Merge pull request #1395 from dtolnay/edition2024

Make generated code compatible with Rust 2024 edition

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

BUCK

@@ -58,6 +58,7 @@ rust_library(
     deps = [
         "//third-party:proc-macro2",
         "//third-party:quote",
+        "//third-party:rustversion",
         "//third-party:syn",
     ],
 )

BUILD.bazel

@@ -54,6 +54,9 @@ rust_proc_macro(
     name = "cxxbridge-macro",
     srcs = glob(["macro/src/**/*.rs"]),
     edition = "2021",
+    proc_macro_deps = [
+        "@crates.io//:rustversion",
+    ],
     deps = [
         "@crates.io//:proc-macro2",
         "@crates.io//:quote",

MODULE.bazel.lock

@@ -23,6 +23,7 @@ experimental-enum-variants-from-header = ["clang-ast", "flate2", "memmap", "serd
 [dependencies]
 proc-macro2 = "1.0.74"
 quote = "1.0.35"
+rustversion = "1"
 syn = { version = "2.0.46", features = ["full"] }
 
 # optional dependencies:

macro/Cargo.toml

@@ -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'),

macro/src/expand.rs

@@ -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)

meson.build

@@ -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

subprojects/packagefiles/rustversion/meson.build

@@ -1,4 +1,3 @@
-#![forbid(unsafe_op_in_unsafe_fn)]
 #![allow(
     clippy::boxed_local,
     clippy::derive_partial_eq_without_eq,
@@ -15,6 +14,9 @@
     clippy::unnecessary_wraps,
     clippy::unused_self
 )]
+#![allow(unknown_lints)]
+#![warn(rust_2024_compatibility)]
+#![forbid(unsafe_op_in_unsafe_fn)]
 
 pub mod cast;
 pub mod module;
@@ -456,13 +458,15 @@ fn r_return_box() -> Box<R> {
 }
 
 fn r_return_unique_ptr() -> UniquePtr<ffi::C> {
+    #[allow(missing_unsafe_on_extern)]
     extern "C" {
         fn cxx_test_suite_get_unique_ptr() -> *mut ffi::C;
     }
     unsafe { UniquePtr::from_raw(cxx_test_suite_get_unique_ptr()) }
 }
 
 fn r_return_shared_ptr() -> SharedPtr<ffi::C> {
+    #[allow(missing_unsafe_on_extern)]
     extern "C" {
         fn cxx_test_suite_get_shared_ptr(repr: *mut SharedPtr<ffi::C>);
     }
@@ -501,6 +505,7 @@ fn r_return_rust_string() -> String {
 }
 
 fn r_return_unique_ptr_string() -> UniquePtr<CxxString> {
+    #[allow(missing_unsafe_on_extern)]
     extern "C" {
         fn cxx_test_suite_get_unique_ptr_string() -> *mut CxxString;
     }

subprojects/rustversion.wrap

@@ -12,5 +12,6 @@ clap = { version = "4", default-features = false, features = ["error-context", "
 codespan-reporting = "0.11.1"
 proc-macro2 = { version = "1.0.58", features = ["span-locations"] }
 quote = "1.0.4"
+rustversion = "1"
 scratch = "1"
 syn = { version = "2.0.1", features = ["full"] }