clippy_lints/src/dbg_macro.rs

   1 use crate::utils::{span_help_and_lint, span_lint_and_sugg, snippet_opt};
   2 use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
   3 use rustc::{declare_tool_lint, lint_array};
   4 use syntax::ast;
   5 use rustc_errors::Applicability;
   6 use syntax::tokenstream::TokenStream;
   7 use syntax::source_map::Span;
   8
   9 /// **What it does:** Checks for usage of dbg!() macro.
  10 ///
  11 /// **Why is this bad?** `dbg!` macro is intended as a debugging tool. It
  12 /// should not be in version control.
  13 ///
  14 /// **Known problems:** None.
  15 ///
  16 /// **Example:**
  17 /// ```rust,ignore
  18 /// // Bad
  19 /// dbg!(true)
  20 ///
  21 /// // Good
  22 /// true
  23 /// ```
  24 declare_clippy_lint! {
  25     pub DBG_MACRO,
  26     restriction,
  27     "`dbg!` macro is intended as a debugging tool"
  28 }
  29
  30 #[derive(Copy, Clone, Debug)]
  31 pub struct Pass;
  32
  33 impl LintPass for Pass {
  34     fn get_lints(&self) -> LintArray {
  35         lint_array!(DBG_MACRO)
  36     }
  37
  38     fn name(&self) -> &'static str {
  39         "DbgMacro"
  40     }
  41 }
  42
  43 impl EarlyLintPass for Pass {
  44     fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::Mac) {
  45         if mac.node.path == "dbg" {
  46             match tts_span(mac.node.tts.clone()).and_then(|span| snippet_opt(cx, span)) {
  47                 Some(sugg) => {
  48                     span_lint_and_sugg(
  49                         cx,
  50                         DBG_MACRO,
  51                         mac.span,
  52                         "`dbg!` macro is intended as a debugging tool",
  53                         "ensure to avoid having uses of it in version control",
  54                         sugg,
  55                         Applicability::MaybeIncorrect,
  56                     );
  57                 }
  58                 None => {
  59                     span_help_and_lint(
  60                         cx,
  61                         DBG_MACRO,
  62                         mac.span,
  63                         "`dbg!` macro is intended as a debugging tool",
  64                         "ensure to avoid having uses of it in version control",
  65                     );
  66                 }
  67             };
  68         }
  69     }
  70 }
  71
  72 // Get span enclosing entire the token stream.
  73 fn tts_span(tts: TokenStream) -> Option<Span> {
  74     let mut cursor = tts.into_trees();
  75     let first = cursor.next()?.span();
  76     let span = match cursor.last() {
  77         Some(tree) => first.to(tree.span()),
  78         None => first,
  79     };
  80     Some(span)
  81 }