cargo: autodetect patch directory

Many crates that have a build.rs will usually require an overlay
with the translated meson/meson.build file.  To avoid having to
create a .wrap file, when parsing Cargo.lock autodetect a directory
in subproject/packagefiles/ and add it as the patch_directory.

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

Author: bonzini

docs/markdown/Wrap-dependency-system-manual.md

@@ -364,9 +364,13 @@ Some naming conventions need to be respected:
 - The `features` variable is pre-defined and contains the list of features enabled
   on this crate.
 
-Since *1.5.0* Cargo wraps can also be provided with `Cargo.lock` file at the root
-of (sub)project source tree. Meson will automatically load that file and convert
-it into a series of wraps definitions.
+Since *1.5.0* Cargo wraps can also be provided with `Cargo.lock` file at the
+root of (sub)project source tree. Meson will automatically load that file, looking
+for crates found on `crates.io` or in a git repository, and will convert those
+crates into a series of wraps definitions.  Since *1.11.0* the overlay directory
+(`patch_directory`) is automatically detected, using the same directory as the
+dependency name for `crates.io` URLs, and the final component of the URL
+(possibly with the `.git` suffix removed) for "git" URLs.
 
 Since *1.10.0* Workspace Cargo.toml are supported. For the time being it is
 recommended to regroup all Cargo dependencies inside a single workspace invoked

mesonbuild/cargo/interpreter.py

@@ -819,6 +819,7 @@ def load_cargo_lock(filename: str, subproject_dir: str) -> T.Optional[CargoLock]
         toml = load_toml(filename)
         raw_cargolock = T.cast('raw.CargoLock', toml)
         cargolock = CargoLock.from_raw(raw_cargolock)
+        packagefiles_dir = os.path.join(subproject_dir, 'packagefiles')
         wraps: T.Dict[str, PackageDefinition] = {}
         for package in cargolock.package:
             meson_depname = _dependency_name(package.name, version.api(package.version))
@@ -832,6 +833,7 @@ def load_cargo_lock(filename: str, subproject_dir: str) -> T.Optional[CargoLock]
                 url = f'https://crates.io/api/v1/crates/{package.name}/{package.version}/download'
                 directory = f'{package.name}-{package.version}'
                 name = meson_depname
+                wrap_type = 'file'
                 cfg = {
                     'directory': directory,
                     'source_url': url,
@@ -842,17 +844,19 @@ def load_cargo_lock(filename: str, subproject_dir: str) -> T.Optional[CargoLock]
             elif package.source.startswith('git+'):
                 url, revision, directory = _parse_git_url(package.source)
                 name = directory
+                wrap_type = 'git'
                 cfg = {
                     'url': url,
                     'revision': revision,
                     'method': 'cargo',
                 }
-                wraps[directory].add_provided_dep(meson_depname)
             else:
                 mlog.warning(f'Unsupported source URL in {filename}: {package.source}')
                 continue
+            if os.path.isdir(os.path.join(packagefiles_dir, name)):
+                cfg['patch_directory'] = name
             if directory not in wraps:
-                wraps[directory] = PackageDefinition.from_values(name, subproject_dir, 'file', cfg)
+                wraps[directory] = PackageDefinition.from_values(name, subproject_dir, wrap_type, cfg)
             wraps[directory].add_provided_dep(meson_depname)
         cargolock.wraps = {w.name: w for w in wraps.values()}
         return cargolock