Create ui test for -Ztreat-err-as-bug err

Author: spastorino

src/test/ui/treat-err-as-bug/err.rs

@@ -0,0 +1,11 @@
+// compile-flags: -Ztreat-err-as-bug
+// failure-status: 101
+// error-pattern: aborting due to `-Z treat-err-as-bug=1`
+// error-pattern: [eval_to_allocation_raw] const-evaluating + checking `C`
+// normalize-stderr-test "note: .*\n\n" -> ""
+// normalize-stderr-test "thread 'rustc' panicked.*\n" -> ""
+
+#![crate_type = "rlib"]
+
+pub static C: u32 = 0 - 1;
+//~^ ERROR could not evaluate static initializer

src/test/ui/treat-err-as-bug/err.stderr

@@ -0,0 +1,12 @@
+error[E0080]: could not evaluate static initializer
+  --> $DIR/err.rs:10:21
+   |
+LL | pub static C: u32 = 0 - 1;
+   |                     ^^^^^ attempt to compute `0_u32 - 1_u32`, which would overflow
+
+error: internal compiler error: unexpected panic
+
+query stack during panic:
+#0 [eval_to_allocation_raw] const-evaluating + checking `C`
+#1 [eval_to_allocation_raw] const-evaluating + checking `C`
+end of query stack