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merged 4 commits into from
Aug 28, 2024
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gh-123344: Add missing ast optimizations for PEP 696 #123377

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84ab9a9
Implement desired functionality in ast_opt.c
wrongnull Aug 27, 2024
2082e0e
Add tests
Eclips4 Aug 27, 2024
83f4415
Add news
wrongnull Aug 27, 2024
197c0d4
Update Misc/NEWS.d/next/Core and Builtins/2024-08-27-13-16-40.gh-issu…
wrongnull Aug 28, 2024
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104 changes: 95 additions & 9 deletions Lib/test/test_ast/test_ast.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3062,8 +3062,8 @@ class ASTOptimiziationTests(unittest.TestCase):
def wrap_expr(self, expr):
return ast.Module(body=[ast.Expr(value=expr)])

def wrap_for(self, for_statement):
return ast.Module(body=[for_statement])
def wrap_statement(self, statement):
return ast.Module(body=[statement])

def assert_ast(self, code, non_optimized_target, optimized_target):
non_optimized_tree = ast.parse(code, optimize=-1)
Expand All @@ -3090,16 +3090,16 @@ def assert_ast(self, code, non_optimized_target, optimized_target):
f"{ast.dump(optimized_tree)}",
)

def create_binop(self, operand, left=ast.Constant(1), right=ast.Constant(1)):
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Suggested change
def create_binop(self, operand, left=ast.Constant(1), right=ast.Constant(1)):
def create_binop(self, operand, left=None, right=None):

please, don't use complex objects as defaults

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This seems fine as is; it's more convenient to write many of the remaining tests this way.

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I am in a purist camp :) But, this is minor, I agree. Since these objects aren't ever mutated, this does not introduce any problems.

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Yeah, I also don't like mutable defaults. But this one looks not very complex and it doesn't seem to be mutated anytime soon :) We can rewrite it, but the diff would be much larger

return ast.BinOp(left=left, op=self.binop[operand], right=right)

def test_folding_binop(self):
code = "1 %s 1"
operators = self.binop.keys()

def create_binop(operand, left=ast.Constant(1), right=ast.Constant(1)):
return ast.BinOp(left=left, op=self.binop[operand], right=right)

for op in operators:
result_code = code % op
non_optimized_target = self.wrap_expr(create_binop(op))
non_optimized_target = self.wrap_expr(self.create_binop(op))
optimized_target = self.wrap_expr(ast.Constant(value=eval(result_code)))

with self.subTest(
Expand All @@ -3111,7 +3111,7 @@ def create_binop(operand, left=ast.Constant(1), right=ast.Constant(1)):

# Multiplication of constant tuples must be folded
code = "(1,) * 3"
non_optimized_target = self.wrap_expr(create_binop("*", ast.Tuple(elts=[ast.Constant(value=1)]), ast.Constant(value=3)))
non_optimized_target = self.wrap_expr(self.create_binop("*", ast.Tuple(elts=[ast.Constant(value=1)]), ast.Constant(value=3)))
optimized_target = self.wrap_expr(ast.Constant(eval(code)))

self.assert_ast(code, non_optimized_target, optimized_target)
Expand Down Expand Up @@ -3222,12 +3222,12 @@ def test_folding_iter(self):
]

for left, right, ast_cls, optimized_iter in braces:
non_optimized_target = self.wrap_for(ast.For(
non_optimized_target = self.wrap_statement(ast.For(
target=ast.Name(id="_", ctx=ast.Store()),
iter=ast_cls(elts=[ast.Constant(1)]),
body=[ast.Pass()]
))
optimized_target = self.wrap_for(ast.For(
optimized_target = self.wrap_statement(ast.For(
target=ast.Name(id="_", ctx=ast.Store()),
iter=ast.Constant(value=optimized_iter),
body=[ast.Pass()]
Expand All @@ -3245,6 +3245,92 @@ def test_folding_subscript(self):

self.assert_ast(code, non_optimized_target, optimized_target)

def test_folding_type_param_in_function_def(self):
code = "def foo[%s = 1 + 1](): pass"

unoptimized_binop = self.create_binop("+")
unoptimized_type_params = [
("T", "T", ast.TypeVar),
("**P", "P", ast.ParamSpec),
("*Ts", "Ts", ast.TypeVarTuple),
]

for type, name, type_param in unoptimized_type_params:
result_code = code % type
optimized_target = self.wrap_statement(
ast.FunctionDef(
name='foo',
args=ast.arguments(),
body=[ast.Pass()],
type_params=[type_param(name=name, default_value=ast.Constant(2))]
)
)
non_optimized_target = self.wrap_statement(
ast.FunctionDef(
name='foo',
args=ast.arguments(),
body=[ast.Pass()],
type_params=[type_param(name=name, default_value=unoptimized_binop)]
)
)
self.assert_ast(result_code, non_optimized_target, optimized_target)

def test_folding_type_param_in_class_def(self):
code = "class foo[%s = 1 + 1]: pass"

unoptimized_binop = self.create_binop("+")
unoptimized_type_params = [
("T", "T", ast.TypeVar),
("**P", "P", ast.ParamSpec),
("*Ts", "Ts", ast.TypeVarTuple),
]

for type, name, type_param in unoptimized_type_params:
result_code = code % type
optimized_target = self.wrap_statement(
ast.ClassDef(
name='foo',
body=[ast.Pass()],
type_params=[type_param(name=name, default_value=ast.Constant(2))]
)
)
non_optimized_target = self.wrap_statement(
ast.ClassDef(
name='foo',
body=[ast.Pass()],
type_params=[type_param(name=name, default_value=unoptimized_binop)]
)
)
self.assert_ast(result_code, non_optimized_target, optimized_target)

def test_folding_type_param_in_type_alias(self):
code = "type foo[%s = 1 + 1] = 1"

unoptimized_binop = self.create_binop("+")
unoptimized_type_params = [
("T", "T", ast.TypeVar),
("**P", "P", ast.ParamSpec),
("*Ts", "Ts", ast.TypeVarTuple),
]

for type, name, type_param in unoptimized_type_params:
result_code = code % type
optimized_target = self.wrap_statement(
ast.TypeAlias(
name=ast.Name(id='foo', ctx=ast.Store()),
type_params=[type_param(name=name, default_value=ast.Constant(2))],
value=ast.Constant(value=1),
)
)
non_optimized_target = self.wrap_statement(
ast.TypeAlias(
name=ast.Name(id='foo', ctx=ast.Store()),
type_params=[type_param(name=name, default_value=unoptimized_binop)],
value=ast.Constant(value=1),
)
)
self.assert_ast(result_code, non_optimized_target, optimized_target)


if __name__ == "__main__":
unittest.main()
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core and Builtins/2024-08-27-13-16-40.gh-issue-123344.56Or78.rst
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@@ -0,0 +1 @@
Add AST optimizations for type parameter defaults.
3 changes: 3 additions & 0 deletions Python/ast_opt.c
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Expand Up @@ -1087,10 +1087,13 @@ astfold_type_param(type_param_ty node_, PyArena *ctx_, _PyASTOptimizeState *stat
switch (node_->kind) {
case TypeVar_kind:
CALL_OPT(astfold_expr, expr_ty, node_->v.TypeVar.bound);
CALL_OPT(astfold_expr, expr_ty, node_->v.TypeVar.default_value);
break;
case ParamSpec_kind:
CALL_OPT(astfold_expr, expr_ty, node_->v.ParamSpec.default_value);
break;
case TypeVarTuple_kind:
CALL_OPT(astfold_expr, expr_ty, node_->v.TypeVarTuple.default_value);
break;
}
return 1;
Expand Down
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