[Buildroot] [PATCH v3 1/1] package/pkg-meson: use meson to build/install packages

[Yann E. MORIN]

James, All,

On 2022-07-22 00:09 -0600, James Hilliard spake thusly:
> As of version 0.54.0 meson has had the ability to build and install
> packages rather than having to run ninja directly as before.
> 
> This will allow us to use features such as meson install tags in
> the future which require meson to be used for the installation.
> 
> It appears we need to ensure the cmake prefix path is set for the
> meson generated relocatable pkg-config format to work properly.
> 
> Signed-off-by: James Hilliard <james.hilliard1 at gmail.com>
> ---
[--SNIP--]
> diff --git a/docs/manual/adding-packages-meson.txt b/docs/manual/adding-packages-meson.txt
> index 029c8c2488..c8aed65c2f 100644
> --- a/docs/manual/adding-packages-meson.txt
> +++ b/docs/manual/adding-packages-meson.txt
> @@ -125,8 +125,8 @@ will therefore only use a few of them.
>    +c_link_args+, +cpp_args+, +cpp_link_args+, +sys_root+, and
>    +pkg_config_libdir+.
>  
> -* +FOO_NINJA_ENV+, to specify additional environment variables to pass to
> -  +ninja+, meson companion tool in charge of the build operations. By default,
> +* +FOO_MESON_ENV+, to specify additional environment variables to pass to
> +  +meson+, meson tool in charge of the build/install operations. By default,
>    empty.

IIRC, the topic of what to do about external packages that set their
FOO_NINJA_ENV, was raised in a previous iteration.

I understand that the conclusion was basically "the probability is low,
we don't handle it". This should have been noted in the commit log.

>  * +FOO_NINJA_OPTS+, to specify a space-separated list of targets to build. By

Now that we use meson to build and instal, does it still make sense to
have FOO_NINJA_OPTS to be the list of targets to install?

I mean, isn't there a way to tell meson what to install, instead?

[--SNIP--]
> diff --git a/package/pkg-cmake.mk b/package/pkg-cmake.mk
> index 3b1db35fb6..4fa620080d 100644
> --- a/package/pkg-cmake.mk
> +++ b/package/pkg-cmake.mk
> @@ -90,6 +90,8 @@ define $(2)_CONFIGURE_CMDS
>  	$$($$(PKG)_CONF_ENV) $$(BR2_CMAKE) $$($$(PKG)_SRCDIR) \
>  		-DCMAKE_TOOLCHAIN_FILE="$$(HOST_DIR)/share/buildroot/toolchainfile.cmake" \
>  		-DCMAKE_INSTALL_PREFIX="/usr" \
> +		-DCMAKE_PREFIX_PATH="$$(STAGING_DIR)/usr" \
> +		-DPKG_CONFIG_USE_CMAKE_PREFIX_PATH=ON \

But doesn't that needs to be in a separate patch? I mean, does it not
make sense opn its own?

[--SNIP--]
> diff --git a/package/pkg-meson.mk b/package/pkg-meson.mk
> index 0835e08e3a..de5817d5da 100644
> --- a/package/pkg-meson.mk
> +++ b/package/pkg-meson.mk
[--SNIP--]
> @@ -138,6 +138,7 @@ define $(2)_CONFIGURE_CMDS
>  	$$(MESON) \
>  		--prefix=/usr \
>  		--libdir=lib \
> +		--pkgconfig.relocatable \

Please explain what that means and why this is needed in the context of
a target package.

>  		--default-library=$(if $(BR2_STATIC_LIBS),static,shared) \
>  		--buildtype=$(if $(BR2_ENABLE_RUNTIME_DEBUG),debug,release) \
>  		--cross-file=$$($$(PKG)_SRCDIR)/build/cross-compilation.conf \
> @@ -156,10 +157,11 @@ define $(2)_CONFIGURE_CMDS
>  	mkdir -p $$($$(PKG)_SRCDIR)/build
>  	$$(HOST_CONFIGURE_OPTS) \
>  	$$($$(PKG)_CONF_ENV) $$(MESON) \
> -		--prefix=$$(HOST_DIR) \
> +		--prefix=/ \

It is very weird that host packages are configured with / as prefix, and
then installed in HOST_DIR set as DEST_DIR.

I guess this is working thanks to --pkgconfig.relocatable a few lines
below?

This must be explained in the commit log (and probably a little comment
above $(2)_CONFIGURE_CMDS for host packages.

>  		--libdir=lib \
> -		--sysconfdir=$$(HOST_DIR)/etc \
> -		--localstatedir=$$(HOST_DIR)/var \
> +		--pkgconfig.relocatable \
> +		--sysconfdir=etc \
> +		--localstatedir=var \

Ditto for etc and var?

So, to make it easier to follow, I'd change the ordering:

    --pkgconfig.relocatable \
    --prefix=/ \
    --sysconfdir=etc \
    --localstatedir=var \

Regards,
Yann E. MORIN.

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