clippy_lints/src/semicolon_block.rs

   1 use clippy_utils::diagnostics::{multispan_sugg_with_applicability, span_lint_and_then};
   2 use rustc_errors::Applicability;
   3 use rustc_hir::{Block, Expr, ExprKind, Stmt, StmtKind};
   4 use rustc_lint::{LateContext, LateLintPass, LintContext};
   5 use rustc_session::{declare_lint_pass, declare_tool_lint};
   6 use rustc_span::Span;
   7
   8 declare_clippy_lint! {
   9     /// ### What it does
  10     ///
  11     /// Suggests moving the semicolon after a block to the inside of the block, after its last
  12     /// expression.
  13     ///
  14     /// ### Why is this bad?
  15     ///
  16     /// For consistency it's best to have the semicolon inside/outside the block. Either way is fine
  17     /// and this lint suggests inside the block.
  18     /// Take a look at `semicolon_outside_block` for the other alternative.
  19     ///
  20     /// ### Example
  21     ///
  22     /// ```rust
  23     /// # fn f(_: u32) {}
  24     /// # let x = 0;
  25     /// unsafe { f(x) };
  26     /// ```
  27     /// Use instead:
  28     /// ```rust
  29     /// # fn f(_: u32) {}
  30     /// # let x = 0;
  31     /// unsafe { f(x); }
  32     /// ```
  33     #[clippy::version = "1.66.0"]
  34     pub SEMICOLON_INSIDE_BLOCK,
  35     restriction,
  36     "add a semicolon inside the block"
  37 }
  38 declare_clippy_lint! {
  39     /// ### What it does
  40     ///
  41     /// Suggests moving the semicolon from a block's final expression outside of the block.
  42     ///
  43     /// ### Why is this bad?
  44     ///
  45     /// For consistency it's best to have the semicolon inside/outside the block. Either way is fine
  46     /// and this lint suggests outside the block.
  47     /// Take a look at `semicolon_inside_block` for the other alternative.
  48     ///
  49     /// ### Example
  50     ///
  51     /// ```rust
  52     /// # fn f(_: u32) {}
  53     /// # let x = 0;
  54     /// unsafe { f(x); }
  55     /// ```
  56     /// Use instead:
  57     /// ```rust
  58     /// # fn f(_: u32) {}
  59     /// # let x = 0;
  60     /// unsafe { f(x) };
  61     /// ```
  62     #[clippy::version = "1.66.0"]
  63     pub SEMICOLON_OUTSIDE_BLOCK,
  64     restriction,
  65     "add a semicolon outside the block"
  66 }
  67 declare_lint_pass!(SemicolonBlock => [SEMICOLON_INSIDE_BLOCK, SEMICOLON_OUTSIDE_BLOCK]);
  68
  69 impl LateLintPass<'_> for SemicolonBlock {
  70     fn check_stmt(&mut self, cx: &LateContext<'_>, stmt: &Stmt<'_>) {
  71         match stmt.kind {
  72             StmtKind::Expr(Expr {
  73                 kind: ExprKind::Block(block, _),
  74                 ..
  75             }) if !block.span.from_expansion() => {
  76                 let Block {
  77                     expr: None,
  78                     stmts: [.., stmt],
  79                     ..
  80                 } = block else { return };
  81                 let &Stmt {
  82                     kind: StmtKind::Semi(expr),
  83                     span,
  84                     ..
  85                 } = stmt else { return };
  86                 semicolon_outside_block(cx, block, expr, span);
  87             },
  88             StmtKind::Semi(Expr {
  89                 kind: ExprKind::Block(block @ Block { expr: Some(tail), .. }, _),
  90                 ..
  91             }) if !block.span.from_expansion() => semicolon_inside_block(cx, block, tail, stmt.span),
  92             _ => (),
  93         }
  94     }
  95 }
  96
  97 fn semicolon_inside_block(cx: &LateContext<'_>, block: &Block<'_>, tail: &Expr<'_>, semi_span: Span) {
  98     let insert_span = tail.span.source_callsite().shrink_to_hi();
  99     let remove_span = semi_span.with_lo(block.span.hi());
 100
 101     span_lint_and_then(
 102         cx,
 103         SEMICOLON_INSIDE_BLOCK,
 104         semi_span,
 105         "consider moving the `;` inside the block for consistent formatting",
 106         |diag| {
 107             multispan_sugg_with_applicability(
 108                 diag,
 109                 "put the `;` here",
 110                 Applicability::MachineApplicable,
 111                 [(remove_span, String::new()), (insert_span, ";".to_owned())],
 112             );
 113         },
 114     );
 115 }
 116
 117 fn semicolon_outside_block(cx: &LateContext<'_>, block: &Block<'_>, tail_stmt_expr: &Expr<'_>, semi_span: Span) {
 118     let insert_span = block.span.with_lo(block.span.hi());
 119     // account for macro calls
 120     let semi_span = cx.sess().source_map().stmt_span(semi_span, block.span);
 121     let remove_span = semi_span.with_lo(tail_stmt_expr.span.source_callsite().hi());
 122
 123     span_lint_and_then(
 124         cx,
 125         SEMICOLON_OUTSIDE_BLOCK,
 126         block.span,
 127         "consider moving the `;` outside the block for consistent formatting",
 128         |diag| {
 129             multispan_sugg_with_applicability(
 130                 diag,
 131                 "put the `;` here",
 132                 Applicability::MachineApplicable,
 133                 [(remove_span, String::new()), (insert_span, ";".to_owned())],
 134             );
 135         },
 136     );
 137 }