More robust handling of type guard imports (#208)

Author: gaborbernat

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## 1.15.2
+
+- Log a warning instead of crashing when a type guard import fails to resolve
+- When resolving type guard imports if the target module does not have source code (such is the case for C-extension modules) do nothing instead of crashing
+
 ## 1.15.1
 
 - Fix `fully_qualified` should be `typehints_fully_qualified`

src/sphinx_autodoc_typehints/__init__.py

@@ -271,7 +271,7 @@ def get_all_type_hints(obj: Any, name: str) -> dict[str, Any]:
     return _get_type_hint(name, obj)
 
 
-_TYPE_GUARD_IMPORT_RE = re.compile(r"if (typing.)?TYPE_CHECKING:([\s\S]*?)(?=\n\S)")
+_TYPE_GUARD_IMPORT_RE = re.compile(r"if (typing.)?TYPE_CHECKING:[^\n]*([\s\S]*?)(?=\n\S)")
 _TYPE_GUARD_IMPORTS_RESOLVED = set()
 
 
@@ -281,10 +281,17 @@ def _resolve_type_guarded_imports(obj: Any) -> None:
         if obj.__module__ not in sys.builtin_module_names:
             module = inspect.getmodule(obj)
             if module:
-                module_code = inspect.getsource(module)
-                for (_, part) in _TYPE_GUARD_IMPORT_RE.findall(module_code):
-                    module_code = textwrap.dedent(part)
-                    exec(module_code, obj.__globals__)
+                try:
+                    module_code = inspect.getsource(module)
+                except OSError:
+                    ...  # no source code => no type guards
+                else:
+                    for (_, part) in _TYPE_GUARD_IMPORT_RE.findall(module_code):
+                        guarded_code = textwrap.dedent(part)
+                        try:
+                            exec(guarded_code, obj.__globals__)
+                        except Exception as exc:
+                            _LOGGER.warning(f"Failed guarded type import with {exc!r}")
 
 
 def _get_type_hint(name: str, obj: Any) -> dict[str, Any]:

tests/roots/test-resolve-typing-guard/demo_typing_guard.py

@@ -14,6 +14,10 @@
     from typing import AnyStr
 
 
+if TYPE_CHECKING:  # bad import
+    from functools import missing  # noqa: F401
+
+
 def a(f: Decimal, s: AnyStr) -> Sequence[AnyStr | Decimal]:
     """
     Do.

tests/test_sphinx_autodoc_typehints.py

@@ -35,6 +35,7 @@
 from sphobjinv import Inventory
 
 from sphinx_autodoc_typehints import (
+    _resolve_type_guarded_imports,
     backfill_type_hints,
     format_annotation,
     get_annotation_args,
@@ -822,4 +823,12 @@ def test_resolve_typing_guard_imports(app: SphinxTestApp, status: StringIO, warn
     set_python_path()
     app.build()
     assert "build succeeded" in status.getvalue()
-    assert not warning.getvalue()
+    pat = r'WARNING: Failed guarded type import with ImportError\("cannot import name \'missing\' from \'functools\''
+    err = warning.getvalue()
+    assert re.search(pat, err)
+
+
+def test_no_source_code_type_guard() -> None:
+    from csv import Error
+
+    _resolve_type_guarded_imports(Error)

whitelist.txt

@@ -5,6 +5,7 @@ backfill
 conf
 contravariant
 cpython
+csv
 dedent
 dirname
 docnames