From 4fc82b6d3b99f873179937215833e7a573ca7876 Mon Sep 17 00:00:00 2001
From: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>
Date: Fri, 7 Jun 2024 22:37:35 +0100
Subject: gh-120225: fix crash in compiler on empty block at end of exception
 handler (#120235)

---
 Lib/test/test_compile.py                                       | 10 ++++++++++
 .../2024-06-07-16-09-04.gh-issue-120225.kuYf9t.rst             |  1 +
 Python/flowgraph.c                                             |  8 ++------
 3 files changed, 13 insertions(+), 6 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2024-06-07-16-09-04.gh-issue-120225.kuYf9t.rst

diff --git a/Lib/test/test_compile.py b/Lib/test/test_compile.py
index ba0bcc9..ae23aea 100644
--- 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
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 17617e1..aed694a 100644
--- 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 */
-- 
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