Re: [PATCH RESEND v9 2/9] build-sys: Add rust feature option

["Alex Bennée" <alex.bennee@linaro.org>]

Manos Pitsidianakis <manos.pitsidianakis@linaro.org> writes:

> Add rust feature in meson.build, configure, to prepare for adding Rust
> code in the followup commits.
>
> Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
> ---
>  MAINTAINERS                   |  5 +++++
>  meson.build                   | 25 ++++++++++++++++++++++++-
>  Kconfig                       |  1 +
>  Kconfig.host                  |  3 +++
>  meson_options.txt             |  3 +++
>  rust/Kconfig                  |  0
>  scripts/meson-buildoptions.sh |  3 +++
>  7 files changed, 39 insertions(+), 1 deletion(-)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 3584d6a6c6da9a3210150534d640d29ddf329dce..0bc8e515daf7e63320620b52b42a799b99dbe035 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -4243,6 +4243,11 @@ F: docs/sphinx/
>  F: docs/_templates/
>  F: docs/devel/docs.rst
>  
> +Rust build system integration
> +M: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
> +S: Maintained
> +F: rust/Kconfig
> +
>  Miscellaneous
>  -------------
>  Performance Tools and Tests
> diff --git a/meson.build b/meson.build
> index 7eb4b8a41c0a667cacf693cfa2764f326ba72b1f..67eb4eda649d5f0566de2b75466b5a9d9ca87ab4 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -70,6 +70,22 @@ if host_os == 'darwin' and \
>    all_languages += ['objc']
>    objc = meson.get_compiler('objc')
>  endif
> +if get_option('rust').enabled() and meson.version().version_compare('<1.0.0')
> +  error('Rust support requires Meson version >=1.0.0')
> +endif

Isn't this test obsolete as patch 1 ensures we have at least 1.50 anyway? 

> +have_rust = false
> +if not get_option('rust').disabled() and add_languages('rust', required: get_option('rust'), native: false)
> +  rustc = meson.get_compiler('rust')
> +  have_rust = true
> +  if rustc.version().version_compare('<1.80.0')
> +    if get_option('rust').enabled()
> +      error('rustc version ' + rustc.version() + ' is unsupported: Please upgrade to at least 1.80.0')
> +    else
> +      warning('rustc version ' + rustc.version() + ' is unsupported: Disabling Rust compilation. Please upgrade to at least 1.80.0 to use Rust.')
> +      have_rust = false
> +    endif
> +  endif
> +endif
>  
>  dtrace = not_found
>  stap = not_found
> @@ -2131,6 +2147,7 @@ endif
>  
>  config_host_data = configuration_data()
>  
> +config_host_data.set('CONFIG_HAVE_RUST', have_rust)
>  audio_drivers_selected = []
>  if have_system
>    audio_drivers_available = {
> @@ -3076,7 +3093,8 @@ host_kconfig = \
>    (host_os == 'linux' ? ['CONFIG_LINUX=y'] : []) + \
>    (multiprocess_allowed ? ['CONFIG_MULTIPROCESS_ALLOWED=y'] : []) + \
>    (vfio_user_server_allowed ? ['CONFIG_VFIO_USER_SERVER_ALLOWED=y'] : []) + \
> -  (hv_balloon ? ['CONFIG_HV_BALLOON_POSSIBLE=y'] : [])
> +  (hv_balloon ? ['CONFIG_HV_BALLOON_POSSIBLE=y'] : []) + \
> +  (have_rust ? ['CONFIG_HAVE_RUST=y'] : [])
>  
>  ignored = [ 'TARGET_XML_FILES', 'TARGET_ABI_DIR', 'TARGET_ARCH' ]
>  
> @@ -4287,6 +4305,11 @@ if 'objc' in all_languages
>  else
>    summary_info += {'Objective-C compiler': false}
>  endif
> +summary_info += {'Rust support':      have_rust}
> +if have_rust
> +  summary_info += {'rustc version':      rustc.version()}
> +  summary_info += {'rustc':      ' '.join(rustc.cmd_array())}
> +endif
>  option_cflags = (get_option('debug') ? ['-g'] : [])
>  if get_option('optimization') != 'plain'
>    option_cflags += ['-O' + get_option('optimization')]
> diff --git a/Kconfig b/Kconfig
> index fb6a24a2de8c3ff11d4ee432d65ad000ba9d6c4d..63ca7f46df788144864b26ef5a64b29ad6547435 100644
> --- a/Kconfig
> +++ b/Kconfig
> @@ -4,3 +4,4 @@ source accel/Kconfig
>  source target/Kconfig
>  source hw/Kconfig
>  source semihosting/Kconfig
> +source rust/Kconfig

I was wondering if we should call out the directory structure in
docs/devel but we don't currently. docs/devel/build-system.rst is
probably the wrong place for it so maybe we need a new section for code
layout. Anyway not a problem for this patch.

> diff --git a/Kconfig.host b/Kconfig.host
> index 17f405004b3bc765890688304322a1937ca8c01c..4ade7899d67a5ed91928f8ee1e287f5ba3331949 100644
> --- a/Kconfig.host
> +++ b/Kconfig.host
> @@ -52,3 +52,6 @@ config VFIO_USER_SERVER_ALLOWED
>  
>  config HV_BALLOON_POSSIBLE
>      bool
> +
> +config HAVE_RUST
> +    bool

Not this patches fault but the top of this Kconfig states:

  # These are "proxy" symbols used to pass config-host.mak values
  # down to Kconfig.  See also kconfig_external_symbols in
  # meson.build: these two need to be kept in sync.

but that was updated in 0a18911074 (meson: cleanup Kconfig.host
handling) and I can see host_kconfig has been updated. It would be nice
to put a patch in before just cleaning up that comment.


> diff --git a/meson_options.txt b/meson_options.txt
> index 0269fa0f16ed6b6f734fcefa2cfa94aa029fa837..fa94a5ce97bb14ab108e21cccb651923ac6a58f8 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -371,3 +371,6 @@ option('hexagon_idef_parser', type : 'boolean', value : true,
>  
>  option('x86_version', type : 'combo', choices : ['0', '1', '2', '3', '4'], value: '1',
>         description: 'tweak required x86_64 architecture version beyond compiler default')
> +
> +option('rust', type: 'feature', value: 'auto',
> +       description: 'Rust support')
> diff --git a/rust/Kconfig b/rust/Kconfig
> new file mode 100644
> index 0000000000000000000000000000000000000000..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
> diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
> index c97079a38c9e4ed24a0fe9b44e492b7108481048..5e8a225a6b343cf506950a3146af718d52a6c1a0 100644
> --- a/scripts/meson-buildoptions.sh
> +++ b/scripts/meson-buildoptions.sh
> @@ -170,6 +170,7 @@ meson_options_help() {
>    printf "%s\n" '  rbd             Ceph block device driver'
>    printf "%s\n" '  rdma            Enable RDMA-based migration'
>    printf "%s\n" '  replication     replication support'
> +  printf "%s\n" '  rust            Rust support'
>    printf "%s\n" '  rutabaga-gfx    rutabaga_gfx support'
>    printf "%s\n" '  sdl             SDL user interface'
>    printf "%s\n" '  sdl-image       SDL Image support for icons'
> @@ -452,6 +453,8 @@ _meson_option_parse() {
>      --disable-replication) printf "%s" -Dreplication=disabled ;;
>      --enable-rng-none) printf "%s" -Drng_none=true ;;
>      --disable-rng-none) printf "%s" -Drng_none=false ;;
> +    --enable-rust) printf "%s" -Drust=enabled ;;
> +    --disable-rust) printf "%s" -Drust=disabled ;;
>      --enable-rutabaga-gfx) printf "%s" -Drutabaga_gfx=enabled ;;
>      --disable-rutabaga-gfx) printf "%s" -Drutabaga_gfx=disabled ;;
>      --enable-safe-stack) printf "%s" -Dsafe_stack=true ;;

Without the unneeded version check:

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro