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Refactor if_not_else:

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* Check HIR tree first.
* Merge lint calls.
This commit is contained in:
Jason Newcomb 2024-06-11 14:47:29 -04:00
parent 776a5238b7
commit b26b820f3f
1 changed files with 26 additions and 37 deletions
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63
clippy_lints/src/if_not_else.rs
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@ -56,44 +56,33 @@ fn is_zero_const(expr: &Expr<'_>, cx: &LateContext<'_>) -> bool {
}
impl LateLintPass<'_> for IfNotElse {
fn check_expr(&mut self, cx: &LateContext<'_>, item: &Expr<'_>) {
// While loops will be desugared to ExprKind::If. This will cause the lint to fire.
// To fix this, return early if this span comes from a macro or desugaring.
if item.span.from_expansion() {
return;
}
if let ExprKind::If(cond, _, Some(els)) = item.kind {
if let ExprKind::Block(..) = els.kind {
// Disable firing the lint in "else if" expressions.
if is_else_clause(cx.tcx, item) {
return;
}
fn check_expr(&mut self, cx: &LateContext<'_>, e: &Expr<'_>) {
if let ExprKind::If(cond, _, Some(els)) = e.kind
&& let ExprKind::DropTemps(cond) = cond.kind
&& let ExprKind::Block(..) = els.kind
{
let (msg, help) = match cond.kind {
ExprKind::Unary(UnOp::Not, _) => (
"unnecessary boolean `not` operation",
"remove the `!` and swap the blocks of the `if`/`else`",
),
// Don't lint on `… != 0`, as these are likely to be bit tests.
// For example, `if foo & 0x0F00 != 0 { … } else { … }` is already in the "proper" order.
ExprKind::Binary(op, _, rhs) if op.node == BinOpKind::Ne && !is_zero_const(rhs, cx) => (
"unnecessary `!=` operation",
"change to `==` and swap the blocks of the `if`/`else`",
),
_ => return,
};
match cond.peel_drop_temps().kind {
ExprKind::Unary(UnOp::Not, _) => {
span_lint_and_help(
cx,
IF_NOT_ELSE,
item.span,
"unnecessary boolean `not` operation",
None,
"remove the `!` and swap the blocks of the `if`/`else`",
);
},
ExprKind::Binary(ref kind, _, lhs) if kind.node == BinOpKind::Ne && !is_zero_const(lhs, cx) => {
// Disable firing the lint on `… != 0`, as these are likely to be bit tests.
// For example, `if foo & 0x0F00 != 0 { … } else { … }` already is in the "proper" order.
span_lint_and_help(
cx,
IF_NOT_ELSE,
item.span,
"unnecessary `!=` operation",
None,
"change to `==` and swap the blocks of the `if`/`else`",
);
},
_ => (),
}
// `from_expansion` will also catch `while` loops which appear in the HIR as:
// ```rust
// loop {
// if cond { ... } else { break; }
// }
// ```
if !e.span.from_expansion() && !is_else_clause(cx.tcx, e) {
span_lint_and_help(cx, IF_NOT_ELSE, e.span, msg, None, help);
}
}
}