fix type suggestions in match arms

tests/ui/inference/char-as-str-single.fixed

@@ -10,3 +10,12 @@ fn main() {
     let _: char = '人'; //~ ERROR mismatched types
     let _: char = '\''; //~ ERROR mismatched types
 }
+
+// regression test for https://github.com/rust-lang/rust/issues/109586
+#[allow(dead_code)]
+fn convert_c_to_str(c: char) {
+    match c {
+        'A' => {} //~ ERROR mismatched types
+        _ => {}
+    }
+}

tests/ui/inference/char-as-str-single.rs

@@ -10,3 +10,12 @@ fn main() {
     let _: char = "人"; //~ ERROR mismatched types
     let _: char = "'"; //~ ERROR mismatched types
 }
+
+// regression test for https://github.com/rust-lang/rust/issues/109586
+#[allow(dead_code)]
+fn convert_c_to_str(c: char) {
+    match c {
+        "A" => {} //~ ERROR mismatched types
+        _ => {}
+    }
+}

tests/ui/inference/char-as-str-single.stderr

@@ -37,6 +37,19 @@ help: if you meant to write a `char` literal, use single quotes
 LL |     let _: char = '\'';
    |                   ~~~~
 
-error: aborting due to 3 previous errors
+error[E0308]: mismatched types
+  --> $DIR/char-as-str-single.rs:18:9
+   |
+LL |     match c {
+   |           - this expression has type `char`
+LL |         "A" => {}
+   |         ^^^ expected `char`, found `&str`
+   |
+help: if you meant to write a `char` literal, use single quotes
+   |
+LL |         'A' => {}
+   |         ~~~
+
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0308`.