修复19-10代码及其编译返还信息。

listings/ch19-patterns-and-matching/listing-19-10/output.txt

@@ -1,13 +1,13 @@
 $ cargo run
    Compiling patterns v0.1.0 (file:///projects/patterns)
-warning: irrefutable `let...else` pattern
- --> src/main.rs:2:5
+warning: irrefutable `if let` pattern
+ --> src/main.rs:2:8
   |
-2 |     let x = 5 else {
-  |     ^^^^^^^^^
+2 |     if let x = 5 {
+  |        ^^^^^^^^^
   |
-  = note: this pattern will always match, so the `else` clause is useless
-  = help: consider removing the `else` clause
+  = note: this pattern will always match, so the `if let` is useless
+  = help: consider replacing the `if let` with a `let`
   = note: `#[warn(irrefutable_let_patterns)]` on by default
 
 warning: `patterns` (bin "patterns") generated 1 warning

listings/ch19-patterns-and-matching/listing-19-10/src/main.rs

@@ -1,7 +1,7 @@
 fn main() {
     // ANCHOR: here
-    if let x = 5 else {
-        return;
+    if let x = 5 {
+        println!("{x}");
     };
     // ANCHOR_END: here
 }