Skip to content

feat: support constant folding in ExpressionChecker.check_str_format_call [1/1] #19977

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 3 commits into from
Oct 2, 2025
Merged

feat: support constant folding in ExpressionChecker.check_str_format_call [1/1] #19977

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
a642928
[mypyc] feat: support constant folding in `ExpressionChecker.check_st…
BobTheBuidler Oct 2, 2025
1f894a9
Update checkexpr.py
BobTheBuidler Oct 2, 2025
c21bb26
Update checkexpr.py
BobTheBuidler Oct 2, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 5 additions & 3 deletions mypy/checkexpr.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
from mypy.checker_shared import ExpressionCheckerSharedApi
from mypy.checkmember import analyze_member_access, has_operator
from mypy.checkstrformat import StringFormatterChecker
from mypy.constant_fold import constant_fold_expr
from mypy.erasetype import erase_type, remove_instance_last_known_values, replace_meta_vars
from mypy.errors import ErrorInfo, ErrorWatcher, report_internal_error
from mypy.expandtype import (
Expand Down Expand Up @@ -656,11 +657,12 @@ def visit_call_expr_inner(self, e: CallExpr, allow_none_return: bool = False) ->
return ret_type

def check_str_format_call(self, e: CallExpr) -> None:
"""More precise type checking for str.format() calls on literals."""
"""More precise type checking for str.format() calls on literals and folded constants."""
assert isinstance(e.callee, MemberExpr)
format_value = None
if isinstance(e.callee.expr, StrExpr):
format_value = e.callee.expr.value
folded_callee_expr = constant_fold_expr(e.callee.expr, "<unused>")
if isinstance(folded_callee_expr, str):
format_value = folded_callee_expr
elif self.chk.has_type(e.callee.expr):
typ = get_proper_type(self.chk.lookup_type(e.callee.expr))
if (
Expand Down