gh-60115: Support frozen modules for linecache.getline()

Lib/linecache.py

@@ -63,6 +63,16 @@ def _getlines_from_code(code):
     return []
 
 
+def _source_unavailable(filename):
+    """Return True if the source code is unavailable for such file name."""
+    return (
+        not filename
+        or (filename.startswith('<')
+            and filename.endswith('>')
+            and not filename.startswith('<frozen '))
+    )
+
+
 def checkcache(filename=None):
     """Discard cache entries that are out of date.
     (This is not checked upon each call!)"""
@@ -118,10 +128,17 @@ def updatecache(filename, module_globals=None):
     if filename in cache:
         if len(cache[filename]) != 1:
             cache.pop(filename, None)
-    if not filename or (filename.startswith('<') and filename.endswith('>')):
+    if _source_unavailable(filename):
         return []
 
-    fullname = filename
+    if filename.startswith('<frozen ') and module_globals is not None:
+        # This is a frozen module, so we need to use the filename
+        # from the module globals.
+        fullname = module_globals.get('__file__')
+        if fullname is None:
+            return []
+    else:
+        fullname = filename
     try:
         stat = os.stat(fullname)
     except OSError:

Lib/test/test_linecache.py

@@ -281,6 +281,19 @@ def test_loader(self):
         self.assertEqual(linecache.getlines(filename, module_globals),
                          ['source for x.y.z\n'])
 
+    def test_frozen(self):
+        filename = '<frozen fakemodule>'
+        module_globals = {'__file__': FILENAME}
+        empty = linecache.getlines(filename)
+        self.assertEqual(empty, [])
+        lines = linecache.getlines(filename, module_globals)
+        self.assertGreater(len(lines), 0)
+        lines_cached = linecache.getlines(filename)
+        self.assertEqual(lines, lines_cached)
+        linecache.clearcache()
+        empty = linecache.getlines(filename)
+        self.assertEqual(empty, [])
+
     def test_invalid_names(self):
         for name, desc in [
             ('\x00', 'NUL bytes filename'),

Misc/NEWS.d/next/Library/2025-03-23-18-39-07.gh-issue-60115.AWdcmq.rst

@@ -0,0 +1 @@
+Support frozen modules for :func:`linecache.getline`.