mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-24 12:03:28 +00:00
54 lines
1.9 KiB
Rust
54 lines
1.9 KiB
Rust
|
//! lint on if branches that could be swapped so no `!` operation is necessary on the condition
|
||
|
|
||
|
use rustc::lint::*;
|
||
|
use syntax::attr::*;
|
||
|
use syntax::ast::*;
|
||
|
|
||
|
use utils::span_help_and_lint;
|
||
|
|
||
|
/// **What it does:** Warns on the use of `!` or `!=` in an if condition with an else branch
|
||
|
///
|
||
|
/// **Why is this bad?** Negations reduce the readability of statements
|
||
|
///
|
||
|
/// **Known problems:** None
|
||
|
///
|
||
|
/// **Example:** if !v.is_empty() { a() } else { b() }
|
||
|
declare_lint! {
|
||
|
pub IF_NOT_ELSE, Warn,
|
||
|
"finds if branches that could be swapped so no negation operation is necessary on the condition"
|
||
|
}
|
||
|
|
||
|
pub struct IfNotElse;
|
||
|
|
||
|
impl LintPass for IfNotElse {
|
||
|
fn get_lints(&self) -> LintArray {
|
||
|
lint_array!(IF_NOT_ELSE)
|
||
|
}
|
||
|
}
|
||
|
|
||
|
impl EarlyLintPass for IfNotElse {
|
||
|
fn check_expr(&mut self, cx: &EarlyContext, item: &Expr) {
|
||
|
if let ExprKind::If(ref cond, _, Some(ref els)) = item.node {
|
||
|
if let ExprKind::Block(..) = els.node {
|
||
|
match cond.node {
|
||
|
ExprKind::Unary(UnOp::Not, _) => {
|
||
|
span_help_and_lint(cx,
|
||
|
IF_NOT_ELSE,
|
||
|
item.span,
|
||
|
"Unnecessary boolean `not` operation",
|
||
|
"remove the `!` and swap the blocks of the if/else");
|
||
|
},
|
||
|
ExprKind::Binary(ref kind, _, _) if kind.node == BinOpKind::Ne => {
|
||
|
span_help_and_lint(cx,
|
||
|
IF_NOT_ELSE,
|
||
|
item.span,
|
||
|
"Unnecessary `!=` operation",
|
||
|
"change to `==` and swap the blocks of the if/else");
|
||
|
},
|
||
|
_ => {},
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
}
|