Fix issue in inferred caller when resourcse package has no source.

importlib_resources/_common.py

@@ -87,13 +87,19 @@ def _(cand: None) -> types.ModuleType:
     return resolve(_infer_caller().f_globals['__name__'])
 
 
+@functools.lru_cache
+def _this_filename():
+    frame = inspect.currentframe()
+    return __file__ if frame is None else inspect.getframeinfo(frame).filename
+
+
 def _infer_caller():
     """
     Walk the stack and find the frame of the first caller not in this module.
     """
 
     def is_this_file(frame_info):
-        return frame_info.filename == __file__
+        return frame_info.filename == _this_filename()
 
     def is_wrapper(frame_info):
         return frame_info.function == 'wrapper'

importlib_resources/tests/test_files.py

@@ -1,3 +1,7 @@
+import os
+import pathlib
+import py_compile
+import shutil
 import textwrap
 import unittest
 import warnings
@@ -7,6 +11,7 @@
 import importlib_resources as resources
 from ..abc import Traversable
 from . import util
+from .compat.py39 import os_helper, import_helper
 
 
 @contextlib.contextmanager
@@ -108,6 +113,10 @@ class ImplicitContextFiles:
             'submod.py': set_val,
             'res.txt': 'resources are the best',
         },
+        'frozenpkg': {
+            '__init__.py': set_val.replace('importlib_resources', 'c_resources'),
+            'res.txt': 'resources are the best',
+        },
     }
 
     def test_implicit_files_package(self):
@@ -122,6 +131,27 @@ def test_implicit_files_submodule(self):
         """
         assert importlib.import_module('somepkg.submod').val == 'resources are the best'
 
+    def _compile_importlib(self):
+        """
+        Make a compiled-only copy of the importlib resources package.
+        """
+        bin_site = self.fixtures.enter_context(os_helper.temp_dir())
+        c_resources = pathlib.Path(bin_site, 'c_resources')
+        sources = pathlib.Path(resources.__file__).parent
+        shutil.copytree(sources, c_resources, ignore=lambda *_: ['__pycache__'])
+
+        for dirpath, _, filenames in os.walk(c_resources):
+            for filename in filenames:
+                source_path = pathlib.Path(dirpath) / filename
+                cfile = source_path.with_suffix('.pyc')
+                py_compile.compile(source_path, cfile)
+                pathlib.Path.unlink(source_path)
+        self.fixtures.enter_context(import_helper.DirsOnSysPath(bin_site))
+
+    def test_implicit_files_with_compiled_importlib(self):
+        self._compile_importlib()
+        assert importlib.import_module('frozenpkg').val == 'resources are the best'
+
 
 class ImplicitContextFilesDiskTests(
     DirectSpec, util.DiskSetup, ImplicitContextFiles, unittest.TestCase