From c77b966f8a3972f4ec7881340786e154eafea205 Mon Sep 17 00:00:00 2001
From: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>
Date: Sat, 29 Aug 2026 13:22:25 +0100
Subject: [PATCH] gh-156459: Fix cleanup on error in compiler_set_qualname
 (GH-156462) (cherry picked from commit
 8b082aa405101ab806433cd4d7305b19397271cf)

Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>
---
 Include/internal/pycore_compile.h                     |  1 +
 .../2026-08-27-13-26-50.gh-issue-156459.Z8Zqik.rst    |  3 +++
 Python/codegen.c                                      |  1 +
 Python/compile.c                                      | 11 ++++++-----
 4 files changed, 11 insertions(+), 5 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2026-08-27-13-26-50.gh-issue-156459.Z8Zqik.rst

diff --git a/Include/internal/pycore_compile.h b/Include/internal/pycore_compile.h
index ed776bbb73a0ee9..5a209be9045f7ce 100644
--- a/Include/internal/pycore_compile.h
+++ b/Include/internal/pycore_compile.h
@@ -132,6 +132,7 @@ int _PyCompile_EnterScope(struct _PyCompiler *c, identifier name, int scope_type
                           void *key, int lineno, PyObject *private,
                           _PyCompile_CodeUnitMetadata *umd);
 void _PyCompile_ExitScope(struct _PyCompiler *c);
+int _PyCompile_SetQualname(struct _PyCompiler *c);
 Py_ssize_t _PyCompile_AddConst(struct _PyCompiler *c, PyObject *o);
 _PyInstructionSequence *_PyCompile_InstrSequence(struct _PyCompiler *c);
 int _PyCompile_StartAnnotationSetup(struct _PyCompiler *c);
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-08-27-13-26-50.gh-issue-156459.Z8Zqik.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-08-27-13-26-50.gh-issue-156459.Z8Zqik.rst
new file mode 100644
index 000000000000000..2de2e0e72273c6c
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-08-27-13-26-50.gh-issue-156459.Z8Zqik.rst
@@ -0,0 +1,3 @@
+Fix cleanup on error in ``compiler_set_qualname``. Previously it was called in
+``_PyCompile_EnterScope``, after the scope had been entered, and this was not
+reversed in case of an error.
diff --git a/Python/codegen.c b/Python/codegen.c
index 9649bad4b3dd09a..d95d66da1a3f195 100644
--- a/Python/codegen.c
+++ b/Python/codegen.c
@@ -655,6 +655,7 @@ codegen_enter_scope(compiler *c, identifier name, int scope_type,
 {
     RETURN_IF_ERROR(
         _PyCompile_EnterScope(c, name, scope_type, key, lineno, private, umd));
+    RETURN_IF_ERROR_IN_SCOPE(c, _PyCompile_SetQualname(c));
     location loc = LOCATION(lineno, lineno, 0, 0);
     if (scope_type == COMPILE_SCOPE_MODULE) {
         loc.lineno = 0;
diff --git a/Python/compile.c b/Python/compile.c
index 6c5ef5329ffc3aa..3ce3bb9dcc879ff 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -226,13 +226,17 @@ _PyCompile_MaybeAddStaticAttributeToClass(compiler *c, expr_ty e)
     return SUCCESS;
 }
 
-static int
-compiler_set_qualname(compiler *c)
+int
+_PyCompile_SetQualname(compiler *c)
 {
     Py_ssize_t stack_size;
     struct compiler_unit *u = c->u;
     PyObject *name, *base;
 
+    if (u->u_scope_type == COMPILE_SCOPE_MODULE) {
+        return SUCCESS;
+    }
+
     base = NULL;
     stack_size = PyList_GET_SIZE(c->c_stack);
     assert(stack_size >= 1);
@@ -704,9 +708,6 @@ _PyCompile_EnterScope(compiler *c, identifier name, int scope_type,
     u->u_private = Py_XNewRef(private);
 
     c->u = u;
-    if (scope_type != COMPILE_SCOPE_MODULE) {
-        RETURN_IF_ERROR(compiler_set_qualname(c));
-    }
     return SUCCESS;
 }