src/tools/clippy/clippy_lints/src/utils/internal_lints/outer_expn_data_pass.rs

   1 use clippy_utils::diagnostics::span_lint_and_sugg;
   2 use clippy_utils::ty::match_type;
   3 use clippy_utils::{is_lint_allowed, method_calls, paths};
   4 use if_chain::if_chain;
   5 use rustc_errors::Applicability;
   6 use rustc_hir as hir;
   7 use rustc_lint::{LateContext, LateLintPass};
   8 use rustc_session::{declare_lint_pass, declare_tool_lint};
   9 use rustc_span::symbol::Symbol;
  10
  11 declare_clippy_lint! {
  12     /// ### What it does
  13     /// Checks for calls to `cx.outer().expn_data()` and suggests to use
  14     /// the `cx.outer_expn_data()`
  15     ///
  16     /// ### Why is this bad?
  17     /// `cx.outer_expn_data()` is faster and more concise.
  18     ///
  19     /// ### Example
  20     /// ```rust,ignore
  21     /// expr.span.ctxt().outer().expn_data()
  22     /// ```
  23     ///
  24     /// Use instead:
  25     /// ```rust,ignore
  26     /// expr.span.ctxt().outer_expn_data()
  27     /// ```
  28     pub OUTER_EXPN_EXPN_DATA,
  29     internal,
  30     "using `cx.outer_expn().expn_data()` instead of `cx.outer_expn_data()`"
  31 }
  32
  33 declare_lint_pass!(OuterExpnDataPass => [OUTER_EXPN_EXPN_DATA]);
  34
  35 impl<'tcx> LateLintPass<'tcx> for OuterExpnDataPass {
  36     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
  37         if is_lint_allowed(cx, OUTER_EXPN_EXPN_DATA, expr.hir_id) {
  38             return;
  39         }
  40
  41         let (method_names, arg_lists, spans) = method_calls(expr, 2);
  42         let method_names: Vec<&str> = method_names.iter().map(Symbol::as_str).collect();
  43         if_chain! {
  44             if let ["expn_data", "outer_expn"] = method_names.as_slice();
  45             let (self_arg, args) = arg_lists[1];
  46             if args.is_empty();
  47             let self_ty = cx.typeck_results().expr_ty(self_arg).peel_refs();
  48             if match_type(cx, self_ty, &paths::SYNTAX_CONTEXT);
  49             then {
  50                 span_lint_and_sugg(
  51                     cx,
  52                     OUTER_EXPN_EXPN_DATA,
  53                     spans[1].with_hi(expr.span.hi()),
  54                     "usage of `outer_expn().expn_data()`",
  55                     "try",
  56                     "outer_expn_data()".to_string(),
  57                     Applicability::MachineApplicable,
  58                 );
  59             }
  60         }
  61     }
  62 }