rust: new targets rustfmt and rustfmt-check

This is very similar to clippy, with different command line of course.
Also it can change files, so do not run it twice on the same file.

Signed-off-by: Paolo Bonzini <[email protected]>

docs/markdown/snippets/rustfmt.md

@@ -0,0 +1,6 @@
+## Meson can run "rustfmt" on Rust projects
+
+Meson now defines `rustfmt` and `rustfmt-check` targets if the project
+uses the Rust programming language.  The target runs rustfmt on all Rust
+sources, using the `rustfmt` program from the same Rust toolchain as the
+`rustc` compiler.

mesonbuild/backend/ninjabackend.py

@@ -3659,6 +3659,20 @@ def generate_clippy(self) -> None:
                 elem.add_dep(crate.target_name)
         self.add_build(elem)
 
+    def generate_rustfmt(self) -> None:
+        if not self.have_language('rust'):
+            return
+
+        for target, args in {'rustfmt': [], 'rustfmt-check': ['--check']}.items():
+            if target in self.all_outputs:
+                continue
+            cmd = self.environment.get_build_command() + \
+                ['--internal', 'rustfmt'] + args + [self.environment.build_dir]
+            elem = self.create_phony_target(target, 'CUSTOM_COMMAND', 'PHONY')
+            elem.add_item('COMMAND', cmd)
+            elem.add_item('pool', 'console')
+            self.add_build(elem)
+
     def generate_scanbuild(self) -> None:
         if not environment.detect_scanbuild():
             return
@@ -3727,6 +3741,7 @@ def generate_utils(self) -> None:
         self.generate_clangformat()
         self.generate_clangtidy()
         self.generate_clippy()
+        self.generate_rustfmt()
         self.generate_tags('etags', 'TAGS')
         self.generate_tags('ctags', 'ctags')
         self.generate_tags('cscope', 'cscope')

mesonbuild/compilers/rust.py

@@ -282,7 +282,7 @@ def get_assert_args(self, disable: bool, env: 'Environment') -> T.List[str]:
         action = "no" if disable else "yes"
         return ['-C', f'debug-assertions={action}', '-C', 'overflow-checks=no']
 
-    def get_rust_tool(self, name: str, env: Environment) -> T.List[str]:
+    def get_rust_tool(self, name: str, env: Environment, keep_args: bool = True) -> T.List[str]:
         if self.rustup_run_and_args:
             rustup_exelist, args = self.rustup_run_and_args
             # do not use extend so that exelist is copied
@@ -299,7 +299,7 @@ def get_rust_tool(self, name: str, env: Environment) -> T.List[str]:
         else:
             return []
 
-        return exelist + args
+        return exelist + args if keep_args else exelist
 
 
 class ClippyRustCompiler(RustCompiler):

mesonbuild/scripts/rustfmt.py

@@ -0,0 +1,59 @@
+# SPDX-License-Identifier: Apache-2.0
+# Copyright 2024 The Meson development team
+
+from __future__ import annotations
+import argparse
+import os
+import sys
+import typing as T
+
+from .run_tool import run_tool_on_targets, run_with_buffered_output
+from .. import build, mlog
+from ..mesonlib import MachineChoice
+
+if T.TYPE_CHECKING:
+    from ..compilers.rust import RustCompiler
+
+class Rustfmt:
+    def __init__(self, rustfmt: T.List[str], args: T.List[str]):
+        self.args = rustfmt + args
+        self.done: T.Set[str] = set()
+
+    def __call__(self, target: T.Dict[str, T.Any]) -> T.Iterable[T.Coroutine[T.Any, T.Any, int]]:
+        for src_block in target['target_sources']:
+            if src_block['language'] == 'rust':
+                file = src_block['sources'][0]
+                if file in self.done:
+                    continue
+                self.done.add(file)
+
+                cmdlist = list(self.args)
+                for arg in src_block['parameters']:
+                    if arg.startswith('--color=') or arg.startswith('--edition='):
+                        cmdlist.append(arg)
+
+                cmdlist.append(src_block['sources'][0])
+                yield run_with_buffered_output(cmdlist)
+
+def run(args: T.List[str]) -> int:
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--check', action='store_true')
+    parser.add_argument('builddir')
+    options = parser.parse_args(args)
+
+    os.chdir(options.builddir)
+    build_data = build.load(os.getcwd())
+
+    rustfmt: T.Optional[T.List[str]] = None
+    for machine in MachineChoice:
+        compilers = build_data.environment.coredata.compilers[machine]
+        if 'rust' in compilers:
+            compiler = T.cast('RustCompiler', compilers['rust'])
+            rustfmt = compiler.get_rust_tool('rustfmt', build_data.environment, False)
+            if rustfmt:
+                break
+    else:
+        mlog.error('rustfmt not found')
+        sys.exit(1)
+
+    return run_tool_on_targets(Rustfmt(rustfmt, ['--check'] if options.check else []))

unittests/allplatformstests.py

@@ -4884,6 +4884,26 @@ def output_name(name, type_):
                 with self.subTest(key='{}.{}'.format(data_type, file)):
                     self.assertEqual(res[data_type][file], details)
 
+    @skip_if_not_language('rust')
+    @unittest.skipIf(not shutil.which('rustfmt'), 'Test requires rustfmt')
+    def test_rustfmt(self) -> None:
+        if self.backend is not Backend.ninja:
+            raise unittest.SkipTest('Rust is only supported with ninja currently')
+        try:
+            with tempfile.TemporaryDirectory() as tmpdir:
+                testdir = self.copy_srcdir(os.path.join(self.rust_test_dir, '9 unit tests'))
+                self.init(testdir)
+                with self.assertRaises(subprocess.CalledProcessError) as cm:
+                    self.build('rustfmt-check')
+
+                self.build('rustfmt')
+                self.build('rustfmt-check')
+        except PermissionError:
+            # When run under Windows CI, something (virus scanner?)
+            # holds on to the git files so cleaning up the dir
+            # fails sometimes.
+            pass
+
     @skip_if_not_language('rust')
     @unittest.skipIf(not shutil.which('clippy-driver'), 'Test requires clippy-driver')
     def test_rust_clippy(self) -> None: