From cdc41f1731e7ebe6df96e90b5004bc0093c2cc14 Mon Sep 17 00:00:00 2001
From: Guido van Rossum <guido@python.org>
Date: Fri, 25 Aug 2023 17:04:35 -0700
Subject: [PATCH 1/3] Remove assert that should've been DEOPT_IF

The assert(method != NULL) in CALL_NO_KW_LIST_APPEND is wrong --
this condition should lead to a deoptimization, and indeed there
is a DEOPT_IF two lines later that will trigger if method == NULL.

This would crash in a devious repro scenario (first seen live
in boto3 tests) when compiled with assertions enabled.
In a production version there is no crash, so impact is limited.

(The crash also appears in main; I will prepare a separate PR.)
---
 Python/bytecodes.c         | 2 +-
 Python/generated_cases.c.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index dc2ae221f0bdb1..d1c79371c4525a 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -2992,7 +2992,7 @@ dummy_func(
         inst(CALL_NO_KW_LIST_APPEND, (unused/1, unused/2, method, self, args[oparg] -- unused)) {
             assert(kwnames == NULL);
             assert(oparg == 1);
-            assert(method != NULL);
+
             PyInterpreterState *interp = _PyInterpreterState_GET();
             DEOPT_IF(method != interp->callable_cache.list_append, CALL);
             DEOPT_IF(!PyList_Check(self), CALL);
diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
index b0a363ce9aa111..e697352b8d9d08 100644
--- a/Python/generated_cases.c.h
+++ b/Python/generated_cases.c.h
@@ -4248,7 +4248,7 @@
             #line 2993 "Python/bytecodes.c"
             assert(kwnames == NULL);
             assert(oparg == 1);
-            assert(method != NULL);
+
             PyInterpreterState *interp = _PyInterpreterState_GET();
             DEOPT_IF(method != interp->callable_cache.list_append, CALL);
             DEOPT_IF(!PyList_Check(self), CALL);

From 298cf2ff2f56f346f8fbaf4da3f09ae0d36ceb1a Mon Sep 17 00:00:00 2001
From: Guido van Rossum <guido@python.org>
Date: Fri, 25 Aug 2023 21:26:58 -0700
Subject: [PATCH 2/3] Add back a different assert(self != NULL)

---
 Python/bytecodes.c         | 2 +-
 Python/generated_cases.c.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index d1c79371c4525a..5e80e06205ae4e 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -2992,9 +2992,9 @@ dummy_func(
         inst(CALL_NO_KW_LIST_APPEND, (unused/1, unused/2, method, self, args[oparg] -- unused)) {
             assert(kwnames == NULL);
             assert(oparg == 1);
-
             PyInterpreterState *interp = _PyInterpreterState_GET();
             DEOPT_IF(method != interp->callable_cache.list_append, CALL);
+            assert(self != NULL);
             DEOPT_IF(!PyList_Check(self), CALL);
             STAT_INC(CALL, hit);
             if (_PyList_AppendTakeRef((PyListObject *)self, args[0]) < 0) {
diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
index e697352b8d9d08..a3c049569268c1 100644
--- a/Python/generated_cases.c.h
+++ b/Python/generated_cases.c.h
@@ -4248,9 +4248,9 @@
             #line 2993 "Python/bytecodes.c"
             assert(kwnames == NULL);
             assert(oparg == 1);
-
             PyInterpreterState *interp = _PyInterpreterState_GET();
             DEOPT_IF(method != interp->callable_cache.list_append, CALL);
+            assert(self != NULL);
             DEOPT_IF(!PyList_Check(self), CALL);
             STAT_INC(CALL, hit);
             if (_PyList_AppendTakeRef((PyListObject *)self, args[0]) < 0) {

From d39847d8b6585745e6af12b4ace1b292342bfee0 Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Sat, 26 Aug 2023 04:33:21 +0000
Subject: [PATCH 3/3] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20blu?=
 =?UTF-8?q?rb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../2023-08-26-04-33-18.gh-issue-108487.aUFxqf.rst               | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2023-08-26-04-33-18.gh-issue-108487.aUFxqf.rst

diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-08-26-04-33-18.gh-issue-108487.aUFxqf.rst b/Misc/NEWS.d/next/Core and Builtins/2023-08-26-04-33-18.gh-issue-108487.aUFxqf.rst
new file mode 100644
index 00000000000000..1117bcd7e9852b
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2023-08-26-04-33-18.gh-issue-108487.aUFxqf.rst	
@@ -0,0 +1 @@
+Change an assert that would cause a spurious crash in a devious case that should only trigger deoptimization.