Skip to content

Commit

Permalink
pythongh-104374: Remove access to class scopes for inlined comprehens…
Browse files Browse the repository at this point in the history 
…ions (python#104528)

Co-authored-by: Carl Meyer <[email protected]>
  • Loading branch information
@JelleZijlstra @carljm
JelleZijlstra and carljm authored May 18, 2023
1 parent 152227b commit 662aede
Show file tree
Hide file tree
Showing 3 changed files with 125 additions and 9 deletions.
109 changes: 107 additions & 2 deletions Lib/test/test_listcomps.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -200,7 +200,8 @@ def f():
y = [g for x in [1]]
"""
outputs = {"y": [2]}
self._check_in_scopes(code, outputs)
self._check_in_scopes(code, outputs, scopes=["module", "function"])
self._check_in_scopes(code, scopes=["class"], raises=NameError)

def test_inner_cell_shadows_outer_redefined(self):
code = """
Expand Down Expand Up @@ -328,7 +329,8 @@ def test_nested_2(self):
y = [x for [x ** x for x in range(x)][x - 1] in l]
"""
outputs = {"y": [3, 3, 3]}
self._check_in_scopes(code, outputs)
self._check_in_scopes(code, outputs, scopes=["module", "function"])
self._check_in_scopes(code, scopes=["class"], raises=NameError)

def test_nested_3(self):
code = """
Expand Down Expand Up @@ -379,6 +381,109 @@ def f():
with self.assertRaises(UnboundLocalError):
f()

def test_name_error_in_class_scope(self):
code = """
y = 1
[x + y for x in range(2)]
"""
self._check_in_scopes(code, raises=NameError, scopes=["class"])

def test_global_in_class_scope(self):
code = """
y = 2
vals = [(x, y) for x in range(2)]
"""
outputs = {"vals": [(0, 1), (1, 1)]}
self._check_in_scopes(code, outputs, ns={"y": 1}, scopes=["class"])

def test_in_class_scope_inside_function_1(self):
code = """
class C:
y = 2
vals = [(x, y) for x in range(2)]
vals = C.vals
"""
outputs = {"vals": [(0, 1), (1, 1)]}
self._check_in_scopes(code, outputs, ns={"y": 1}, scopes=["function"])

def test_in_class_scope_inside_function_2(self):
code = """
y = 1
class C:
y = 2
vals = [(x, y) for x in range(2)]
vals = C.vals
"""
outputs = {"vals": [(0, 1), (1, 1)]}
self._check_in_scopes(code, outputs, scopes=["function"])

def test_in_class_scope_with_global(self):
code = """
y = 1
class C:
global y
y = 2
# Ensure the listcomp uses the global, not the value in the
# class namespace
locals()['y'] = 3
vals = [(x, y) for x in range(2)]
vals = C.vals
"""
outputs = {"vals": [(0, 2), (1, 2)]}
self._check_in_scopes(code, outputs, scopes=["module", "class"])
outputs = {"vals": [(0, 1), (1, 1)]}
self._check_in_scopes(code, outputs, scopes=["function"])

def test_in_class_scope_with_nonlocal(self):
code = """
y = 1
class C:
nonlocal y
y = 2
# Ensure the listcomp uses the global, not the value in the
# class namespace
locals()['y'] = 3
vals = [(x, y) for x in range(2)]
vals = C.vals
"""
outputs = {"vals": [(0, 2), (1, 2)]}
self._check_in_scopes(code, outputs, scopes=["function"])

def test_nested_has_free_var(self):
code = """
items = [a for a in [1] if [a for _ in [0]]]
"""
outputs = {"items": [1]}
self._check_in_scopes(code, outputs, scopes=["class"])

def test_nested_free_var_not_bound_in_outer_comp(self):
code = """
z = 1
items = [a for a in [1] if [x for x in [1] if z]]
"""
self._check_in_scopes(code, {"items": [1]}, scopes=["module", "function"])
self._check_in_scopes(code, {"items": []}, ns={"z": 0}, scopes=["class"])

def test_nested_free_var_in_iter(self):
code = """
items = [_C for _C in [1] for [0, 1][[x for x in [1] if _C][0]] in [2]]
"""
self._check_in_scopes(code, {"items": [1]})

def test_nested_free_var_in_expr(self):
code = """
items = [(_C, [x for x in [1] if _C]) for _C in [0, 1]]
"""
self._check_in_scopes(code, {"items": [(0, []), (1, [1])]})

def test_nested_listcomp_in_lambda(self):
code = """
f = [(z, lambda y: [(x, y, z) for x in [3]]) for z in [1]]
(z, func), = f
out = func(2)
"""
self._check_in_scopes(code, {"z": 1, "out": [(3, 2, 1)]})


__test__ = {'doctests' : doctests}

Expand Down
20 changes: 15 additions & 5 deletions Python/compile.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -388,6 +388,8 @@ struct compiler_unit {
instr_sequence u_instr_sequence; /* codegen output */

int u_nfblocks;
int u_in_inlined_comp;

struct fblockinfo u_fblock[CO_MAXBLOCKS];

_PyCompile_CodeUnitMetadata u_metadata;
Expand Down Expand Up @@ -1290,6 +1292,7 @@ compiler_enter_scope(struct compiler *c, identifier name,
}

u->u_nfblocks = 0;
u->u_in_inlined_comp = 0;
u->u_metadata.u_firstlineno = lineno;
u->u_metadata.u_consts = PyDict_New();
if (!u->u_metadata.u_consts) {
Expand Down Expand Up @@ -4137,7 +4140,7 @@ compiler_nameop(struct compiler *c, location loc,
case OP_DEREF:
switch (ctx) {
case Load:
if (c->u->u_ste->ste_type == ClassBlock) {
if (c->u->u_ste->ste_type == ClassBlock && !c->u->u_in_inlined_comp) {
op = LOAD_FROM_DICT_OR_DEREF;
// First load the locals
if (codegen_addop_noarg(INSTR_SEQUENCE(c), LOAD_LOCALS, loc) < 0) {
Expand Down Expand Up @@ -4188,7 +4191,12 @@ compiler_nameop(struct compiler *c, location loc,
break;
case OP_NAME:
switch (ctx) {
case Load: op = LOAD_NAME; break;
case Load:
op = (c->u->u_ste->ste_type == ClassBlock
&& c->u->u_in_inlined_comp)
? LOAD_GLOBAL
: LOAD_NAME;
break;
case Store: op = STORE_NAME; break;
case Del: op = DELETE_NAME; break;
}
Expand Down Expand Up @@ -5415,6 +5423,8 @@ push_inlined_comprehension_state(struct compiler *c, location loc,
PySTEntryObject *entry,
inlined_comprehension_state *state)
{
int in_class_block = (c->u->u_ste->ste_type == ClassBlock) && !c->u->u_in_inlined_comp;
c->u->u_in_inlined_comp++;
// iterate over names bound in the comprehension and ensure we isolate
// them from the outer scope as needed
PyObject *k, *v;
Expand All @@ -5426,7 +5436,7 @@ push_inlined_comprehension_state(struct compiler *c, location loc,
// at all; DEF_LOCAL | DEF_NONLOCAL can occur in the case of an
// assignment expression to a nonlocal in the comprehension, these don't
// need handling here since they shouldn't be isolated
if (symbol & DEF_LOCAL && !(symbol & DEF_NONLOCAL)) {
if ((symbol & DEF_LOCAL && !(symbol & DEF_NONLOCAL)) || in_class_block) {
if (!_PyST_IsFunctionLike(c->u->u_ste)) {
// non-function scope: override this name to use fast locals
PyObject *orig = PyDict_GetItem(c->u->u_metadata.u_fasthidden, k);
Expand All @@ -5448,8 +5458,7 @@ push_inlined_comprehension_state(struct compiler *c, location loc,
long scope = (symbol >> SCOPE_OFFSET) & SCOPE_MASK;
PyObject *outv = PyDict_GetItemWithError(c->u->u_ste->ste_symbols, k);
if (outv == NULL) {
assert(PyErr_Occurred());
return ERROR;
outv = _PyLong_GetZero();
}
assert(PyLong_Check(outv));
long outsc = (PyLong_AS_LONG(outv) >> SCOPE_OFFSET) & SCOPE_MASK;
Expand Down Expand Up @@ -5523,6 +5532,7 @@ static int
pop_inlined_comprehension_state(struct compiler *c, location loc,
inlined_comprehension_state state)
{
c->u->u_in_inlined_comp--;
PyObject *k, *v;
Py_ssize_t pos = 0;
if (state.temp_symbols) {
Expand Down
5 changes: 3 additions & 2 deletions Python/symtable.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -674,8 +674,9 @@ inline_comprehension(PySTEntryObject *ste, PySTEntryObject *comp,
}

// free vars in comprehension that are locals in outer scope can
// now simply be locals, unless they are free in comp children
if (!is_free_in_any_child(comp, k)) {
// now simply be locals, unless they are free in comp children,
// or if the outer scope is a class block
if (!is_free_in_any_child(comp, k) && ste->ste_type != ClassBlock) {
if (PySet_Discard(comp_free, k) < 0) {
return 0;
}
Expand Down

0 comments on commit 662aede

Please sign in to comment.