gh-120225: fix crash in compiler on empty block at end of exception handler (#120235)

diff --git a/Lib/test/test_compile.py b/Lib/test/test_compile.py
index ba0bcc9c1ced99838c1c1d89db99f2569f6a1fad..ae23aea08d99bc0a10219cfc7b7f7bdc9dbaa339 100644 (file)
--- a/Lib/test/test_compile.py
+++ b/Lib/test/test_compile.py
@@ -1409,6 +1409,16 @@ class TestSpecifics(unittest.TestCase):
         for kw in ("except", "except*"):
             exec(code % kw, g, l);
 
+    def test_regression_gh_120225(self):
+        async def name_4():
+            match b'':
+                case True:
+                    pass
+                case name_5 if f'e':
+                    {name_3: name_4 async for name_2 in name_5}
+                case []:
+                    pass
+            [[]]
 
 @requires_debug_ranges()
 class TestSourcePositions(unittest.TestCase):

diff --git a/Misc/NEWS.d/next/Core and Builtins/2024-06-07-16-09-04.gh-issue-120225.kuYf9t.rst b/Misc/NEWS.d/next/Core and Builtins/2024-06-07-16-09-04.gh-issue-120225.kuYf9t.rst
new file mode 100644 (file)
index 0000000..d00b9aa
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2024-06-07-16-09-04.gh-issue-120225.kuYf9t.rst
@@ -0,0 +1 @@
+Fix crash in compiler on empty block at end of exception handler.

diff --git a/Python/flowgraph.c b/Python/flowgraph.c
index 17617e119fdaa4458a91b38938a6ee1433e3a420..aed694aee91f9165494444ed9ba561698b6e69a4 100644 (file)
--- a/Python/flowgraph.c
+++ b/Python/flowgraph.c
@@ -2304,15 +2304,11 @@ push_cold_blocks_to_end(cfg_builder *g) {
             if (!IS_LABEL(b->b_next->b_label)) {
                 b->b_next->b_label.id = next_lbl++;
             }
-            cfg_instr *prev_instr = basicblock_last_instr(b);
-            // b cannot be empty because at the end of an exception handler
-            // there is always a POP_EXCEPT + RERAISE/RETURN
-            assert(prev_instr);
-
             basicblock_addop(explicit_jump, JUMP_NO_INTERRUPT, b->b_next->b_label.id,
-                             prev_instr->i_loc);
+                             NO_LOCATION);
             explicit_jump->b_cold = 1;
             explicit_jump->b_next = b->b_next;
+            explicit_jump->b_predecessors = 1;
             b->b_next = explicit_jump;
 
             /* set target */