meson: add optional Rust bindings build

meson.build

@@ -208,6 +208,48 @@ if get_option('c').enabled()
     endif
 endif
 
+rust_option = get_option('rust').require(
+    get_option('c').enabled(),
+    error_message: 'rust requires c',
+).require(
+    get_option('default_library') != 'static',
+    error_message: 'rust requires shared libraries',
+)
+if rust_option.allowed()
+    cargo = find_program('cargo', required: rust_option)
+    if cargo.found()
+        rust_env = environment()
+        rust_env.prepend('LIBRARY_PATH', meson.current_build_dir())
+        rust_env.prepend('LD_LIBRARY_PATH', meson.current_build_dir())
+        rust_env.prepend('DYLD_LIBRARY_PATH', meson.current_build_dir())
+        rust_env.prepend('PATH', meson.current_build_dir())
+        cargo_args = [
+            '--manifest-path', meson.current_source_dir() / 'rust/Cargo.toml',
+            '--target-dir', meson.current_build_dir() / 'rust',
+        ]
+        rust_build = custom_target(
+            'rust-bindings',
+            output: 'rust-build.json',
+            command: [cargo, 'build', '--lib', '--examples', '--message-format=json-render-diagnostics'] + cargo_args,
+            env: rust_env,
+            depends: opendht_c,
+            capture: true,
+            build_by_default: true,
+            build_always_stale: true,
+        )
+        if get_option('tests').enabled()
+            test(
+                'Rust',
+                cargo,
+                args: ['test'] + cargo_args,
+                env: rust_env,
+                depends: rust_build,
+                timeout: 120,
+            )
+        endif
+    endif
+endif
+
 if get_option('python').require(
     get_option('indexation').enabled(),
     error_message: 'python requires indexation',

meson.options

@@ -4,6 +4,7 @@ option('push_notifications', type : 'feature', value : 'disabled')
 option('peer_discovery', type : 'feature', value : 'enabled')
 option('tools', type : 'feature', value : 'enabled')
 option('c', type : 'feature', value : 'enabled')
+option('rust', type : 'feature', value : 'disabled')
 option('indexation', type : 'feature', value : 'enabled')
 option('python', type : 'feature', value : 'enabled')
 option('tests', type : 'feature', value : 'enabled')