[RFC PATCH v5 1/8] build-sys: Add rust feature option

[Manos Pitsidianakis <manos.pitsidianakis@linaro.org>]

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 +++++
 configure                     | 12 ++++++++++++
 meson.build                   | 17 ++++++++++++++++-
 Kconfig                       |  1 +
 Kconfig.host                  |  3 +++
 meson_options.txt             |  5 +++++
 rust/Kconfig                  |  0
 scripts/meson-buildoptions.sh |  3 +++
 8 files changed, 45 insertions(+), 1 deletion(-)
 create mode 100644 rust/Kconfig

diff --git a/MAINTAINERS b/MAINTAINERS
index 7d9811458c..d427f13b79 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4228,6 +4228,11 @@ 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/configure b/configure
index 019fcbd0ef..8476968b96 100755
--- a/configure
+++ b/configure
@@ -173,6 +173,7 @@ fi
 
 # default parameters
 container_engine="auto"
+have_rust="no"
 cpu=""
 cross_compile="no"
 cross_prefix=""
@@ -757,6 +758,15 @@ for opt do
   ;;
   --gdb=*) gdb_bin="$optarg"
   ;;
+  --enable-rust)
+    have_rust="yes" ;
+    meson_option_add -Dhave_rust=true
+  ;;
+  --disable-rust)
+    have_rust="no" ;
+    meson_option_add -Dhave_rust=false
+    meson_option_add -Ddisable_rust=true
+  ;;
   # everything else has the same name in configure and meson
   --*) meson_option_parse "$opt" "$optarg"
   ;;
@@ -874,6 +884,8 @@ Advanced options (experts only):
                            start the emulator (only use if you are including
                            desired devices in configs/devices/)
   --with-devices-ARCH=NAME override default configs/devices
+  --enable-rust            enable compilation of Rust code
+  --disable-rust           disable compilation of Rust code
   --enable-debug           enable common debug build options
   --cpu=CPU                Build for host CPU [$cpu]
   --disable-containers     don't use containers for cross-building
diff --git a/meson.build b/meson.build
index a1e51277b0..a3f346ab3c 100644
--- a/meson.build
+++ b/meson.build
@@ -70,6 +70,14 @@ if host_os == 'darwin' and \
   all_languages += ['objc']
   objc = meson.get_compiler('objc')
 endif
+if get_option('have_rust') and meson.version().version_compare('<1.0.0')
+  error('Rust support requires Meson version >=1.0.0')
+endif
+have_rust = false
+if not get_option('disable_rust') and add_languages('rust', required: get_option('have_rust'), native: false)
+  rustc = meson.get_compiler('rust')
+  have_rust = true
+endif
 
 dtrace = not_found
 stap = not_found
@@ -2119,6 +2127,7 @@ endif
 
 config_host_data = configuration_data()
 
+config_host_data.set('CONFIG_HAVE_RUST', have_rust)
 audio_drivers_selected = []
 if have_system
   audio_drivers_available = {
@@ -3038,7 +3047,8 @@ 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' ]
 
@@ -4242,6 +4252,11 @@ 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 fb6a24a2de..63ca7f46df 100644
--- a/Kconfig
+++ b/Kconfig
@@ -4,3 +4,4 @@ source accel/Kconfig
 source target/Kconfig
 source hw/Kconfig
 source semihosting/Kconfig
+source rust/Kconfig
diff --git a/Kconfig.host b/Kconfig.host
index 17f405004b..4ade7899d6 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
diff --git a/meson_options.txt b/meson_options.txt
index 0269fa0f16..9eef45f85b 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -371,3 +371,8 @@ 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('have_rust', type: 'boolean', value: false,
+       description: 'Have Rust support')
+option('disable_rust', type: 'boolean', value: false,
+       description: 'Disable Rust support')
diff --git a/rust/Kconfig b/rust/Kconfig
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
index c97079a38c..bb5854115a 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'
@@ -556,6 +557,8 @@ _meson_option_parse() {
     --enable-whpx) printf "%s" -Dwhpx=enabled ;;
     --disable-whpx) printf "%s" -Dwhpx=disabled ;;
     --x86-version=*) quote_sh "-Dx86_version=$2" ;;
+    --enable-with-rust) printf "%s" -Dhave_rust=true ;;
+    --disable-with-rust) printf "%s" -Dhave_rust=false ;;
     --enable-xen) printf "%s" -Dxen=enabled ;;
     --disable-xen) printf "%s" -Dxen=disabled ;;
     --enable-xen-pci-passthrough) printf "%s" -Dxen_pci_passthrough=enabled ;;
-- 
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