Allow building the same crate for both machines

docs/markdown/Rust.md

@@ -98,3 +98,11 @@ target is a proc macro or dylib, or it depends on a dylib, in which case [`-C
 prefer-dynamic`](https://doc.rust-lang.org/rustc/codegen-options/index.html#prefer-dynamic)
 will be passed to the Rust compiler, and the standard libraries will be
 dynamically linked.
+
+## Multiple targets for the same crate name
+
+For library targets that have `rust_abi: 'rust'`, the crate name is derived from the
+target name.  First, dashes, spaces and dots are replaced with underscores.  Second,
+*since 1.10.0* anything after the first `+` is dropped.  This allows creating multiple
+targets for the same crate name, for example when the same crate is built multiple
+times with different features, or for both the build and the host machine.

mesonbuild/backend/ninjabackend.py

@@ -1946,11 +1946,17 @@ def _add_rust_project_entry(self, name: str, main_rust_file: str, args: Compiler
 
         self.rust_crates[name] = crate
 
-    def _get_rust_dependency_name(self, target: build.BuildTarget, dependency: LibTypes) -> str:
-        # Convert crate names with dashes to underscores by default like
-        # cargo does as dashes can't be used as parts of identifiers
-        # in Rust
-        return target.rust_dependency_map.get(dependency.name, dependency.name).replace('-', '_')
+    @staticmethod
+    def _get_rust_crate_name(target_name: str) -> str:
+        # Rustc replaces - with _. spaces or dots are not allowed, so we replace them with underscores
+        # Also +SUFFIX is dropped, which can be used to distinguish host from build crates
+        crate_name = target_name.replace('-', '_').replace(' ', '_').replace('.', '_')
+        return crate_name.split('+', 1)[0]
+
+    @staticmethod
+    def _get_rust_dependency_name(target: build.BuildTarget, dependency: LibTypes) -> str:
+        crate_name_raw = target.rust_dependency_map.get(dependency.name, dependency.name)
+        return NinjaBackend._get_rust_crate_name(crate_name_raw)
 
     def generate_rust_sources(self, target: build.BuildTarget) -> T.Tuple[T.List[str], str]:
         orderdeps: T.List[str] = []
@@ -2025,8 +2031,7 @@ def get_rust_compiler_args(self, target: build.BuildTarget, rustc: Compiler, src
             args.extend(rustc.get_linker_always_args())
 
         args += self.generate_basic_compiler_args(target, rustc)
-        # Rustc replaces - with _. spaces or dots are not allowed, so we replace them with underscores
-        args += ['--crate-name', target.name.replace('-', '_').replace(' ', '_').replace('.', '_')]
+        args += ['--crate-name', self._get_rust_crate_name(target.name)]
         if depfile:
             args += rustc.get_dependency_gen_args(target_name, depfile)
         args += rustc.get_output_args(target_name)

test cases/rust/30 both machines/lib.rs

@@ -0,0 +1,3 @@
+pub fn answer() -> u32 {
+    42
+}

test cases/rust/30 both machines/meson.build

@@ -0,0 +1,36 @@
+project(
+  'testproj',
+  'rust',
+  version : '0.1',
+  meson_version : '>= 1.9.0',
+  default_options : ['rust_std=2021'],
+)
+
+lib_host = static_library(
+  'lib',
+  'lib.rs',
+  rust_abi: 'rust'
+)
+
+lib_build = static_library(
+  'lib+build',
+  'lib.rs',
+  rust_abi: 'rust',
+  native: true,
+)
+
+exe_host = executable(
+  'test-host',
+  'test.rs',
+  link_with: lib_host,
+)
+
+exe_build = executable(
+  'test-build',
+  'test.rs',
+  link_with: lib_build,
+  native: true,
+)
+
+test('host', exe_host)
+test('build', exe_build)

test cases/rust/30 both machines/test.rs

@@ -0,0 +1,5 @@
+use lib::answer;
+
+fn main() {
+    println!("The answer is {}.\n", answer());
+}