Update submodule_path after finding an editable install

astroid/interpreter/_import/spec.py

@@ -64,6 +64,11 @@ class ModuleType(enum.Enum):
     "_SixMetaPathImporter": ModuleType.PY_SOURCE,
 }
 
+_EditableFinderClasses: set[str] = {
+    "_EditableFinder",
+    "_EditableNamespaceFinder",
+}
+
 
 class ModuleSpec(NamedTuple):
     """Defines a class similar to PEP 420's ModuleSpec.
@@ -453,8 +458,13 @@ def find_spec(modpath: list[str], path: Sequence[str] | None = None) -> ModuleSp
             _path, modname, module_parts, processed, submodule_path or path
         )
         processed.append(modname)
-        if modpath and isinstance(finder, Finder):
-            submodule_path = finder.contribute_to_path(spec, processed)
+        if modpath:
+            if isinstance(finder, Finder):
+                submodule_path = finder.contribute_to_path(spec, processed)
+            # If modname is a package from an editable install, update submodule_path
+            # so that the next module in the path will be found inside of it using importlib.
+            elif finder.__name__ in _EditableFinderClasses:
+                submodule_path = spec.submodule_search_locations
 
         if spec.type == ModuleType.PKG_DIRECTORY:
             spec = spec._replace(submodule_search_locations=submodule_path)

tests/test_modutils.py

@@ -550,3 +550,15 @@ def test_is_module_name_part_of_extension_package_whitelist_success(self) -> Non
 @pytest.mark.skipif(not HAS_URLLIB3, reason="This test requires urllib3.")
 def test_file_info_from_modpath__SixMetaPathImporter() -> None:
     assert modutils.file_info_from_modpath(["urllib3.packages.six.moves.http_client"])
+
+
+def test_find_setuptools_pep660_editable_install():
+    """Find the spec for a package installed via setuptools PEP 660 import hooks."""
+    # pylint: disable-next=import-outside-toplevel
+    from tests.testdata.python3.data.import_setuptools_pep660.__editable___example_0_1_0_finder import (
+        _EditableFinder,
+    )
+
+    with unittest.mock.patch.object(sys, "meta_path", new=[_EditableFinder]):
+        assert spec.find_spec(["example"])
+        assert spec.find_spec(["example", "subpackage"])

tests/testdata/python3/data/import_setuptools_pep660/__editable___example_0_1_0_finder.py

@@ -0,0 +1,72 @@
+"""This file contains Finders automatically generated by setuptools for a package installed
+in editable mode via custom import hooks. It's generated here:
+https://github.com/pypa/setuptools/blob/c34b82735c1a9c8707bea00705ae2f621bf4c24d/setuptools/command/editable_wheel.py#L732-L801
+"""
+import sys
+from importlib.machinery import ModuleSpec
+from importlib.machinery import all_suffixes as module_suffixes
+from importlib.util import spec_from_file_location
+from itertools import chain
+from pathlib import Path
+
+MAPPING = {"example": Path(__file__).parent.resolve() / "example"}
+NAMESPACES = {}
+PATH_PLACEHOLDER = "__editable__.example-0.1.0.finder" + ".__path_hook__"
+
+
+class _EditableFinder:  # MetaPathFinder
+    @classmethod
+    def find_spec(cls, fullname, path=None, target=None):
+        for pkg, pkg_path in reversed(list(MAPPING.items())):
+            if fullname == pkg or fullname.startswith(f"{pkg}."):
+                rest = fullname.replace(pkg, "", 1).strip(".").split(".")
+                return cls._find_spec(fullname, Path(pkg_path, *rest))
+
+        return None
+
+    @classmethod
+    def _find_spec(cls, fullname, candidate_path):
+        init = candidate_path / "__init__.py"
+        candidates = (candidate_path.with_suffix(x) for x in module_suffixes())
+        for candidate in chain([init], candidates):
+            if candidate.exists():
+                return spec_from_file_location(fullname, candidate)
+
+
+class _EditableNamespaceFinder:  # PathEntryFinder
+    @classmethod
+    def _path_hook(cls, path):
+        if path == PATH_PLACEHOLDER:
+            return cls
+        raise ImportError
+
+    @classmethod
+    def _paths(cls, fullname):
+        # Ensure __path__ is not empty for the spec to be considered a namespace.
+        return NAMESPACES[fullname] or MAPPING.get(fullname) or [PATH_PLACEHOLDER]
+
+    @classmethod
+    def find_spec(cls, fullname, target=None):
+        if fullname in NAMESPACES:
+            spec = ModuleSpec(fullname, None, is_package=True)
+            spec.submodule_search_locations = cls._paths(fullname)
+            return spec
+        return None
+
+    @classmethod
+    def find_module(cls, fullname):
+        return None
+
+
+def install():
+    if not any(finder == _EditableFinder for finder in sys.meta_path):
+        sys.meta_path.append(_EditableFinder)
+
+    if not NAMESPACES:
+        return
+
+    if not any(hook == _EditableNamespaceFinder._path_hook for hook in sys.path_hooks):
+        # PathEntryFinder is needed to create NamespaceSpec without private APIS
+        sys.path_hooks.append(_EditableNamespaceFinder._path_hook)
+    if PATH_PLACEHOLDER not in sys.path:
+        sys.path.append(PATH_PLACEHOLDER)  # Used just to trigger the path hook

tests/testdata/python3/data/import_setuptools_pep660/example/__init__.py

@@ -0,0 +1 @@
+from subpackage import hello

tests/testdata/python3/data/import_setuptools_pep660/example/subpackage/__init__.py

@@ -0,0 +1 @@
+hello = 1