Update UI tests

src/test/ui/inference/char-as-str-single.fixed

@@ -8,4 +8,5 @@
 fn main() {
     let _: char = 'a'; //~ ERROR mismatched types
     let _: char = '人'; //~ ERROR mismatched types
+    let _: char = '\''; //~ ERROR mismatched types
 }

src/test/ui/inference/char-as-str-single.rs

@@ -8,4 +8,5 @@
 fn main() {
     let _: char = "a"; //~ ERROR mismatched types
     let _: char = "人"; //~ ERROR mismatched types
+    let _: char = "'"; //~ ERROR mismatched types
 }

src/test/ui/inference/char-as-str-single.stderr

@@ -24,6 +24,19 @@ help: if you meant to write a `char` literal, use single quotes
 LL |     let _: char = '人';
    |                   ~~~~
 
-error: aborting due to 2 previous errors
+error[E0308]: mismatched types
+  --> $DIR/char-as-str-single.rs:11:19
+   |
+LL |     let _: char = "'";
+   |            ----   ^^^ expected `char`, found `&str`
+   |            |
+   |            expected due to this
+   |
+help: if you meant to write a `char` literal, use single quotes
+   |
+LL |     let _: char = '\'';
+   |                   ~~~~
+
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0308`.

src/test/ui/inference/str-as-char.fixed

@@ -4,5 +4,7 @@
 // run-rustfix
 
 fn main() {
-    let _: &str = "a"; //~ ERROR mismatched types
+    let _: &str = "a";   //~ ERROR mismatched types
+    let _: &str = "\"\"\""; //~ ERROR character literal may only contain one codepoint
+    let _: &str = "\"\"\""; //~ ERROR character literal may only contain one codepoint
 }

src/test/ui/inference/str-as-char.rs

@@ -4,5 +4,7 @@
 // run-rustfix
 
 fn main() {
-    let _: &str = 'a'; //~ ERROR mismatched types
+    let _: &str = 'a';   //~ ERROR mismatched types
+    let _: &str = '"""'; //~ ERROR character literal may only contain one codepoint
+    let _: &str = '\"\"\"'; //~ ERROR character literal may only contain one codepoint
 }

src/test/ui/inference/str-as-char.stderr

@@ -1,3 +1,25 @@
+error: character literal may only contain one codepoint
+  --> $DIR/str-as-char.rs:8:19
+   |
+LL |     let _: &str = '"""';
+   |                   ^^^^^
+   |
+help: if you meant to write a `str` literal, use double quotes
+   |
+LL |     let _: &str = "\"\"\"";
+   |                   ~~~~~~~~
+
+error: character literal may only contain one codepoint
+  --> $DIR/str-as-char.rs:9:19
+   |
+LL |     let _: &str = '\"\"\"';
+   |                   ^^^^^^^^
+   |
+help: if you meant to write a `str` literal, use double quotes
+   |
+LL |     let _: &str = "\"\"\"";
+   |                   ~~~~~~~~
+
 error[E0308]: mismatched types
   --> $DIR/str-as-char.rs:7:19
    |
@@ -11,6 +33,6 @@ help: if you meant to write a `str` literal, use double quotes
 LL |     let _: &str = "a";
    |                   ~~~
 
-error: aborting due to previous error
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0308`.