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Auto merge of #8183 - alex-ozdemir:limit-ident, r=camsteffen

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Limit the ``[`identity_op`]`` lint to integral operands.

changelog: limit ``[`identity_op`]`` to integral operands

In the ``[`identity_op`]`` lint, if the operands are non-integers, then the lint is likely
wrong.
This commit is contained in:
bors 2021-12-28 22:01:57 +00:00
commit 16ef044e72
4 changed files with 56 additions and 18 deletions
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15
clippy_lints/src/identity_op.rs
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@ -61,15 +61,18 @@ impl<'tcx> LateLintPass<'tcx> for IdentityOp {
}
fn is_allowed(cx: &LateContext<'_>, cmp: BinOp, left: &Expr<'_>, right: &Expr<'_>) -> bool {
// `1 << 0` is a common pattern in bit manipulation code
cmp.node == BinOpKind::Shl
&& constant_simple(cx, cx.typeck_results(), right) == Some(Constant::Int(0))
&& constant_simple(cx, cx.typeck_results(), left) == Some(Constant::Int(1))
// This lint applies to integers
!cx.typeck_results().expr_ty(left).peel_refs().is_integral()
|| !cx.typeck_results().expr_ty(right).peel_refs().is_integral()
// `1 << 0` is a common pattern in bit manipulation code
|| (cmp.node == BinOpKind::Shl
&& constant_simple(cx, cx.typeck_results(), right) == Some(Constant::Int(0))
&& constant_simple(cx, cx.typeck_results(), left) == Some(Constant::Int(1)))
}
fn check(cx: &LateContext<'_>, e: &Expr<'_>, m: i8, span: Span, arg: Span) {
if let Some(Constant::Int(v)) = constant_simple(cx, cx.typeck_results(), e) {
let check = match *cx.typeck_results().expr_ty(e).kind() {
if let Some(Constant::Int(v)) = constant_simple(cx, cx.typeck_results(), e).map(Constant::peel_refs) {
let check = match *cx.typeck_results().expr_ty(e).peel_refs().kind() {
ty::Int(ity) => unsext(cx.tcx, -1_i128, ity),
ty::Uint(uty) => clip(cx.tcx, !0, uty),
_ => return,