| 1 | use clippy_utils::diagnostics::span_lint_and_then; |
|---|---|
| 2 | use clippy_utils::ty::is_type_diagnostic_item; |
| 3 | use rustc_hir::{CaptureBy, Closure, Expr, ExprKind, PatKind}; |
| 4 | use rustc_lint::LateContext; |
| 5 | use rustc_span::sym; |
| 6 | |
| 7 | use super::MAP_ERR_IGNORE; |
| 8 | |
| 9 | pub(super) fn check(cx: &LateContext<'_>, e: &Expr<'_>, arg: &Expr<'_>) { |
| 10 | if let Some(method_id) = cx.typeck_results().type_dependent_def_id(e.hir_id) |
| 11 | && let Some(impl_id) = cx.tcx.impl_of_method(method_id) |
| 12 | && is_type_diagnostic_item(cx, cx.tcx.type_of(impl_id).instantiate_identity(), sym::Result) |
| 13 | && let ExprKind::Closure(&Closure { |
| 14 | capture_clause: CaptureBy::Ref, |
| 15 | body, |
| 16 | fn_decl_span, |
| 17 | .. |
| 18 | }) = arg.kind |
| 19 | && let closure_body = cx.tcx.hir_body(body) |
| 20 | && let [param] = closure_body.params |
| 21 | && let PatKind::Wild = param.pat.kind |
| 22 | { |
| 23 | // span the area of the closure capture and warn that the |
| 24 | // original error will be thrown away |
| 25 | #[expect(clippy::collapsible_span_lint_calls, reason = "rust-clippy#7797")] |
| 26 | span_lint_and_then( |
| 27 | cx, |
| 28 | MAP_ERR_IGNORE, |
| 29 | fn_decl_span, |
| 30 | "`map_err(|_|...` wildcard pattern discards the original error", |
| 31 | |diag| { |
| 32 | diag.help( |
| 33 | "consider storing the original error as a source in the new error, or silence this warning using an ignored identifier (`.map_err(|_foo| ...`)", |
| 34 | ); |
| 35 | }, |
| 36 | ); |
| 37 | } |
| 38 | } |
| 39 |
Definitions
Learn Rust with the experts
Find out more