From 5dcfdbf31e06db2f579f665195cb9471c3d4a629 Mon Sep 17 00:00:00 2001
From: Maybe Waffle <waffle.lapkin@gmail.com>
Date: Sun, 24 Jul 2022 21:16:44 +0400
Subject: [PATCH] `for_loop_over_fallibles`: suggest `while let` loop

---
 compiler/rustc_lint/src/for_loop_over_fallibles.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/compiler/rustc_lint/src/for_loop_over_fallibles.rs b/compiler/rustc_lint/src/for_loop_over_fallibles.rs
index 78b6ca6a653..1a618882781 100644
--- a/compiler/rustc_lint/src/for_loop_over_fallibles.rs
+++ b/compiler/rustc_lint/src/for_loop_over_fallibles.rs
@@ -84,6 +84,16 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
                     "",
                     Applicability::MaybeIncorrect
                 );
+            } else {
+                warn.multipart_suggestion_verbose(
+                    format!("to check pattern in a loop use `while let`"),
+                    vec![
+                        // NB can't use `until` here because `expr.span` and `pat.span` have different syntax contexts
+                        (expr.span.with_hi(pat.span.lo()), format!("while let {var}(")),
+                        (pat.span.between(arg.span), format!(") = ")),
+                    ],
+                    Applicability::MaybeIncorrect
+                );
             }
 
             warn.multipart_suggestion_verbose(