Merge pull request #2039 from conda-forge/lint-pip

feat: add linting for pip build backend

conda_smithy/lint_recipe.py

@@ -1,3 +1,4 @@
+import copy
 import json
 import os
 import sys
@@ -11,11 +12,17 @@
 import github
 import jsonschema
 import requests
+from conda_build.metadata import (
+    ensure_valid_license_family,
+)
+from rattler_build_conda_compat import loader as rattler_loader
 from ruamel.yaml.constructor import DuplicateKeyError
 
+from conda_smithy.configure_feedstock import _read_forge_config
 from conda_smithy.linter import conda_recipe_v1_linter
 from conda_smithy.linter.hints import (
     hint_check_spdx,
+    hint_pip_no_build_backend,
     hint_pip_usage,
     hint_shellcheck_usage,
     hint_suggest_noarch,
@@ -58,19 +65,8 @@
     RATTLER_BUILD_TOOL,
     find_local_config_file,
     get_section,
+    load_linter_toml_metdata,
 )
-
-if sys.version_info[:2] < (3, 11):
-    import tomli as tomllib
-else:
-    import tomllib
-
-from conda_build.metadata import (
-    ensure_valid_license_family,
-)
-from rattler_build_conda_compat import loader as rattler_loader
-
-from conda_smithy.configure_feedstock import _read_forge_config
 from conda_smithy.utils import get_yaml, render_meta_yaml
 from conda_smithy.validate_schema import validate_json_schema
 
@@ -499,9 +495,10 @@ def run_conda_forge_specific(
 
     # 5: Package-specific hints
     # (e.g. do not depend on matplotlib, only matplotlib-base)
-    build_reqs = requirements_section.get("build") or []
-    host_reqs = requirements_section.get("host") or []
-    run_reqs = requirements_section.get("run") or []
+    # we use a copy here since the += below mofiies the original list
+    build_reqs = copy.deepcopy(requirements_section.get("build") or [])
+    host_reqs = copy.deepcopy(requirements_section.get("host") or [])
+    run_reqs = copy.deepcopy(requirements_section.get("run") or [])
     for out in outputs_section:
         if recipe_version == 1:
             output_requirements = rattler_loader.load_all_requirements(out)
@@ -517,14 +514,7 @@ def run_conda_forge_specific(
             else:
                 run_reqs += _req
 
-    hints_toml_url = "https://raw.githubusercontent.com/conda-forge/conda-forge-pinning-feedstock/main/recipe/linter_hints/hints.toml"
-    hints_toml_req = requests.get(hints_toml_url)
-    if hints_toml_req.status_code != 200:
-        # too bad, but not important enough to throw an error;
-        # linter will rerun on the next commit anyway
-        return
-    hints_toml_str = hints_toml_req.content.decode("utf-8")
-    specific_hints = tomllib.loads(hints_toml_str)["hints"]
+    specific_hints = (load_linter_toml_metdata() or {}).get("hints", [])
 
     for rq in build_reqs + host_reqs + run_reqs:
         dep = rq.split(" ")[0].strip()
@@ -572,6 +562,28 @@ def run_conda_forge_specific(
                 "The feedstock has no `.ci_support` files and thus will not build any packages."
             )
 
+    # 8: Ensure the recipe specifies a Python build backend if needed
+    host_or_build_reqs = (requirements_section.get("host") or []) or (
+        requirements_section.get("build") or []
+    )
+    hint_pip_no_build_backend(host_or_build_reqs, recipe_name, hints)
+    for out in outputs_section:
+        if recipe_version == 1:
+            output_requirements = rattler_loader.load_all_requirements(out)
+            build_reqs = output_requirements.get("build") or []
+            host_reqs = output_requirements.get("host") or []
+        else:
+            _req = out.get("requirements") or {}
+            if isinstance(_req, Mapping):
+                build_reqs = _req.get("build") or []
+                host_reqs = _req.get("host") or []
+            else:
+                build_reqs = []
+                host_reqs = []
+
+        name = out.get("name", "").strip()
+        hint_pip_no_build_backend(host_reqs or build_reqs, name, hints)
+
     # 9: No duplicates in conda-forge.yml
     if (
         not is_staged_recipes

conda_smithy/linter/hints.py

@@ -7,7 +7,11 @@
 
 from conda_smithy.linter import conda_recipe_v1_linter
 from conda_smithy.linter.errors import HINT_NO_ARCH
-from conda_smithy.linter.utils import find_local_config_file, is_selector_line
+from conda_smithy.linter.utils import (
+    VALID_PYTHON_BUILD_BACKENDS,
+    find_local_config_file,
+    is_selector_line,
+)
 from conda_smithy.utils import get_yaml
 
 
@@ -174,3 +178,30 @@ def hint_check_spdx(about_section, hints):
             "Documentation on acceptable licenses can be found "
             "[here]( https://conda-forge.org/docs/maintainer/adding_pkgs.html#spdx-identifiers-and-expressions )."
         )
+
+
+def hint_pip_no_build_backend(host_or_build_section, package_name, hints):
+    if host_or_build_section and any(
+        req.split(" ")[0] == "pip" for req in host_or_build_section
+    ):
+        found_backend = False
+        for backend in VALID_PYTHON_BUILD_BACKENDS:
+            if any(
+                req.split(" ")[0]
+                in [
+                    backend,
+                    backend.replace("-", "_"),
+                    backend.replace("_", "-"),
+                ]
+                for req in host_or_build_section
+            ):
+                found_backend = True
+                break
+
+        if not found_backend:
+            hints.append(
+                f"No valid build backend found for Python recipe for package `{package_name}` using `pip`. Python recipes using `pip` need to "
+                "explicitly specify a build backend in the `host` section. "
+                "If your recipe has built with only `pip` in the `host` section in the past, you likely should "
+                "add `setuptools` to the `host` section of your recipe."
+            )

conda_smithy/linter/utils.py

@@ -1,17 +1,25 @@
 import copy
 import os
 import re
+import sys
 from collections.abc import Sequence
+from functools import lru_cache
 from glob import glob
 from typing import Dict, List, Mapping, Optional, Union
 
+import requests
 from conda.models.version import InvalidVersionSpec, VersionOrder
 from conda_build.metadata import (
     FIELDS as _CONDA_BUILD_FIELDS,
 )
 from rattler_build_conda_compat import loader as rattler_loader
 from rattler_build_conda_compat.recipe_sources import get_all_sources
 
+if sys.version_info[:2] < (3, 11):
+    import tomli as tomllib
+else:
+    import tomllib
+
 FIELDS = copy.deepcopy(_CONDA_BUILD_FIELDS)
 
 # Just in case 'extra' moves into conda_build
@@ -46,6 +54,19 @@
 CONDA_BUILD_TOOL = "conda-build"
 RATTLER_BUILD_TOOL = "rattler-build"
 
+VALID_PYTHON_BUILD_BACKENDS = [
+    "setuptools",
+    "flit-core",
+    "hatchling",
+    "poetry-core",
+    "pdm-backend",
+    "pdm-pep517",
+    "meson-python",
+    "scikit-build-core",
+    "maturin",
+    "jupyter_packaging",
+]
+
 
 def get_section(parent, name, lints, recipe_version: int = 0):
     if recipe_version == 0:
@@ -185,3 +206,15 @@ def _lint_package_version(version: Optional[str]) -> Optional[str]:
         VersionOrder(ver)
     except InvalidVersionSpec as e:
         return invalid_version.format(ver=ver, err=e)
+
+
+@lru_cache(maxsize=1)
+def load_linter_toml_metdata():
+    hints_toml_url = "https://raw.githubusercontent.com/conda-forge/conda-forge-pinning-feedstock/main/recipe/linter_hints/hints.toml"
+    hints_toml_req = requests.get(hints_toml_url)
+    if hints_toml_req.status_code != 200:
+        # too bad, but not important enough to throw an error;
+        # linter will rerun on the next commit anyway
+        return None
+    hints_toml_str = hints_toml_req.content.decode("utf-8")
+    return tomllib.loads(hints_toml_str)

news/2039-pip-backend-hint.rst

@@ -0,0 +1,23 @@
+**Added:**
+
+* Added hint for missing ``pip`` build backend in the ``host`` section of the recipe. (#2039)
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>