Simplify panic_if_treat_err_as_bug avoiding allocations

Author: zzau13

compiler/rustc_errors/src/lib.rs

@@ -973,16 +973,14 @@ impl HandlerInner {
 
     fn panic_if_treat_err_as_bug(&self) {
         if self.treat_err_as_bug() {
-            let s = match (self.err_count(), self.flags.treat_err_as_bug.unwrap_or(0)) {
-                (0, _) => return,
-                (1, 1) => "aborting due to `-Z treat-err-as-bug=1`".to_string(),
-                (1, _) => return,
-                (count, as_bug) => format!(
+            match (self.err_count(), self.flags.treat_err_as_bug.unwrap_or(0)) {
+                (1, 1) => panic!("aborting due to `-Z treat-err-as-bug=1`"),
+                (0, _) | (1, _) => {}
+                (count, as_bug) => panic!(
                     "aborting after {} errors due to `-Z treat-err-as-bug={}`",
                     count, as_bug,
                 ),
-            };
-            panic!(s);
+            }
         }
     }
 }