Add variants_mode: local support to get a variants file for package

README.md

@@ -34,6 +34,34 @@ package_name_mode: both
 
 Once users and downstream projects have migrated, switch to `new` to stop generating the compatibility packages. New ROS 1 package names use the `ros-` prefix; new ROS 2 package names use `ros2-`.
 
+## Variants mode
+
+The optional `variants_mode` setting controls how rattler-build receives the
+repository-level `conda_build_config.yaml`:
+
+- `global` (default) leaves generated recipes unchanged. Builds must pass the
+  root configuration explicitly, for example with
+  `rattler-build build ... -m ./conda_build_config.yaml`.
+- `local` generates a `variants.yaml` beside every `recipe.yaml`. Vinca converts
+  legacy comment selectors to v1 selectors and keeps only pins used by that
+  package. Builds must not pass the root configuration with `-m`, because an
+  explicit variant file takes precedence over the recipe-local file.
+
+```yaml
+variants_mode: local
+```
+
+Local mode requires `conda_build_config.yaml` next to `vinca.yaml`. Optional
+per-package additions or replacements can be declared in
+`pkg_additional_info.yaml`:
+
+```yaml
+my_ros_package:
+  variant_overrides:
+    c_stdlib_version:
+      - '2.28'
+```
+
 ## Configuring setup-pixi in generated workflows
 
 Generated GitHub Actions workflows use `prefix-dev/setup-pixi@v0` by default. Override the action version in `vinca.yaml` when needed:

vinca/configuration.py

@@ -22,6 +22,11 @@
 from vinca.resolve import get_conda_index
 from vinca.utils import add_package_name_variants
 from vinca.v1_selectors import evaluate_selectors
+from vinca.variants import (
+    VariantsMode,
+    convert_v0_variant_selectors,
+    get_variants_mode,
+)
 
 _PATCH_PLATFORMS = ("osx", "linux", "win", "emscripten")
 
@@ -105,6 +110,7 @@ def read_vinca_yaml(filepath: str | Path, target_platform: str) -> dict[str, Any
     config_dir = filepath.parent
     vinca_conf = _load_selected_yaml(filepath, target_platform)
     vinca_conf["package_name_mode"] = get_package_name_mode(vinca_conf).value
+    vinca_conf["variants_mode"] = get_variants_mode(vinca_conf).value
     vinca_conf["conda_index"] = _normalize_conda_indexes(vinca_conf["conda_index"])
 
     patch_dir = Path(vinca_conf["patch_dir"]).absolute()
@@ -133,6 +139,17 @@ def read_vinca_yaml(filepath: str | Path, target_platform: str) -> dict[str, Any
         else {}
     )
 
+    vinca_conf["_variant_config"] = {}
+    if get_variants_mode(vinca_conf) is VariantsMode.LOCAL:
+        variant_config_path = config_dir / "conda_build_config.yaml"
+        if not variant_config_path.is_file():
+            raise FileNotFoundError(
+                "variants_mode 'local' requires conda_build_config.yaml next to vinca.yaml"
+            )
+        vinca_conf["_variant_config"] = convert_v0_variant_selectors(
+            _load_yaml(variant_config_path) or {}
+        )
+
     snapshot, additional = read_snapshot(vinca_conf)
     vinca_conf["_snapshot"] = snapshot or {}
     vinca_conf["_additional_packages_snapshot"] = additional or {}

vinca/template.py

@@ -14,6 +14,7 @@
     get_pkg_additional_info,
     get_pkg_build_number,
 )
+from vinca.variants import VariantsMode, get_recipe_variants, get_variants_mode
 
 TEMPLATE = """\
 # yaml-language-server: $schema=https://raw.githubusercontent.com/prefix-dev/recipe-format/main/schema.json
@@ -165,6 +166,11 @@ def write_recipe(source, outputs, vinca_conf, distro, single_file=True):
             with open(recipe_dir / "recipe.yaml", "w") as stream:
                 file.dump(meta, stream)
 
+            if get_variants_mode(vinca_conf) is VariantsMode.LOCAL:
+                variants = get_recipe_variants(meta, package_shortname, vinca_conf)
+                with open(recipe_dir / "variants.yaml", "w") as stream:
+                    file.dump(variants, stream)
+
             if meta.get("source") and meta["source"].get("patches"):
                 for p in meta["source"]["patches"]:
                     patch_dir, _ = os.path.split(p)

vinca/test_configuration.py

@@ -1,3 +1,5 @@
+import pytest
+
 from vinca.configuration import read_snapshot, read_vinca_yaml
 
 
@@ -31,6 +33,59 @@ def test_read_vinca_yaml_discovers_companion_files(tmp_path, monkeypatch):
     assert config["_test_folders"]["demo"] == tests / "demo"
     assert config["_pkg_additional_info"]["demo"]["build_number"] == 2
     assert config["depmods"] == {"demo": {}}
+    assert config["variants_mode"] == "global"
+    assert config["_variant_config"] == {}
+
+
+def test_read_vinca_yaml_loads_local_variant_config(tmp_path, monkeypatch):
+    monkeypatch.chdir(tmp_path)
+    (tmp_path / "patches").mkdir()
+    (tmp_path / "vinca.yaml").write_text(
+        "ros_distro: humble\nconda_index: []\npatch_dir: patches\nvariants_mode: local\n"
+    )
+    (tmp_path / "conda_build_config.yaml").write_text(
+        "c_compiler:\n"
+        "  - gcc  # [linux]\n"
+        "  - clang  # [osx]\n"
+        "c_compiler_version:  # [unix]\n"
+        "  - 14  # [linux]\n"
+        "  - 19  # [osx]\n"
+    )
+
+    config = read_vinca_yaml(tmp_path / "vinca.yaml", "linux-64")
+
+    assert config["variants_mode"] == "local"
+    assert config["_variant_config"] == {
+        "c_compiler": [
+            {"if": "linux", "then": "gcc"},
+            {"if": "osx", "then": "clang"},
+        ],
+        "c_compiler_version": [
+            {"if": "(unix) and (linux)", "then": 14},
+            {"if": "(unix) and (osx)", "then": 19},
+        ],
+    }
+
+
+def test_read_vinca_yaml_rejects_invalid_variants_mode(tmp_path, monkeypatch):
+    monkeypatch.chdir(tmp_path)
+    (tmp_path / "vinca.yaml").write_text(
+        "ros_distro: humble\nconda_index: []\npatch_dir: patches\nvariants_mode: other\n"
+    )
+
+    with pytest.raises(ValueError, match="Invalid variants_mode 'other'"):
+        read_vinca_yaml(tmp_path / "vinca.yaml", "linux-64")
+
+
+def test_read_vinca_yaml_requires_config_for_local_pinning(tmp_path, monkeypatch):
+    monkeypatch.chdir(tmp_path)
+    (tmp_path / "patches").mkdir()
+    (tmp_path / "vinca.yaml").write_text(
+        "ros_distro: humble\nconda_index: []\npatch_dir: patches\nvariants_mode: local\n"
+    )
+
+    with pytest.raises(FileNotFoundError, match="requires conda_build_config.yaml"):
+        read_vinca_yaml(tmp_path / "vinca.yaml", "linux-64")
 
 
 def test_read_snapshot_merges_additional_packages(tmp_path):

vinca/test_template.py

@@ -0,0 +1,52 @@
+from pathlib import Path
+
+from ruamel.yaml import YAML
+
+from vinca.template import write_recipe
+
+
+class FakeDistro:
+    def get_package_prefix(self):
+        return "ros2"
+
+    def get_legacy_package_prefix(self):
+        return "ros-jazzy"
+
+
+def config(variants_mode):
+    return {
+        "ros_distro": "jazzy",
+        "package_name_mode": "legacy",
+        "variants_mode": variants_mode,
+        "build_number": 0,
+        "_tests": {},
+        "_test_folders": {},
+        "_additional_packages_snapshot": {},
+        "_pkg_additional_info": {},
+        "_variant_config": {"python": ["3.12"], "unused": ["1"]},
+    }
+
+
+def output():
+    return {
+        "package": {"name": "ros-jazzy-demo", "version": "1.0"},
+        "requirements": {"host": ["python"], "run": ["python"]},
+        "build": {"script": ""},
+    }
+
+
+def test_write_recipe_emits_pruned_variants_in_local_mode(tmp_path, monkeypatch):
+    monkeypatch.chdir(tmp_path)
+
+    write_recipe({}, [output()], config("local"), FakeDistro(), single_file=False)
+
+    variants_path = Path("recipes/ros-jazzy-demo/variants.yaml")
+    assert YAML(typ="safe").load(variants_path) == {"python": ["3.12"]}
+
+
+def test_write_recipe_does_not_emit_variants_in_global_mode(tmp_path, monkeypatch):
+    monkeypatch.chdir(tmp_path)
+
+    write_recipe({}, [output()], config("global"), FakeDistro(), single_file=False)
+
+    assert not Path("recipes/ros-jazzy-demo/variants.yaml").exists()

vinca/test_variants.py

@@ -0,0 +1,111 @@
+from vinca.variants import get_recipe_variants
+
+
+def test_get_recipe_variants_prunes_to_recipe_dependencies_and_expressions():
+    recipe = {
+        "requirements": {
+            "build": ["${{ compiler('cxx') }}", "${{ stdlib('c') }}"],
+            "host": ["python", "libfoo >=1"],
+            "run": ["python"],
+        },
+        "build": {
+            "script": "echo ${{ cxx_compiler_version }}",
+        },
+    }
+    config = {
+        "_variant_config": {
+            "python": ["3.12.* *_cpython"],
+            "python_impl": ["cpython"],
+            "libfoo": ["2"],
+            "unused": ["1"],
+            "c_compiler": ["gcc"],
+            "c_compiler_version": ["14"],
+            "cxx_compiler": ["gxx"],
+            "cxx_compiler_version": ["14"],
+            "c_stdlib": ["sysroot"],
+            "c_stdlib_version": ["2.17"],
+            "zip_keys": [["python", "python_impl"], ["libfoo", "unused"]],
+            "pin_run_as_build": {
+                "python": {"max_pin": "x.x"},
+                "unused": {"max_pin": "x"},
+            },
+        },
+        "_pkg_additional_info": {},
+    }
+
+    assert get_recipe_variants(recipe, "demo", config) == {
+        "python": ["3.12.* *_cpython"],
+        "libfoo": ["2"],
+        "cxx_compiler": ["gxx"],
+        "cxx_compiler_version": ["14"],
+        "c_stdlib": ["sysroot"],
+        "c_stdlib_version": ["2.17"],
+        "pin_run_as_build": {"python": {"max_pin": "x.x"}},
+    }
+
+
+def test_get_recipe_variants_merges_and_keeps_package_overrides():
+    config = {
+        "_variant_config": {
+            "python": ["3.12.* *_cpython"],
+            "unused": ["1"],
+        },
+        "_pkg_additional_info": {
+            "demo": {
+                "variant_overrides": {
+                    "python": ["3.13.* *_cpython"],
+                    "custom_feature": [True],
+                }
+            }
+        },
+    }
+
+    assert get_recipe_variants(
+        {"requirements": {"host": ["python"]}}, "demo", config
+    ) == {
+        "python": ["3.13.* *_cpython"],
+        "custom_feature": [True],
+    }
+
+
+def test_get_recipe_variants_trims_zip_keys_to_used_members():
+    config = {
+        "_variant_config": {
+            "python": ["3.12", "3.13"],
+            "numpy": ["1", "2"],
+            "python_impl": ["cpython", "cpython"],
+            "zip_keys": [["python", "numpy", "python_impl"]],
+        },
+        "_pkg_additional_info": {},
+    }
+
+    assert get_recipe_variants(
+        {"requirements": {"host": ["python", "numpy"]}}, "demo", config
+    ) == {
+        "python": ["3.12", "3.13"],
+        "numpy": ["1", "2"],
+        "zip_keys": [["python", "numpy"]],
+    }
+
+
+def test_get_recipe_variants_uses_test_requirements_not_test_commands():
+    config = {
+        "_variant_config": {
+            "python": ["3.12"],
+            "pytest": ["8"],
+        },
+        "_pkg_additional_info": {},
+    }
+
+    assert get_recipe_variants(
+        {
+            "tests": [
+                {
+                    "script": ["python -c 'print(1)'"],
+                    "requirements": {"run": ["pytest"]},
+                }
+            ]
+        },
+        "demo",
+        config,
+    ) == {"pytest": ["8"]}