fix: Don't consider imported objects as public

Discussion-169: mkdocstrings/python#169

src/griffe/mixins.py

@@ -367,8 +367,8 @@ def is_public(self) -> bool:
         # TODO: Return regular True/False values in next version.
         if self.public is not None:  # type: ignore[attr-defined]
             return _True if self.public else _False  # type: ignore[return-value,attr-defined]
-        if self.is_wildcard_exposed:
-            return _True  # type: ignore[return-value]
+        if self.parent and self.parent.is_module and bool(self.parent.exports):  # type: ignore[attr-defined]
+            return _True if self.name in self.parent.exports else _False  # type: ignore[attr-defined,return-value]
         if self.has_private_name:
             return _False  # type: ignore[return-value]
         # The following condition effectively filters out imported objects.
@@ -389,6 +389,9 @@ def __init__(self, value: bool) -> None:  # noqa: FBT001
     def __bool__(self) -> bool:
         return self.value
 
+    def __repr__(self) -> str:
+        return repr(self.value)
+
     def __call__(self, *args: Any, **kwargs: Any) -> bool:  # noqa: ARG002
         warnings.warn(
             "This method is now a property and should be accessed as such (without parentheses).",

tests/test_diff.py

@@ -181,7 +181,7 @@ def test_diff_griffe(old_code: str, new_code: str, expected_breakages: list[Brea
     for breakage, expected_kind in zip(breaking, expected_breakages):
         assert breakage.kind is expected_kind
     # check with aliases
-    import_a = "from ._mod_a import a"
+    import_a = "from ._mod_a import a\n__all__ = ['a']"
     old_modules = {"__init__.py": import_a, "_mod_a.py": old_code}
     new_modules = {"__init__.py": new_code and import_a, "_mod_a.py": new_code}
     with temporary_visited_package("package_old", old_modules) as old_package:  # noqa: SIM117

tests/test_public_api.py

@@ -0,0 +1,10 @@
+"""Tests for public API handling."""
+
+from griffe.tests import temporary_visited_module
+
+
+def test_not_detecting_imported_objects_as_public() -> None:
+    """Imported objects not listed in `__all__` must not be considered public."""
+    with temporary_visited_module("from abc import ABC\ndef func(): ...") as module:
+        assert not module["ABC"].is_public
+        assert module["func"].is_public  # control case