Let an extension be named apart from its Cargo artifact

hatch_rs/structs.py

@@ -451,6 +451,11 @@ class RustArtifactConfig(BaseModel):
     cargo_target_kind: CargoTargetKind | None = Field(default=None, alias="cargo-target-kind", description="Cargo target selector kind.")
     cargo_target: str | None = Field(default=None, alias="cargo-target", description="Cargo target selector name.")
     crate_type: str = Field(default="cdylib", alias="crate-type", description="Rust crate type to pass through to rustc.")
+    python_extension_name: str | None = Field(
+        default=None,
+        alias="python-extension-name",
+        description="Module stem for {python_extension_name}, when the importable name differs from the Cargo artifact name.",
+    )
     install_scheme: InstallScheme = Field(
         default="package",
         alias="install-scheme",
@@ -1029,7 +1034,8 @@ def _format_destination(
         import_library: str = "",
     ) -> Path:
         artifact = planned_artifact.artifact
-        python_extension = python_extension_name(_cargo_artifact_stem(source), abi3=self.abi3, platform=planned_artifact.resolved_target.platform)
+        extension_stem = artifact.python_extension_name or _cargo_artifact_stem(source)
+        python_extension = python_extension_name(extension_stem, abi3=self.abi3, platform=planned_artifact.resolved_target.platform)
         values = {
             "module": self.module,
             "target": planned_artifact.resolved_target.triple,

hatch_rs/tests/test_structs.py

@@ -156,6 +156,34 @@ def test_executable_name(platform: str, expected: str):
     assert executable_name("mycli", platform=platform) == expected
 
 
+def test_python_extension_name_overrides_cargo_artifact_stem(tmp_path):
+    # The cdylib is named apart from the core library it links, so the two do
+    # not collide in target/, but it still has to import under the module name.
+    plan = HatchRustBuildPlan(
+        module="project",
+        path=tmp_path,
+        target="x86_64-unknown-linux-gnu",
+        artifacts=[
+            {
+                "name": "project_ext",
+                "python-extension-name": "project",
+                "destination": "{module}/{python_extension_name}",
+            }
+        ],
+    )
+    plan.generate()
+    planned_artifact = plan._artifact_plans[0]
+    source = tmp_path / "target" / "x86_64-unknown-linux-gnu" / "release" / "libproject_ext.so"
+    source.parent.mkdir(parents=True)
+    source.write_bytes(b"extension")
+
+    plan._copy_outputs(planned_artifact, build_root=tmp_path)
+
+    copied = tmp_path / "project" / "project.so"
+    assert copied.read_bytes() == b"extension"
+    assert plan.libraries == ["project/project.so"]
+
+
 def test_build_plan_generates_cargo_invocation(tmp_path):
     plan = HatchRustBuildPlan(module="project", path=tmp_path, target="x86_64-apple-darwin")