user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Auto merge of #12496 - Jacherr:issue-12492, r=blyxyas

Browse source 
Disable `cast_lossless` when casting to u128 from any (u)int type

Fixes https://github.com/rust-lang/rust-clippy/issues/12492

Disables `cast_lossless` when casting to u128 from any int or uint type. The lint states that when casting to any int type, there can potentially be lossy behaviour if the source type ever exceeds the size of the destination type in the future, which is impossible with a destination of u128.

It's possible this is a bit of a niche edge case which is better addressed by just disabling the lint in code, but I personally couldn't think of any good reason to still lint in this specific case - maybe except if the source is a bool, for readability reasons :).

changelog: FP: `cast_lossless`: disable lint when casting to u128 from any (u)int type
This commit is contained in:
bors 2024-03-20 23:08:45 +00:00
commit 34766a6792
4 changed files with 39 additions and 24 deletions
Download patch file Download diff file Expand all files Collapse all files

7
clippy_lints/src/casts/cast_lossless.rs
View file

@ -6,7 +6,7 @@ use clippy_utils::ty::is_isize_or_usize;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind, QPath, TyKind};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, FloatTy, Ty};
use rustc_middle::ty::{self, FloatTy, Ty, UintTy};
use super::{utils, CAST_LOSSLESS};
@ -77,7 +77,10 @@ pub(super) fn check(
fn should_lint(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>, msrv: &Msrv) -> bool {
// Do not suggest using From in consts/statics until it is valid to do so (see #2267).
if in_constant(cx, expr.hir_id) {
//
// If destination is u128, do not lint because source type cannot be larger
// If source is bool, still lint due to the lint message differing (refers to style)
if in_constant(cx, expr.hir_id) || (!cast_from.is_bool() && matches!(cast_to.kind(), ty::Uint(UintTy::U128))) {
return false;
}