62 lines
1.9 KiB
Rust
62 lines
1.9 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::source::{IntoSpan, SpanRangeExt};
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use rustc_ast::ast::{Expr, ExprKind};
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use rustc_errors::Applicability;
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use rustc_lint::{EarlyContext, EarlyLintPass};
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use rustc_session::declare_lint_pass;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for empty `else` branches.
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///
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/// ### Why is this bad?
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/// An empty else branch does nothing and can be removed.
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///
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/// ### Example
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/// ```no_run
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///# fn check() -> bool { true }
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/// if check() {
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/// println!("Check successful!");
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/// } else {
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/// }
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/// ```
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/// Use instead:
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/// ```no_run
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///# fn check() -> bool { true }
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/// if check() {
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/// println!("Check successful!");
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/// }
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/// ```
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#[clippy::version = "1.72.0"]
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pub NEEDLESS_ELSE,
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style,
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"empty else branch"
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}
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declare_lint_pass!(NeedlessElse => [NEEDLESS_ELSE]);
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impl EarlyLintPass for NeedlessElse {
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fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
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if let ExprKind::If(_, then_block, Some(else_clause)) = &expr.kind
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&& let ExprKind::Block(block, _) = &else_clause.kind
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&& !expr.span.from_expansion()
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&& !else_clause.span.from_expansion()
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&& block.stmts.is_empty()
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&& let range = (then_block.span.hi()..expr.span.hi()).trim_start(cx)
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&& range.clone().check_source_text(cx, |src| {
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// Ignore else blocks that contain comments or #[cfg]s
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!src.contains(['/', '#'])
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})
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{
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span_lint_and_sugg(
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cx,
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NEEDLESS_ELSE,
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range.with_ctxt(expr.span.ctxt()),
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"this `else` branch is empty",
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"you can remove it",
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String::new(),
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Applicability::MachineApplicable,
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);
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}
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}
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}
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