🐛 fix(maturin): build cross targets again

.github/workflows/build-maturin-wheels.yaml

@@ -133,10 +133,10 @@ jobs:
           maturin-version: ${{ needs.source.outputs.maturin-version }}
           target: ${{ matrix.target }}
           args: >-
-            -m ${{ inputs.package-path }}/Cargo.toml --locked --release --out dist --target-dir target --interpreter ${{ matrix.python || '3.15' }} ${{ matrix.args }}
+            -m ${{ inputs.package-path }}/Cargo.toml --locked --release --out dist --target-dir target ${{ matrix.python && format('--interpreter {0}', matrix.python) || '' }} ${{ matrix.args }}
           manylinux: ${{ matrix.manylinux || 'auto' }}
           docker-options: --env SOURCE_DATE_EPOCH
-          sccache: ${{ needs.source.outputs.release != 'true' }}
+          sccache: ${{ needs.source.outputs.release != 'true' && !startsWith(matrix.os, 'windows') }}
       - name: 🏗️ Run post-build command
         if: ${{ inputs.post-build-command != '' }}
         shell: bash

README.md

@@ -545,13 +545,15 @@ Each matrix entry takes these keys:
 - `os`: runner label, used as `runs-on`.
 - `target`: Rust target triple passed to maturin.
 - `artifact`: suffix of the uploaded `<package-name>-wheels-<artifact>` artifact.
-- `python`: space-separated interpreters for `--interpreter`; default `3.15`.
+- `python`: space-separated interpreters for `--interpreter`. Leave it out for cross targets, where maturin finds no
+  host interpreter; a native entry without it builds for the job's Python 3.15.
 - `manylinux`: manylinux or musllinux policy; default `auto`.
 - `args`: extra maturin arguments, such as `--zig`.
 
 `package-path` is the directory holding the package's `Cargo.toml`; the sdist is built from it. `release-build` defaults
-to `false`, but any tag ref runs in release mode too, so a tag caller can omit it. Release mode builds without sccache.
-`workflow_call` defaults cannot be expressions, so the workflow combines the two inside.
+to `false`, but any tag ref runs in release mode too, so a tag caller can omit it. Release mode and Windows entries
+build without sccache, which breaks MSVC builds of C dependencies. `workflow_call` defaults cannot be expressions, so
+the workflow combines the two inside.
 
 `pre-build-command` runs once in the source job from the checkout root, so every wheel job builds the same tree. Use it
 for a version bump, which must happen before the source artifact is written. `post-build-command` runs in each wheel job

changelog.d/+maturin-cross-targets.bugfix.md

@@ -0,0 +1,2 @@
+`build-maturin-wheels` passes `--interpreter` only for matrix entries that set `python`, so cross targets build again,
+and it no longer enables sccache on Windows, where it broke MSVC builds of C dependencies.

tests/build_maturin_wheels/test_workflow.py

@@ -42,15 +42,22 @@ def test_artifact_names_match_the_callers_names(workflow: JsonObject) -> None:
     }
 
 
-def test_release_mode_disables_sccache_for_tags_or_input(workflow: JsonObject) -> None:
+def test_sccache_is_off_for_releases_and_windows(workflow: JsonObject) -> None:
     assert at(workflow, "jobs", "source", "outputs", "release") == (
         "${{ inputs.release-build || startsWith(github.ref, 'refs/tags/') }}"
     )
     assert at(step(workflow, "build", "🏗️ Build wheels"), "with", "sccache") == (
-        "${{ needs.source.outputs.release != 'true' }}"
+        "${{ needs.source.outputs.release != 'true' && !startsWith(matrix.os, 'windows') }}"
     )
 
 
+def test_interpreter_is_passed_only_for_entries_that_name_one(workflow: JsonObject) -> None:
+    args = text(at(step(workflow, "build", "🏗️ Build wheels"), "with", "args"))
+
+    assert "${{ matrix.python && format('--interpreter {0}', matrix.python) || '' }}" in args
+    assert "'3.15'" not in args
+
+
 def test_post_build_command_runs_after_maturin_and_before_upload(workflow: JsonObject) -> None:
     names = [item["name"] for item in steps(workflow, "build")]