54 lines
1.9 KiB
Rust
54 lines
1.9 KiB
Rust
use crate::utils::{eager_or_lazy, usage};
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use crate::utils::{is_type_diagnostic_item, snippet, span_lint_and_sugg};
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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 super::UNNECESSARY_LAZY_EVALUATIONS;
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/// lint use of `<fn>_else(simple closure)` for `Option`s and `Result`s that can be
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/// replaced with `<fn>(return value of simple closure)`
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pub(super) fn lint<'tcx>(
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cx: &LateContext<'tcx>,
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expr: &'tcx hir::Expr<'_>,
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args: &'tcx [hir::Expr<'_>],
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simplify_using: &str,
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) {
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let is_option = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&args[0]), sym!(option_type));
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let is_result = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&args[0]), sym!(result_type));
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if is_option || is_result {
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if let hir::ExprKind::Closure(_, _, eid, _, _) = args[1].kind {
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let body = cx.tcx.hir().body(eid);
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let body_expr = &body.value;
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if usage::BindingUsageFinder::are_params_used(cx, body) {
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return;
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}
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if eager_or_lazy::is_eagerness_candidate(cx, body_expr) {
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let msg = if is_option {
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"unnecessary closure used to substitute value for `Option::None`"
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} else {
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"unnecessary closure used to substitute value for `Result::Err`"
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};
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span_lint_and_sugg(
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cx,
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UNNECESSARY_LAZY_EVALUATIONS,
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expr.span,
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msg,
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&format!("Use `{}` instead", simplify_using),
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format!(
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"{0}.{1}({2})",
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snippet(cx, args[0].span, ".."),
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simplify_using,
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snippet(cx, body_expr.span, ".."),
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),
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Applicability::MachineApplicable,
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);
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}
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}
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}
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}
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