Add help for matches for if let in arm guard

rust-lang · Mar 7, 2021 · 63fb294 · 63fb294
1 parent 23bcea4
commit 63fb294
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Showing 2 changed files with 7 additions and 1 deletion.
diff --git 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
@@ -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