Merge pull request #1185 from peter-kehl/1184

For #1184 closes #1184

Author: marioidival

src/flow_control/if_let.md

@@ -94,6 +94,26 @@ fn main() {
 }
 ```
 
+Another benefit: `if let` allows to match enum non-parameterized variants, even if the enum doesn't `#[derive(PartialEq)]`, neither we implement `PartialEq` for it. In such case, classic `if Foo::Bar==a` fails, because instances of such enum are not comparable for equality. However, `if let` works.
+
+Would you like a challenge? Fix the following example to use `if let`:
+
+```rust,editable,ignore
+// This enum purposely doesn't #[derive(PartialEq)],
+// neither we implement PartialEq for it. That's why comparing Foo::Bar==a fails below.
+enum Foo {Bar}
+
+fn main() {
+    let a = Foo::Bar;
+
+    // Variable a matches Foo::Bar
+    if Foo::Bar == a {
+    // ^-- this causes a compile-time error. Use `if let` instead.
+        println!("a is foobar");
+    }
+}
+```
+
 ### See also:
 
 [`enum`][enum], [`Option`][option], and the [RFC][if_let_rfc]