clippy_lints/src/methods/expect_used.rs

   1 use crate::utils::{is_type_diagnostic_item, span_lint_and_help};
   2 use rustc_hir as hir;
   3 use rustc_lint::LateContext;
   4 use rustc_span::sym;
   5
   6 use super::EXPECT_USED;
   7
   8 /// lint use of `expect()` for `Option`s and `Result`s
   9 pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, expect_args: &[hir::Expr<'_>]) {
  10     let obj_ty = cx.typeck_results().expr_ty(&expect_args[0]).peel_refs();
  11
  12     let mess = if is_type_diagnostic_item(cx, obj_ty, sym::option_type) {
  13         Some((EXPECT_USED, "an Option", "None"))
  14     } else if is_type_diagnostic_item(cx, obj_ty, sym::result_type) {
  15         Some((EXPECT_USED, "a Result", "Err"))
  16     } else {
  17         None
  18     };
  19
  20     if let Some((lint, kind, none_value)) = mess {
  21         span_lint_and_help(
  22             cx,
  23             lint,
  24             expr.span,
  25             &format!("used `expect()` on `{}` value", kind,),
  26             None,
  27             &format!("if this value is an `{}`, it will panic", none_value,),
  28         );
  29     }
  30 }