Add rustversion dependency to meson build

Author: dtolnay

.github/workflows/ci.yml

@@ -128,6 +128,7 @@ jobs:
         with:
           repository: mesonbuild/meson
           path: meson
+      - uses: dtolnay/rust-toolchain@nightly
       - run: sudo apt-get install lld ninja-build
       - run: meson/meson.py setup --native-file=tools/meson/native.ini build
       - run: meson/meson.py compile -C build

meson.build

@@ -16,6 +16,8 @@ add_project_arguments(
     language: 'cpp',
 )
 
+add_global_arguments('-Zunstable-options', language: 'rust', native: true)
+
 subdir('tools/meson')
 subdir('third-party')
 
@@ -34,6 +36,7 @@ cxxbridge_macro = rust.proc_macro(
     dependencies: [
         third_party['proc-macro2'],
         third_party['quote'],
+        third_party['rustversion'],
         third_party['syn'],
     ],
     sources: files('macro/src/lib.rs'),

subprojects/packagefiles/rustversion/meson.build

@@ -0,0 +1,48 @@
+project(
+    'rustversion',
+    'rust',
+    default_options: ['rust_std=2018'],
+    license: 'MIT OR Apache-2.0',
+    meson_version: '>= 1.3.0',
+    version: '1.0.18',
+)
+
+rust = import('rust')
+
+build = executable(
+    'build_script',
+    native: true,
+    sources: files('build/build.rs'),
+)
+
+rustc_args = custom_target(
+    command: [
+        find_program('python3'),
+        '@SOURCE_ROOT@/tools/meson/buildscript_run.py',
+        '--buildscript',
+        build,
+        '--manifest-dir',
+        '@CURRENT_SOURCE_DIR@',
+        '--rustc-wrapper',
+        '@BUILD_ROOT@/tools/meson/rustc_wrapper.sh',
+        '--out-dir',
+        '@PRIVATE_DIR@',
+        '--rustc-args',
+        '@OUTPUT@',
+    ],
+    env: {'HOST': 'x86_64-unknown-linux-gnu'},
+    # Hack: any extension other than .rs causes a failure "ERROR: Rust target
+    # rustversion contains a non-rust source file" below, and forces the use of
+    # `structured_sources` which would mean listing out every source file in the
+    # crate, instead of just the crate root lib.rs.
+    output: 'rustc_args.out.rs',
+)
+
+lib = rust.proc_macro(
+    'rustversion',
+    rust_args: ['@' + rustc_args.full_path()],
+    sources: [files('src/lib.rs'), rustc_args],
+)
+
+dep = declare_dependency(link_with: lib)
+meson.override_dependency('rustversion', dep)

subprojects/rustversion.wrap

@@ -0,0 +1,6 @@
+[wrap-file]
+directory = rustversion-1.0.18
+source_url = https://static.crates.io/crates/rustversion/1.0.18/download
+source_filename = rustversion-1.0.18.tar.gz
+source_hash = 0e819f2bc632f285be6d7cd36e25940d45b2391dd6d9b939e79de557f7014248
+patch_directory = rustversion

third-party/meson.build

@@ -1,5 +1,6 @@
 # Must be sorted topologically, not alphabetically.
 third_party = {
+    'rustversion': subproject('rustversion').get_variable('dep'),
     'unicode_ident': subproject('unicode-ident').get_variable('dep'),
     'proc-macro2': subproject('proc-macro2').get_variable('dep'),
     'quote': subproject('quote').get_variable('dep'),

tools/meson/buildscript_run.py

@@ -73,6 +73,7 @@ def main():
         cargo_rustc_cfg_match = cargo_rustc_cfg_pattern.match(line)
         if cargo_rustc_cfg_match:
             flags += "--cfg={}\n".format(cargo_rustc_cfg_match.group(1))
+    flags += "--env-set=OUT_DIR={}\n".format(os.path.abspath(args.out_dir))
     args.rustc_args.write(flags)