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use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::{path_to_local_id, peel_blocks, strip_pat_refs};
use rustc_errors::Applicability;
use rustc_hir::{ByRef, ExprKind, Local, MatchSource, PatKind, QPath};
use rustc_lint::LateContext;
use super::INFALLIBLE_DESTRUCTURING_MATCH;
pub(crate) fn check(cx: &LateContext<'_>, local: &Local<'_>) -> bool {
if_chain! {
if !local.span.from_expansion();
if let Some(expr) = local.init;
if let ExprKind::Match(target, arms, MatchSource::Normal) = expr.kind;
if arms.len() == 1 && arms[0].guard.is_none();
if let PatKind::TupleStruct(
QPath::Resolved(None, variant_name), args, _) = arms[0].pat.kind;
if args.len() == 1;
if let PatKind::Binding(binding, arg, ..) = strip_pat_refs(&args[0]).kind;
let body = peel_blocks(arms[0].body);
if path_to_local_id(body, arg);
then {
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
INFALLIBLE_DESTRUCTURING_MATCH,
local.span,
"you seem to be trying to use `match` to destructure a single infallible pattern. \
Consider using `let`",
"try this",
format!(
"let {}({}{}) = {};",
snippet_with_applicability(cx, variant_name.span, "..", &mut applicability),
if binding.0 == ByRef::Yes { "ref " } else { "" },
snippet_with_applicability(cx, local.pat.span, "..", &mut applicability),
snippet_with_applicability(cx, target.span, "..", &mut applicability),
),
applicability,
);
return true;
}
}
false
}
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