52 lines
2.4 KiB
Rust
52 lines
2.4 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_note;
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use clippy_utils::macros::{is_panic, root_macro_call};
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use clippy_utils::ty::is_type_diagnostic_item;
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use clippy_utils::visitors::is_local_used;
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use clippy_utils::{is_wild, peel_blocks_with_stmt};
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use rustc_hir::{Arm, Expr, PatKind};
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use rustc_lint::LateContext;
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use rustc_span::symbol::{kw, sym};
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use super::MATCH_WILD_ERR_ARM;
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pub(crate) fn check<'tcx>(cx: &LateContext<'tcx>, ex: &Expr<'tcx>, arms: &[Arm<'tcx>]) {
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let ex_ty = cx.typeck_results().expr_ty(ex).peel_refs();
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if is_type_diagnostic_item(cx, ex_ty, sym::Result) {
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for arm in arms {
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if let PatKind::TupleStruct(ref path, inner, _) = arm.pat.kind {
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let path_str = rustc_hir_pretty::to_string(rustc_hir_pretty::NO_ANN, |s| s.print_qpath(path, false));
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if path_str == "Err" {
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let mut matching_wild = inner.iter().any(is_wild);
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let mut ident_bind_name = kw::Underscore;
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if !matching_wild {
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// Looking for unused bindings (i.e.: `_e`)
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for pat in inner.iter() {
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if let PatKind::Binding(_, id, ident, None) = pat.kind {
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if ident.as_str().starts_with('_') && !is_local_used(cx, arm.body, id) {
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ident_bind_name = ident.name;
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matching_wild = true;
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}
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}
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}
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}
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if_chain! {
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if matching_wild;
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if let Some(macro_call) = root_macro_call(peel_blocks_with_stmt(arm.body).span);
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if is_panic(cx, macro_call.def_id);
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then {
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// `Err(_)` or `Err(_e)` arm with `panic!` found
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span_lint_and_note(cx,
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MATCH_WILD_ERR_ARM,
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arm.pat.span,
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&format!("`Err({ident_bind_name})` matches all errors"),
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None,
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"match each error separately or use the error output, or use `.expect(msg)` if the error case is unreachable",
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);
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}
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}
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}
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}
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}
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}
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}
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