absolute
path?

Regards,
Yann E. MORIN.

> +PKG_MESON_TARGET_RUSTC_TARGET_NAME =
> +endif
> +
>  # Generates sed patterns for patching the cross-compilation.conf template,
>  # since Flags might contain commas the arguments are passed indirectly by
>  # variable name (stripped to deal with whitespaces).
> @@ -91,6 +101,7 @@ define PKG_MESON_CROSSCONFIG_SED
>          -e "s%@TARGET_CXX@%$(PKG_MESON_TARGET_CXX)%g" \
>          -e "s%@TARGET_AR@%$(TARGET_AR)%g" \
>          -e "s%@TARGET_FC@%$(PKG_MESON_TARGET_FC)%g" \
> +        -e "s%@TARGET_RUSTC@%$(PKG_MESON_TARGET_RUSTC)%g" \
>          -e "s%@TARGET_STRIP@%$(TARGET_STRIP)%g" \
>          -e "s%@TARGET_ARCH@%$(PKG_MESON_TARGET_CPU_FAMILY)%g" \
>          -e "s%@TARGET_CPU@%$(GCC_TARGET_CPU)%g" \
> @@ -99,6 +110,8 @@ define PKG_MESON_CROSSCONFIG_SED
>          -e "s%@TARGET_CFLAGS@%$(call make-sq-comma-list,$($(strip $(1))))%g" \
>          -e "s%@TARGET_LDFLAGS@%$(call make-sq-comma-list,$($(strip $(3))))%g" \
>          -e "s%@TARGET_CXXFLAGS@%$(call make-sq-comma-list,$($(strip $(2))))%g" \
> +        -e "s%@TARGET_RUSTC_LINKER@%$(PKG_MESON_TARGET_RUSTC_LINKER)%g" \
> +        -e "s%@RUSTC_TARGET_NAME@%$(PKG_MESON_TARGET_RUSTC_TARGET_NAME)%g" \
>          -e "s%@BR2_CMAKE@%$(BR2_CMAKE)%g" \
>          -e "s%@PKGCONF_HOST_BINARY@%$(HOST_DIR)/bin/pkgconf%g" \
>          -e "s%@HOST_DIR@%$(HOST_DIR)%g" \
> diff --git a/support/misc/cross-compilation.conf.in b/support/misc/cross-compilation.conf.in
> index a58ab553d0..21cec10b82 100644
> --- a/support/misc/cross-compilation.conf.in
> +++ b/support/misc/cross-compilation.conf.in
> @@ -13,6 +13,8 @@ fortran = '@TARGET_FC@'
>  pkg-config = '@PKGCONF_HOST_BINARY@'
>  g-ir-compiler = '@STAGING_DIR@/usr/bin/g-ir-compiler'
>  g-ir-scanner = '@STAGING_DIR@/usr/bin/g-ir-scanner'
> +rust = ['@TARGET_RUSTC@', '--target', '@RUSTC_TARGET_NAME@' ]
> +rust_ld = '@TARGET_RUSTC_LINKER@'
>  
>  [built-in options]
>  c_args = [@TARGET_CFLAGS@]
> -- 
> 2.25.1
> 
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