add testcase

Author: woruyu

clang/test/Driver/fsanitize-ignorelist.c

@@ -71,3 +71,10 @@
 // CHECK-MISSING-CFI-NO-IGNORELIST-NOT: error: no such file or directory: '{{.*}}cfi_ignorelist.txt'
 
 // DELIMITERS: {{^ *"}}
+
+// Check that a missing file passed to -fsanitize-system-ignorelist triggers a clean error without crashing.
+// RUN: not %clang --target=x86_64-linux-gnu  -Xclang -fsanitize-system-ignorelist=%t.nonexistent %s  -c -o /dev/null 2>&1 | FileCheck %s --check-prefix=CHECK-SYSTEM-IGNORELIST-NOFILE
+// CHECK-SYSTEM-IGNORELIST-NOFILE: error: failed to load NoSanitize file: can't open file '{{.*}}.nonexistent': No such file or directory
+// CHECK-SYSTEM-IGNORELIST-NOFILE-NOT: Stack dump:
+// CHECK-SYSTEM-IGNORELIST-NOFILE-NOT: PLEASE submit a bug report
+// CHECK-SYSTEM-IGNORELIST-NOFILE-NOT: diagnostic msg: