gh-117500: Add a new route in linecache to fetch interactive source code

Signed-off-by: Pablo Galindo <pablogsal@gmail.com>

Author: pablogsal

Lib/inspect.py

@@ -968,6 +968,8 @@ def findsource(object):
     module = getmodule(object, file)
     if module:
         lines = linecache.getlines(file, module.__dict__)
+        if not lines and file.startswith('<') and hasattr(object, "__code__"):
+            lines = linecache._getlines_from_code(object.__code__, module.__dict__)
     else:
         lines = linecache.getlines(file)
     if not lines:

Lib/linecache.py

@@ -11,6 +11,7 @@
 # The cache. Maps filenames to either a thunk which will provide source code,
 # or a tuple (size, mtime, lines, fullname) once loaded.
 cache = {}
+_interactive_cache = {}
 
 
 def clearcache():
@@ -44,6 +45,21 @@ def getlines(filename, module_globals=None):
         return []
 
 
+def _getline_from_code(filename, lineno, module_globals=None):
+    lines = _getlines_from_code(filename, module_globals)
+    if 1 <= lineno <= len(lines):
+        return lines[lineno - 1]
+    return ''
+
+
+def _getlines_from_code(code, module_globals=None):
+    if code in _interactive_cache:
+        entry = _interactive_cache[code]
+        if len(entry) != 1:
+            return _interactive_cache[code][2]
+    return []
+
+
 def checkcache(filename=None):
     """Discard cache entries that are out of date.
     (This is not checked upon each call!)"""
@@ -196,8 +212,14 @@ def get_lines(name=name, *args, **kwargs):
 
 
 def _register_code(code, string, name):
-    cache[code] = (
-            len(string),
-            None,
-            [line + '\n' for line in string.splitlines()],
-            name)
+    entry = (len(string),
+             None,
+             [line + '\n' for line in string.splitlines()],
+             name)
+    stack = [code]
+    while stack:
+        code = stack.pop()
+        for const in code.co_consts:
+            if isinstance(const, type(code)):
+                stack.append(const)
+        _interactive_cache[code] = entry

Lib/test/test_io.py

@@ -4558,11 +4558,11 @@ def test_check_encoding_warning(self):
         ''')
         proc = assert_python_ok('-X', 'warn_default_encoding', '-c', code)
         warnings = proc.err.splitlines()
-        self.assertEqual(len(warnings), 4)
+        self.assertEqual(len(warnings), 2)
         self.assertTrue(
             warnings[0].startswith(b"<string>:5: EncodingWarning: "))
         self.assertTrue(
-            warnings[2].startswith(b"<string>:8: EncodingWarning: "))
+            warnings[1].startswith(b"<string>:8: EncodingWarning: "))
 
     def test_text_encoding(self):
         # PEP 597, bpo-47000. io.text_encoding() returns "locale" or "utf-8"

Lib/traceback.py

@@ -288,11 +288,11 @@ class FrameSummary:
     """
 
     __slots__ = ('filename', 'lineno', 'end_lineno', 'colno', 'end_colno',
-                 'name', '_lines', '_lines_dedented', 'locals')
+                 'name', '_lines', '_lines_dedented', 'locals', '_frame')
 
     def __init__(self, filename, lineno, name, *, lookup_line=True,
             locals=None, line=None,
-            end_lineno=None, colno=None, end_colno=None):
+            end_lineno=None, colno=None, end_colno=None, **kwargs):
         """Construct a FrameSummary.
 
         :param lookup_line: If True, `linecache` is consulted for the source
@@ -308,6 +308,7 @@ def __init__(self, filename, lineno, name, *, lookup_line=True,
         self.colno = colno
         self.end_colno = end_colno
         self.name = name
+        self._frame = kwargs.get("_frame")
         self._lines = line
         self._lines_dedented = None
         if lookup_line:
@@ -347,7 +348,12 @@ def _set_lines(self):
             lines = []
             for lineno in range(self.lineno, self.end_lineno + 1):
                 # treat errors (empty string) and empty lines (newline) as the same
-                lines.append(linecache.getline(self.filename, lineno).rstrip())
+                line = None
+                if self._frame is not None and self.filename.startswith("<"):
+                    line = linecache._getline_from_code(self._frame.f_code, lineno, self._frame.f_globals).rstrip()
+                if line is None:
+                    line = linecache.getline(self.filename, lineno).rstrip()
+                lines.append(line)
             self._lines = "\n".join(lines) + "\n"
 
     @property
@@ -480,9 +486,13 @@ def _extract_from_extended_frame_gen(klass, frame_gen, *, limit=None,
                 f_locals = f.f_locals
             else:
                 f_locals = None
-            result.append(FrameSummary(
-                filename, lineno, name, lookup_line=False, locals=f_locals,
-                end_lineno=end_lineno, colno=colno, end_colno=end_colno))
+            result.append(
+                FrameSummary(filename, lineno, name,
+                    lookup_line=False, locals=f_locals,
+                    end_lineno=end_lineno, colno=colno, end_colno=end_colno,
+                    _frame=f,
+                )
+            )
         for filename in fnames:
             linecache.checkcache(filename)
 

Python/pythonrun.c

@@ -1383,7 +1383,7 @@ run_mod(mod_ty mod, PyObject *filename, PyObject *globals, PyObject *locals,
 
         PyObject* result = PyObject_CallFunction(
             print_tb_func, "OOO",
-            interactive_filename,
+            co,
             interactive_src,
             filename
         );