91 lines
3.4 KiB
Rust
91 lines
3.4 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::higher;
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use clippy_utils::method_chain_args;
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use clippy_utils::source::snippet_with_applicability;
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use clippy_utils::ty::is_type_diagnostic_item;
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use if_chain::if_chain;
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use rustc_errors::Applicability;
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use rustc_hir::{Expr, ExprKind, PatKind, QPath};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::sym;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for unnecessary `ok()` in `while let`.
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///
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/// ### Why is this bad?
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/// Calling `ok()` in `while let` is unnecessary, instead match
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/// on `Ok(pat)`
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///
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/// ### Example
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/// ```ignore
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/// while let Some(value) = iter.next().ok() {
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/// vec.push(value)
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/// }
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///
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/// if let Some(valie) = iter.next().ok() {
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/// vec.push(value)
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/// }
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/// ```
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/// Use instead:
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/// ```ignore
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/// while let Ok(value) = iter.next() {
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/// vec.push(value)
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/// }
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///
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/// if let Ok(value) = iter.next() {
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/// vec.push(value)
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/// }
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/// ```
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#[clippy::version = "1.57.0"]
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pub MATCH_RESULT_OK,
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style,
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"usage of `ok()` in `let Some(pat)` statements is unnecessary, match on `Ok(pat)` instead"
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}
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declare_lint_pass!(MatchResultOk => [MATCH_RESULT_OK]);
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impl<'tcx> LateLintPass<'tcx> for MatchResultOk {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
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let (let_pat, let_expr, ifwhile) =
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if let Some(higher::IfLet { let_pat, let_expr, .. }) = higher::IfLet::hir(cx, expr) {
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(let_pat, let_expr, "if")
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} else if let Some(higher::WhileLet { let_pat, let_expr, .. }) = higher::WhileLet::hir(expr) {
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(let_pat, let_expr, "while")
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} else {
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return;
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};
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if_chain! {
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if let ExprKind::MethodCall(ok_path, [ref result_types_0, ..], _) = let_expr.kind; //check is expr.ok() has type Result<T,E>.ok(, _)
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if let PatKind::TupleStruct(QPath::Resolved(_, x), y, _) = let_pat.kind; //get operation
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if method_chain_args(let_expr, &["ok"]).is_some(); //test to see if using ok() methoduse std::marker::Sized;
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if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(result_types_0), sym::Result);
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if rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_path(x, false)) == "Some";
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then {
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let mut applicability = Applicability::MachineApplicable;
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let some_expr_string = snippet_with_applicability(cx, y[0].span, "", &mut applicability);
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let trimmed_ok = snippet_with_applicability(cx, let_expr.span.until(ok_path.ident.span), "", &mut applicability);
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let sugg = format!(
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"{} let Ok({}) = {}",
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ifwhile,
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some_expr_string,
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trimmed_ok.trim().trim_end_matches('.'),
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);
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span_lint_and_sugg(
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cx,
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MATCH_RESULT_OK,
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expr.span.with_hi(let_expr.span.hi()),
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"matching on `Some` with `ok()` is redundant",
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&format!("consider matching on `Ok({})` and removing the call to `ok` instead", some_expr_string),
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sugg,
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applicability,
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);
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}
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}
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}
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}
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