One more test case.

src/test/ui/loops/loop-no-implicit-break.rs

@@ -24,4 +24,8 @@ fn foo() -> i8 {
     loop {
         return 1;
     }
+
+    loop {
+        1 //~ ERROR mismatched types
+    }
 }

src/test/ui/loops/loop-no-implicit-break.stderr

@@ -31,6 +31,17 @@ help: you might have meant to return this value
 LL |         return 1;
    |         ^^^^^^  ^
 
-error: aborting due to 3 previous errors
+error[E0308]: mismatched types
+  --> $DIR/loop-no-implicit-break.rs:29:9
+   |
+LL |         1
+   |         ^ expected `()`, found integer
+   |
+help: you might have meant to return this value
+   |
+LL |         return 1;
+   |         ^^^^^^  ^
+
+error: aborting due to 4 previous errors
 
 For more information about this error, try `rustc --explain E0308`.