builtin_macros: Add test for file!()

Author: CohenArthur

gcc/testsuite/rust/execute/torture/builtin_macros1.rs

@@ -0,0 +1,18 @@
+// { dg-output "rust/execute/torture/builtin_macros1.rs" }
+macro_rules! file {
+    () => {{}};
+}
+
+extern "C" {
+    fn printf(fmt: *const i8, ...);
+}
+
+fn print(s: &str) {
+    printf("%s\n\0" as *const str as *const i8, s);
+}
+
+fn main() -> i32 {
+    print(file!());
+
+    0
+}