From 63fb294a7455b76ecfbef6831410e5362ee9d514 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Sun, 7 Mar 2021 14:44:21 -0800
Subject: [PATCH] Add help for `matches` for `if let` in arm guard
---
compiler/rustc_ast_passes/src/feature_gate.rs | 6 +++++-
src/test/ui/rfc-2294-if-let-guard/feature-gate.stderr | 2 ++
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/compiler/rustc_ast_passes/src/feature_gate.rs b/compiler/rustc_ast_passes/src/feature_gate.rs
index e13e9bdf96b..053fa5b7897 100644
--- a/compiler/rustc_ast_passes/src/feature_gate.rs
+++ b/compiler/rustc_ast_passes/src/feature_gate.rs
@@ -638,7 +638,11 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) {
}
};
}
- gate_all!(if_let_guard, "`if let` guards are experimental");
+ gate_all!(
+ if_let_guard,
+ "`if let` guards are experimental",
+ "you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`"
+ );
gate_all!(
let_chains,
"`let` expressions in this position are experimental",
diff --git a/src/test/ui/rfc-2294-if-let-guard/feature-gate.stderr b/src/test/ui/rfc-2294-if-let-guard/feature-gate.stderr
index 2b71026dc4b..00811fe3044 100644
--- a/src/test/ui/rfc-2294-if-let-guard/feature-gate.stderr
+++ b/src/test/ui/rfc-2294-if-let-guard/feature-gate.stderr
@@ -15,6 +15,7 @@ LL | () if let 0 = 1 => {}
|
= note: see issue #51114 <https://github.com/rust-lang/rust/issues/51114> for more information
= help: add `#![feature(if_let_guard)]` to the crate attributes to enable
+ = help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`
error[E0658]: `if let` guards are experimental
--> $DIR/feature-gate.rs:76:12
@@ -24,6 +25,7 @@ LL | () if let 0 = 1 => {}
|
= note: see issue #51114 <https://github.com/rust-lang/rust/issues/51114> for more information
= help: add `#![feature(if_let_guard)]` to the crate attributes to enable
+ = help: you can write `if matches!(<expr>, <pattern>)` instead of `if let <pattern> = <expr>`
error[E0658]: `let` expressions in this position are experimental
--> $DIR/feature-gate.rs:10:16