src/tools/clippy/clippy_lints/src/dbg_macro.rs

   1 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_sugg};
   2 use clippy_utils::source::snippet_opt;
   3 use rustc_ast::ast;
   4 use rustc_ast::tokenstream::TokenStream;
   5 use rustc_errors::Applicability;
   6 use rustc_lint::{EarlyContext, EarlyLintPass};
   7 use rustc_session::{declare_lint_pass, declare_tool_lint};
   8 use rustc_span::source_map::Span;
   9
  10 declare_clippy_lint! {
  11     /// **What it does:** Checks for usage of dbg!() macro.
  12     ///
  13     /// **Why is this bad?** `dbg!` macro is intended as a debugging tool. It
  14     /// should not be in version control.
  15     ///
  16     /// **Known problems:** None.
  17     ///
  18     /// **Example:**
  19     /// ```rust,ignore
  20     /// // Bad
  21     /// dbg!(true)
  22     ///
  23     /// // Good
  24     /// true
  25     /// ```
  26     pub DBG_MACRO,
  27     restriction,
  28     "`dbg!` macro is intended as a debugging tool"
  29 }
  30
  31 declare_lint_pass!(DbgMacro => [DBG_MACRO]);
  32
  33 impl EarlyLintPass for DbgMacro {
  34     fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::MacCall) {
  35         if mac.path == sym!(dbg) {
  36             if let Some(sugg) = tts_span(mac.args.inner_tokens()).and_then(|span| snippet_opt(cx, span)) {
  37                 span_lint_and_sugg(
  38                     cx,
  39                     DBG_MACRO,
  40                     mac.span(),
  41                     "`dbg!` macro is intended as a debugging tool",
  42                     "ensure to avoid having uses of it in version control",
  43                     sugg,
  44                     Applicability::MaybeIncorrect,
  45                 );
  46             } else {
  47                 span_lint_and_help(
  48                     cx,
  49                     DBG_MACRO,
  50                     mac.span(),
  51                     "`dbg!` macro is intended as a debugging tool",
  52                     None,
  53                     "ensure to avoid having uses of it in version control",
  54                 );
  55             }
  56         }
  57     }
  58 }
  59
  60 // Get span enclosing entire the token stream.
  61 fn tts_span(tts: TokenStream) -> Option<Span> {
  62     let mut cursor = tts.into_trees();
  63     let first = cursor.next()?.span();
  64     let span = cursor.last().map_or(first, |tree| first.to(tree.span()));
  65     Some(span)
  66 }