Use ui test syntax that does not interfere with rustfmt

Author: dtolnay

test_suite/tests/ui/conflict/alias-enum.rs

@@ -71,5 +71,5 @@ enum E3 {
 }
 
 fn main() {
-    @//fail
+    __FAIL__;
 }

test_suite/tests/ui/conflict/alias-enum.stderr

@@ -1,8 +1,8 @@
-error: expected expression, found `@`
+error[E0425]: cannot find value `__FAIL__` in this scope
   --> tests/ui/conflict/alias-enum.rs:74:5
    |
-74 |     @//fail
-   |     ^ expected expression
+74 |     __FAIL__;
+   |     ^^^^^^^^ not found in this scope
 
 warning: unreachable pattern
   --> tests/ui/conflict/alias-enum.rs:13:9

test_suite/tests/ui/conflict/alias.rs

@@ -35,5 +35,5 @@ struct S3 {
 }
 
 fn main() {
-    @//fail
+    __FAIL__;
 }

test_suite/tests/ui/conflict/alias.stderr

@@ -1,8 +1,8 @@
-error: expected expression, found `@`
+error[E0425]: cannot find value `__FAIL__` in this scope
   --> tests/ui/conflict/alias.rs:38:5
    |
-38 |     @//fail
-   |     ^ expected expression
+38 |     __FAIL__;
+   |     ^^^^^^^^ not found in this scope
 
 warning: unreachable pattern
   --> tests/ui/conflict/alias.rs:10:5