src/tools/clippy/clippy_lints/src/functions/impl_trait_in_params.rs

   1 use clippy_utils::{diagnostics::span_lint_and_then, is_in_test_function};
   2
   3 use rustc_hir::{intravisit::FnKind, Body, HirId};
   4 use rustc_lint::LateContext;
   5 use rustc_span::Span;
   6
   7 use super::IMPL_TRAIT_IN_PARAMS;
   8
   9 pub(super) fn check_fn<'tcx>(cx: &LateContext<'_>, kind: &'tcx FnKind<'_>, body: &'tcx Body<'_>, hir_id: HirId) {
  10     if cx.tcx.visibility(cx.tcx.hir().body_owner_def_id(body.id())).is_public() && !is_in_test_function(cx.tcx, hir_id)
  11     {
  12         if let FnKind::ItemFn(ident, generics, _) = kind {
  13             for param in generics.params {
  14                 if param.is_impl_trait() {
  15                     // No generics with nested generics, and no generics like FnMut(x)
  16                     span_lint_and_then(
  17                         cx,
  18                         IMPL_TRAIT_IN_PARAMS,
  19                         param.span,
  20                         "'`impl Trait` used as a function parameter'",
  21                         |diag| {
  22                             if let Some(gen_span) = generics.span_for_param_suggestion() {
  23                                 diag.span_suggestion_with_style(
  24                                     gen_span,
  25                                     "add a type paremeter",
  26                                     format!(", {{ /* Generic name */ }}: {}", &param.name.ident().as_str()[5..]),
  27                                     rustc_errors::Applicability::HasPlaceholders,
  28                                     rustc_errors::SuggestionStyle::ShowAlways,
  29                                 );
  30                             } else {
  31                                 diag.span_suggestion_with_style(
  32                                     Span::new(
  33                                         body.params[0].span.lo() - rustc_span::BytePos(1),
  34                                         ident.span.hi(),
  35                                         ident.span.ctxt(),
  36                                         ident.span.parent(),
  37                                     ),
  38                                     "add a type paremeter",
  39                                     format!("<{{ /* Generic name */ }}: {}>", &param.name.ident().as_str()[5..]),
  40                                     rustc_errors::Applicability::HasPlaceholders,
  41                                     rustc_errors::SuggestionStyle::ShowAlways,
  42                                 );
  43                             }
  44                         },
  45                     );
  46                 }
  47             }
  48         }
  49     }
  50 }