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[3.12] gh-119666: fix multiple class-scope comprehensions referencing __class__ (GH-120295) #120300

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Merged
merged 1 commit into from
Jun 10, 2024
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[3.12] gh-119666: fix multiple class-scope comprehensions referencing __class__ (GH-120295) #120300

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25 changes: 25 additions & 0 deletions Lib/test/test_listcomps.py
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Original file line number Diff line number Diff line change
Expand Up @@ -168,6 +168,31 @@ def test_references___class__(self):
"""
self._check_in_scopes(code, raises=NameError)

def test_references___class___defined(self):
code = """
__class__ = 2
res = [__class__ for x in [1]]
"""
self._check_in_scopes(
code, outputs={"res": [2]}, scopes=["module", "function"])
self._check_in_scopes(code, raises=NameError, scopes=["class"])

def test_references___class___enclosing(self):
code = """
__class__ = 2
class C:
res = [__class__ for x in [1]]
res = C.res
"""
self._check_in_scopes(code, raises=NameError)

def test_super_and_class_cell_in_sibling_comps(self):
code = """
[super for _ in [1]]
[__class__ for _ in [1]]
"""
self._check_in_scopes(code, raises=NameError)

def test_inner_cell_shadows_outer(self):
code = """
items = [(lambda: i) for i in range(5)]
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core and Builtins/2024-06-09-19-13-38.gh-issue-119666.S0G4rZ.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Fix a compiler crash in the case where two comprehensions in class scope both reference ``__class__``.
23 changes: 10 additions & 13 deletions Python/symtable.c
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Original file line number Diff line number Diff line change
Expand Up @@ -675,22 +675,19 @@ inline_comprehension(PySTEntryObject *ste, PySTEntryObject *comp,
if (existing == NULL && PyErr_Occurred()) {
return 0;
}
// __class__ is never allowed to be free through a class scope (see
// drop_class_free)
if (scope == FREE && ste->ste_type == ClassBlock &&
_PyUnicode_EqualToASCIIString(k, "__class__")) {
scope = GLOBAL_IMPLICIT;
if (PySet_Discard(comp_free, k) < 0) {
return 0;
}
remove_dunder_class = 1;
}
if (!existing) {
// name does not exist in scope, copy from comprehension
assert(scope != FREE || PySet_Contains(comp_free, k) == 1);
if (scope == FREE && ste->ste_type == ClassBlock &&
_PyUnicode_EqualToASCIIString(k, "__class__")) {
// if __class__ is unbound in the enclosing class scope and free
// in the comprehension scope, it needs special handling; just
// letting it be marked as free in class scope will break due to
// drop_class_free
scope = GLOBAL_IMPLICIT;
only_flags &= ~DEF_FREE;
if (PySet_Discard(comp_free, k) < 0) {
return 0;
}
remove_dunder_class = 1;
}
PyObject *v_flags = PyLong_FromLong(only_flags);
if (v_flags == NULL) {
return 0;
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