src/librustc_lint/redundant_semicolon.rs

   1 use crate::{EarlyContext, EarlyLintPass, LintContext};
   2 use rustc_ast::ast::{Block, StmtKind};
   3 use rustc_errors::Applicability;
   4 use rustc_span::Span;
   5
   6 declare_lint! {
   7     pub REDUNDANT_SEMICOLONS,
   8     Warn,
   9     "detects unnecessary trailing semicolons"
  10 }
  11
  12 declare_lint_pass!(RedundantSemicolons => [REDUNDANT_SEMICOLONS]);
  13
  14 impl EarlyLintPass for RedundantSemicolons {
  15     fn check_block(&mut self, cx: &EarlyContext<'_>, block: &Block) {
  16         let mut seq = None;
  17         for stmt in block.stmts.iter() {
  18             match (&stmt.kind, &mut seq) {
  19                 (StmtKind::Empty, None) => seq = Some((stmt.span, false)),
  20                 (StmtKind::Empty, Some(seq)) => *seq = (seq.0.to(stmt.span), true),
  21                 (_, seq) => maybe_lint_redundant_semis(cx, seq),
  22             }
  23         }
  24         maybe_lint_redundant_semis(cx, &mut seq);
  25     }
  26 }
  27
  28 fn maybe_lint_redundant_semis(cx: &EarlyContext<'_>, seq: &mut Option<(Span, bool)>) {
  29     if let Some((span, multiple)) = seq.take() {
  30         cx.struct_span_lint(REDUNDANT_SEMICOLONS, span, |lint| {
  31             let (msg, rem) = if multiple {
  32                 ("unnecessary trailing semicolons", "remove these semicolons")
  33             } else {
  34                 ("unnecessary trailing semicolon", "remove this semicolon")
  35             };
  36             lint.build(msg)
  37                 .span_suggestion(span, rem, String::new(), Applicability::MaybeIncorrect)
  38                 .emit();
  39         });
  40     }
  41 }