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use crate::{lints::RedundantSemicolonsDiag, EarlyContext, EarlyLintPass, LintContext};
use rustc_ast::{Block, StmtKind};
use rustc_span::Span;
declare_lint! {
/// The `redundant_semicolons` lint detects unnecessary trailing
/// semicolons.
///
/// ### Example
///
/// ```rust
/// let _ = 123;;
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// Extra semicolons are not needed, and may be removed to avoid confusion
/// and visual clutter.
pub REDUNDANT_SEMICOLONS,
Warn,
"detects unnecessary trailing semicolons"
}
declare_lint_pass!(RedundantSemicolons => [REDUNDANT_SEMICOLONS]);
impl EarlyLintPass for RedundantSemicolons {
fn check_block(&mut self, cx: &EarlyContext<'_>, block: &Block) {
let mut seq = None;
for stmt in block.stmts.iter() {
match (&stmt.kind, &mut seq) {
(StmtKind::Empty, None) => seq = Some((stmt.span, false)),
(StmtKind::Empty, Some(seq)) => *seq = (seq.0.to(stmt.span), true),
(_, seq) => maybe_lint_redundant_semis(cx, seq),
}
}
maybe_lint_redundant_semis(cx, &mut seq);
}
}
fn maybe_lint_redundant_semis(cx: &EarlyContext<'_>, seq: &mut Option<(Span, bool)>) {
if let Some((span, multiple)) = seq.take() {
// FIXME: Find a better way of ignoring the trailing
// semicolon from macro expansion
if span == rustc_span::DUMMY_SP {
return;
}
cx.emit_spanned_lint(
REDUNDANT_SEMICOLONS,
span,
RedundantSemicolonsDiag { multiple, suggestion: span },
);
}
}
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