[3.11] pythongh-107901: Fix missing line number on BACKWARD_JUMP at t…

…he end of a for loop

Lib/test/test_compile.py

@@ -990,6 +990,20 @@ async def test(aseq):
         code_lines = self.get_code_lines(test.__code__)
         self.assertEqual(expected_lines, code_lines)
 
+    def test_lineno_of_backward_jump(self):
+        # Issue gh-107901
+        def f():
+            for i in x:
+                if y:
+                    pass
+
+        linenos = list(inst.positions.lineno
+                       for inst in dis.get_instructions(f.__code__)
+                       if inst.opname == 'JUMP_BACKWARD')
+
+        self.assertTrue(len(linenos) > 0)
+        self.assertTrue(all(l is not None for l in linenos))
+
     def test_big_dict_literal(self):
         # The compiler has a flushing point in "compiler_dict" that calls compiles
         # a portion of the dictionary literal when the loop that iterates over the items

Misc/NEWS.d/next/Core and Builtins/2023-08-22-18-38-45.bpo-107901.XgXVgU.rst

@@ -0,0 +1 @@
+Fix missing line number on :opcode:`JUMP_BACKWARD` at the end of a for loop.

Python/compile.c

@@ -3123,7 +3123,7 @@ compiler_for(struct compiler *c, stmt_ty s)
     VISIT(c, expr, s->v.For.target);
     VISIT_SEQ(c, stmt, s->v.For.body);
     /* Mark jump as artificial */
-    UNSET_LOC(c);
+    SET_LOC(c, s->v.For.iter);
     ADDOP_JUMP(c, JUMP, start);
     compiler_use_next_block(c, cleanup);