48 lines
1.6 KiB
Rust
48 lines
1.6 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::ty::is_type_diagnostic_item;
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use clippy_utils::{is_expr_untyped_identity_function, is_trait_method, path_to_local};
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use rustc_ast::BindingMode;
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use rustc_errors::Applicability;
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use rustc_hir::{self as hir, Node, PatKind};
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use rustc_lint::LateContext;
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use rustc_span::{Span, sym};
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use super::MAP_IDENTITY;
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pub(super) fn check(
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cx: &LateContext<'_>,
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expr: &hir::Expr<'_>,
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caller: &hir::Expr<'_>,
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map_arg: &hir::Expr<'_>,
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name: &str,
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_map_span: Span,
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) {
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let caller_ty = cx.typeck_results().expr_ty(caller);
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if (is_trait_method(cx, expr, sym::Iterator)
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|| is_type_diagnostic_item(cx, caller_ty, sym::Result)
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|| is_type_diagnostic_item(cx, caller_ty, sym::Option))
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&& is_expr_untyped_identity_function(cx, map_arg)
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&& let Some(sugg_span) = expr.span.trim_start(caller.span)
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{
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// If the result of `.map(identity)` is used as a mutable reference,
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// the caller must not be an immutable binding.
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if cx.typeck_results().expr_ty_adjusted(expr).is_mutable_ptr()
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&& let Some(hir_id) = path_to_local(caller)
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&& let Node::Pat(pat) = cx.tcx.hir_node(hir_id)
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&& !matches!(pat.kind, PatKind::Binding(BindingMode::MUT, ..))
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{
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return;
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}
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span_lint_and_sugg(
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cx,
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MAP_IDENTITY,
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sugg_span,
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"unnecessary map of the identity function",
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format!("remove the call to `{name}`"),
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String::new(),
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Applicability::MachineApplicable,
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);
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}
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}
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