[verbose-decimal-constructor (FURB157)] doesn't trigger on Decimal("1_000")

[monosans]

Decimal(1000)  # OK
Decimal(1_000)  # OK
Decimal("1000")  # Triggers FURB157
Decimal("1_000")  # Should trigger FURB157 and become Decimal(1_000), but it doesn't

ruff v0.7.0

[AlexWaygood]

It seems like the parsing we do here is too naive:

ruff/crates/ruff_linter/src/rules/refurb/rules/verbose_decimal_constructor.rs

Lines 77 to 98 in 4ecfe95

	// Parse the inner string as an integer.
	let trimmed = str_literal.to_str().trim_whitespace();
	// Extract the unary sign, if any.
	let (unary, rest) = if let Some(trimmed) = trimmed.strip_prefix('+') {
	("+", trimmed)
	} else if let Some(trimmed) = trimmed.strip_prefix('-') {
	("-", trimmed)
	} else {
	("", trimmed)
	};
	// Skip leading zeros.
	let rest = rest.trim_start_matches('0');
	// Verify that the rest of the string is a valid integer.
	if !rest.chars().all(|c| c.is_ascii_digit()) {
	return;
	};
	// If all the characters are zeros, then the value is zero.
	let rest = if rest.is_empty() { "0" } else { rest };

[AlexWaygood]

If there are more edge cases that we don't handle, it might be worth just using ruff_python_parser::parse_expression to determine if the contents of the string can be parsed as an int literal, rather than reimplementing all the edge cases in the linter. If this is the only edge case we don't currently handle, however, it may be best to avoid doing that and just reimplement the logic in the linter -- using the ruff_python_parser function might be comparatively quite expensive.

[dscorbett]

Decimal accepts more integer-valued strings than are valid as int literals. For example, Decimal("1__2") and Decimal("_1_") and Decimal("١٢٣") are valid. Should FURB157 trigger on those? If so, ruff_python_parser::parse_expression would not be enough.

[dylwil3]

Looks like this is the official regex:

https://github.com/python/cpython/blob/322f14eeff9e3b5853eaac3233f7580ca0214cf8/Lib/_pydecimal.py#L6059-L6077

I can try to take this sometime this weekend (but if I don't, others should feel free to go for it!)