90 lines
3.4 KiB
Rust
90 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::is_res_lang_ctor;
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use clippy_utils::source::snippet_with_context;
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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, LangItem, PatKind};
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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(value) = 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, recv, [], ..) = let_expr.kind; //check is expr.ok() has type Result<T,E>.ok(, _)
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if let PatKind::TupleStruct(ref pat_path, [ok_pat], _) = let_pat.kind; //get operation
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if ok_path.ident.as_str() == "ok";
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if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(recv), sym::Result);
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if is_res_lang_ctor(cx, cx.qpath_res(pat_path, let_pat.hir_id), LangItem::OptionSome);
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let ctxt = expr.span.ctxt();
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if let_expr.span.ctxt() == ctxt;
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if let_pat.span.ctxt() == ctxt;
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then {
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let mut applicability = Applicability::MachineApplicable;
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let some_expr_string = snippet_with_context(cx, ok_pat.span, ctxt, "", &mut applicability).0;
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let trimmed_ok = snippet_with_context(cx, recv.span, ctxt, "", &mut applicability).0;
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let sugg = format!(
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"{ifwhile} let Ok({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({some_expr_string})` and removing the call to `ok` instead"),
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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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