From de44492d7d6d9235d240259cd2091c03ac5122d1 Mon Sep 17 00:00:00 2001
From: Irit Katriel <iritkatriel@yahoo.com>
Date: Sat, 27 Apr 2024 17:18:39 +0100
Subject: [PATCH 1/7] gh-116767: fix crash on 'async with' with many context
 managers

---
 Lib/test/test_syntax.py | 25 +++++++++++++++++++++++++
 Python/compile.c        | 15 ++++++++++++++-
 Python/flowgraph.c      |  2 +-
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index e9bec3317811dd..491cd8bb7daa42 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -2402,6 +2402,31 @@ def bug():
             with self.subTest(f"out of range: {n=}"):
                 self._check_error(get_code(n), "too many statically nested blocks")
 
+    @support.cpython_only
+    def test_async_with_statement_many_context_managers(self):
+        # See gh-116767
+
+        def get_code(n):
+            code = [ textwrap.dedent("""
+                async def bug():
+                    async with (
+                    a
+                """) ]
+            for i in range(n):
+                code.append(f"    as a{i}, a\n")
+            code.append("): yield a")
+            return "".join(code)
+
+        CO_MAXBLOCKS = 20  # static nesting limit of the compiler
+
+        for n in range(CO_MAXBLOCKS):
+            with self.subTest(f"within range: {n=}"):
+                compile(get_code(n), "<string>", "exec")
+
+        for n in range(CO_MAXBLOCKS, CO_MAXBLOCKS + 5):
+            with self.subTest(f"out of range: {n=}"):
+                self._check_error(get_code(n), "too many statically nested blocks")
+
     def test_barry_as_flufl_with_syntax_errors(self):
         # The "barry_as_flufl" rule can produce some "bugs-at-a-distance" if
         # is reading the wrong token in the presence of syntax errors later
diff --git a/Python/compile.c b/Python/compile.c
index ca5551a8e64ab0..370c773cad70a6 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -113,7 +113,8 @@ compiler IR.
 
 enum fblocktype { WHILE_LOOP, FOR_LOOP, TRY_EXCEPT, FINALLY_TRY, FINALLY_END,
                   WITH, ASYNC_WITH, HANDLER_CLEANUP, POP_VALUE, EXCEPTION_HANDLER,
-                  EXCEPTION_GROUP_HANDLER, ASYNC_COMPREHENSION_GENERATOR };
+                  EXCEPTION_GROUP_HANDLER, ASYNC_COMPREHENSION_GENERATOR,
+                  STOP_ITERATION };
 
 struct fblockinfo {
     enum fblocktype fb_type;
@@ -1503,6 +1504,7 @@ compiler_unwind_fblock(struct compiler *c, location *ploc,
         case EXCEPTION_HANDLER:
         case EXCEPTION_GROUP_HANDLER:
         case ASYNC_COMPREHENSION_GENERATOR:
+        case STOP_ITERATION:
             return SUCCESS;
 
         case FOR_LOOP:
@@ -2232,6 +2234,16 @@ compiler_function_body(struct compiler *c, stmt_ty s, int is_async, Py_ssize_t f
     c->u->u_metadata.u_argcount = asdl_seq_LEN(args->args);
     c->u->u_metadata.u_posonlyargcount = asdl_seq_LEN(args->posonlyargs);
     c->u->u_metadata.u_kwonlyargcount = asdl_seq_LEN(args->kwonlyargs);
+
+    NEW_JUMP_TARGET_LABEL(c, start);
+    USE_LABEL(c, start);
+    if (c->u->u_ste->ste_coroutine || c->u->u_ste->ste_generator) {
+        /* wrap_in_stopiteration_handler will push a block, so we need to account for that */
+        RETURN_IF_ERROR(
+            compiler_push_fblock(c, NO_LOCATION, STOP_ITERATION,
+                                 start, NO_LABEL, NULL));
+    }
+
     for (Py_ssize_t i = first_instr; i < asdl_seq_LEN(body); i++) {
         VISIT_IN_SCOPE(c, stmt, (stmt_ty)asdl_seq_GET(body, i));
     }
@@ -2240,6 +2252,7 @@ compiler_function_body(struct compiler *c, stmt_ty s, int is_async, Py_ssize_t f
             compiler_exit_scope(c);
             return ERROR;
         }
+        compiler_pop_fblock(c, STOP_ITERATION, start);
     }
     PyCodeObject *co = optimize_and_assemble(c, 1);
     compiler_exit_scope(c);
diff --git a/Python/flowgraph.c b/Python/flowgraph.c
index 83768023a4d870..9a9689f6492a3b 100644
--- a/Python/flowgraph.c
+++ b/Python/flowgraph.c
@@ -263,7 +263,7 @@ basicblock_insert_instruction(basicblock *block, int pos, cfg_instr *instr) {
 }
 
 /* For debugging purposes only */
-#if 0
+#if 1
 static void
 dump_instr(cfg_instr *i)
 {

From 058faa3c6b78ac5d6c3e53120109261d3a6cc5cb Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Sat, 27 Apr 2024 16:23:32 +0000
Subject: [PATCH 2/7] =?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

---
 .../2024-04-27-16-23-29.gh-issue-116767.z9UFpr.rst               | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Core and Builtins/2024-04-27-16-23-29.gh-issue-116767.z9UFpr.rst

diff --git a/Misc/NEWS.d/next/Core and Builtins/2024-04-27-16-23-29.gh-issue-116767.z9UFpr.rst b/Misc/NEWS.d/next/Core and Builtins/2024-04-27-16-23-29.gh-issue-116767.z9UFpr.rst
new file mode 100644
index 00000000000000..cec2041d12ee15
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2024-04-27-16-23-29.gh-issue-116767.z9UFpr.rst	
@@ -0,0 +1 @@
+Fix crash in compiler on 'async with' that has many context managers.

From 4e4328fc75b0bae2b27ad9fea99b6359e0769e99 Mon Sep 17 00:00:00 2001
From: Irit Katriel <iritkatriel@yahoo.com>
Date: Sat, 27 Apr 2024 18:39:46 +0100
Subject: [PATCH 3/7] revert debug thing

---
 Python/flowgraph.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Python/flowgraph.c b/Python/flowgraph.c
index 9a9689f6492a3b..83768023a4d870 100644
--- a/Python/flowgraph.c
+++ b/Python/flowgraph.c
@@ -263,7 +263,7 @@ basicblock_insert_instruction(basicblock *block, int pos, cfg_instr *instr) {
 }
 
 /* For debugging purposes only */
-#if 1
+#if 0
 static void
 dump_instr(cfg_instr *i)
 {

From 42a752fafe45adc4690ed257d6b2db61321a4e95 Mon Sep 17 00:00:00 2001
From: Irit Katriel <iritkatriel@yahoo.com>
Date: Sat, 27 Apr 2024 19:47:13 +0100
Subject: [PATCH 4/7] fix test

---
 Lib/test/test_syntax.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index 491cd8bb7daa42..a0743782519173 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -2418,12 +2418,13 @@ async def bug():
             return "".join(code)
 
         CO_MAXBLOCKS = 20  # static nesting limit of the compiler
+        MAX_MANAGERS = CO_MAXBLOCKS - 1  # One for the StopIteration block
 
-        for n in range(CO_MAXBLOCKS):
+        for n in range(MAX_MANAGERS):
             with self.subTest(f"within range: {n=}"):
                 compile(get_code(n), "<string>", "exec")
 
-        for n in range(CO_MAXBLOCKS, CO_MAXBLOCKS + 5):
+        for n in range(MAX_MANAGERS, MAX_MANAGERS + 5):
             with self.subTest(f"out of range: {n=}"):
                 self._check_error(get_code(n), "too many statically nested blocks")
 

From 2e8aab2bc7784a253b3fdb5c381c553eb706eaed Mon Sep 17 00:00:00 2001
From: Irit Katriel <iritkatriel@yahoo.com>
Date: Sat, 27 Apr 2024 21:15:21 +0100
Subject: [PATCH 5/7] fix other test

---
 Lib/test/test_syntax.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index a0743782519173..c9f2714c0bbce4 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -2393,12 +2393,13 @@ def bug():
             return code
 
         CO_MAXBLOCKS = 20  # static nesting limit of the compiler
+        MAX_MANAGERS = CO_MAXBLOCKS - 1  # One for the StopIteration block
 
-        for n in range(CO_MAXBLOCKS):
+        for n in range(MAX_MANAGERS):
             with self.subTest(f"within range: {n=}"):
                 compile(get_code(n), "<string>", "exec")
 
-        for n in range(CO_MAXBLOCKS, CO_MAXBLOCKS + 5):
+        for n in range(MAX_MANAGERS, MAX_MANAGERS + 5):
             with self.subTest(f"out of range: {n=}"):
                 self._check_error(get_code(n), "too many statically nested blocks")
 

From f29d7bf02e642096cd8b2c8fe3160a890cd45031 Mon Sep 17 00:00:00 2001
From: Irit Katriel <iritkatriel@yahoo.com>
Date: Mon, 29 Apr 2024 17:03:25 +0100
Subject: [PATCH 6/7] increment CO_MAXBLOCKS

---
 Include/cpython/code.h  | 2 +-
 Lib/test/test_syntax.py | 7 ++++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/Include/cpython/code.h b/Include/cpython/code.h
index b0e226e0e1971a..ef8f9304ccab56 100644
--- a/Include/cpython/code.h
+++ b/Include/cpython/code.h
@@ -226,7 +226,7 @@ struct PyCodeObject _PyCode_DEF(1);
 */
 #define PY_PARSER_REQUIRES_FUTURE_KEYWORD
 
-#define CO_MAXBLOCKS 20 /* Max static block nesting within a function */
+#define CO_MAXBLOCKS 21 /* Max static block nesting within a function */
 
 PyAPI_DATA(PyTypeObject) PyCode_Type;
 
diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index c9f2714c0bbce4..de783f714509a3 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -2392,7 +2392,7 @@ def bug():
             code += "): yield a"
             return code
 
-        CO_MAXBLOCKS = 20  # static nesting limit of the compiler
+        CO_MAXBLOCKS = 21  # static nesting limit of the compiler
         MAX_MANAGERS = CO_MAXBLOCKS - 1  # One for the StopIteration block
 
         for n in range(MAX_MANAGERS):
@@ -2418,7 +2418,7 @@ async def bug():
             code.append("): yield a")
             return "".join(code)
 
-        CO_MAXBLOCKS = 20  # static nesting limit of the compiler
+        CO_MAXBLOCKS = 21  # static nesting limit of the compiler
         MAX_MANAGERS = CO_MAXBLOCKS - 1  # One for the StopIteration block
 
         for n in range(MAX_MANAGERS):
@@ -2563,7 +2563,8 @@ def test_syntax_error_on_deeply_nested_blocks(self):
                   while 20:
                    while 21:
                     while 22:
-                     break
+                     while 23:
+                      break
 """
         self._check_error(source, "too many statically nested blocks")
 

From 39d64f2e8fe1e46a18eaf2d225c7bb0bcee4175e Mon Sep 17 00:00:00 2001
From: Irit Katriel <iritkatriel@yahoo.com>
Date: Mon, 29 Apr 2024 17:09:07 +0100
Subject: [PATCH 7/7] calculate once

---
 Python/compile.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Python/compile.c b/Python/compile.c
index 370c773cad70a6..4e94f9297a32d1 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -2237,7 +2237,8 @@ compiler_function_body(struct compiler *c, stmt_ty s, int is_async, Py_ssize_t f
 
     NEW_JUMP_TARGET_LABEL(c, start);
     USE_LABEL(c, start);
-    if (c->u->u_ste->ste_coroutine || c->u->u_ste->ste_generator) {
+    bool add_stopiteration_handler = c->u->u_ste->ste_coroutine || c->u->u_ste->ste_generator;
+    if (add_stopiteration_handler) {
         /* wrap_in_stopiteration_handler will push a block, so we need to account for that */
         RETURN_IF_ERROR(
             compiler_push_fblock(c, NO_LOCATION, STOP_ITERATION,
@@ -2247,7 +2248,7 @@ compiler_function_body(struct compiler *c, stmt_ty s, int is_async, Py_ssize_t f
     for (Py_ssize_t i = first_instr; i < asdl_seq_LEN(body); i++) {
         VISIT_IN_SCOPE(c, stmt, (stmt_ty)asdl_seq_GET(body, i));
     }
-    if (c->u->u_ste->ste_coroutine || c->u->u_ste->ste_generator) {
+    if (add_stopiteration_handler) {
         if (wrap_in_stopiteration_handler(c) < 0) {
             compiler_exit_scope(c);
             return ERROR;