58 lines
2.6 KiB
Rust
58 lines
2.6 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::source::snippet_with_context;
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use clippy_utils::ty::implements_trait;
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use clippy_utils::{is_diag_item_method, is_diag_trait_item, peel_middle_ty_refs, sym};
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use rustc_errors::Applicability;
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use rustc_hir as hir;
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use rustc_lint::LateContext;
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use rustc_span::Symbol;
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use super::IMPLICIT_CLONE;
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pub fn check(cx: &LateContext<'_>, method_name: Symbol, expr: &hir::Expr<'_>, recv: &hir::Expr<'_>) {
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if let Some(method_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id)
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&& is_clone_like(cx, method_name, method_def_id)
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&& let return_type = cx.typeck_results().expr_ty(expr)
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&& let input_type = cx.typeck_results().expr_ty(recv)
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&& let (input_type, ref_count) = peel_middle_ty_refs(input_type)
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&& !(ref_count > 0 && is_diag_trait_item(cx, method_def_id, sym::ToOwned))
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&& let Some(ty_name) = input_type.ty_adt_def().map(|adt_def| cx.tcx.item_name(adt_def.did()))
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&& return_type == input_type
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&& let Some(clone_trait) = cx.tcx.lang_items().clone_trait()
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&& implements_trait(cx, return_type, clone_trait, &[])
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{
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let mut app = Applicability::MachineApplicable;
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let recv_snip = snippet_with_context(cx, recv.span, expr.span.ctxt(), "..", &mut app).0;
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span_lint_and_sugg(
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cx,
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IMPLICIT_CLONE,
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expr.span,
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format!("implicitly cloning a `{ty_name}` by calling `{method_name}` on its dereferenced type"),
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"consider using",
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if ref_count > 1 {
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format!("({}{recv_snip}).clone()", "*".repeat(ref_count - 1))
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} else {
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format!("{recv_snip}.clone()")
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},
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app,
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);
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}
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}
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/// Returns true if the named method can be used to clone the receiver.
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pub fn is_clone_like(cx: &LateContext<'_>, method_name: Symbol, method_def_id: hir::def_id::DefId) -> bool {
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match method_name {
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sym::to_os_string => is_diag_item_method(cx, method_def_id, sym::OsStr),
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sym::to_owned => is_diag_trait_item(cx, method_def_id, sym::ToOwned),
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sym::to_path_buf => is_diag_item_method(cx, method_def_id, sym::Path),
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sym::to_string => is_diag_trait_item(cx, method_def_id, sym::ToString),
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sym::to_vec => cx
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.tcx
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.impl_of_assoc(method_def_id)
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.filter(|&impl_did| {
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cx.tcx.type_of(impl_did).instantiate_identity().is_slice() && cx.tcx.impl_trait_ref(impl_did).is_none()
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})
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.is_some(),
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_ => false,
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}
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}
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