diff options
| -rw-r--r-- | clippy_lints/src/strings.rs | 90 |
1 files changed, 74 insertions, 16 deletions
diff --git a/clippy_lints/src/strings.rs b/clippy_lints/src/strings.rs index 4a5f143a2d3..6762fc71d45 100644 --- a/clippy_lints/src/strings.rs +++ b/clippy_lints/src/strings.rs @@ -1,4 +1,4 @@ -use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg, span_lint_and_then}; +use clippy_utils::diagnostics::{span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then}; use clippy_utils::source::{snippet, snippet_with_applicability}; use clippy_utils::ty::is_type_lang_item; use clippy_utils::{ @@ -438,27 +438,85 @@ declare_clippy_lint! { declare_lint_pass!(StringToString => [STRING_TO_STRING]); +fn is_parent_map_like(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<rustc_span::Span> { + if let Some(parent_expr) = get_parent_expr(cx, expr) + && let ExprKind::MethodCall(name, ..) = parent_expr.kind + && name.ident.name == sym::map + && let Some(caller_def_id) = cx.typeck_results().type_dependent_def_id(parent_expr.hir_id) + && (clippy_utils::is_diag_item_method(cx, caller_def_id, sym::Result) + || clippy_utils::is_diag_item_method(cx, caller_def_id, sym::Option) + || clippy_utils::is_diag_trait_item(cx, caller_def_id, sym::Iterator)) + { + Some(parent_expr.span) + } else { + None + } +} + +fn is_called_from_map_like(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<rustc_span::Span> { + let parent = get_parent_expr(cx, expr)?; + + if matches!(parent.kind, ExprKind::Closure(_)) { + is_parent_map_like(cx, parent) + } else { + None + } +} + +fn suggest_cloned_string_to_string(cx: &LateContext<'_>, span: rustc_span::Span) { + span_lint_and_help( + cx, + STRING_TO_STRING, + span, + "`to_string()` called on a `String`", + None, + "consider using `.cloned()`", + ); +} + impl<'tcx> LateLintPass<'tcx> for StringToString { fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'_>) { if expr.span.from_expansion() { return; } - if let ExprKind::MethodCall(path, self_arg, [], _) = &expr.kind - && path.ident.name == sym::to_string - && let ty = cx.typeck_results().expr_ty(self_arg) - && is_type_lang_item(cx, ty, LangItem::String) - { - #[expect(clippy::collapsible_span_lint_calls, reason = "rust-clippy#7797")] - span_lint_and_then( - cx, - STRING_TO_STRING, - expr.span, - "`to_string()` called on a `String`", - |diag| { - diag.help("consider using `.clone()`"); - }, - ); + match &expr.kind { + ExprKind::MethodCall(path, self_arg, [], _) => { + if path.ident.name == sym::to_string + && let ty = cx.typeck_results().expr_ty(self_arg) + && is_type_lang_item(cx, ty.peel_refs(), LangItem::String) + { + if let Some(parent_span) = is_called_from_map_like(cx, expr) { + suggest_cloned_string_to_string(cx, parent_span); + } else { + #[expect(clippy::collapsible_span_lint_calls, reason = "rust-clippy#7797")] + span_lint_and_then( + cx, + STRING_TO_STRING, + expr.span, + "`to_string()` called on a `String`", + |diag| { + diag.help("consider using `.clone()`"); + }, + ); + } + } + }, + ExprKind::Path(QPath::TypeRelative(ty, segment)) => { + if segment.ident.name == sym::to_string + && let rustc_hir::TyKind::Path(QPath::Resolved(_, path)) = ty.peel_refs().kind + && let rustc_hir::def::Res::Def(_, def_id) = path.res + && cx + .tcx + .lang_items() + .get(LangItem::String) + .is_some_and(|lang_id| lang_id == def_id) + && let Some(parent_span) = is_parent_map_like(cx, expr) + { + suggest_cloned_string_to_string(cx, parent_span); + } + }, + _ => {}, } } } |