error: Undefined Behavior: writing to ALLOC which is read-only
  --> $DIR/mkstemp_immutable_arg.rs:LL:CC
   |
LL |     let _fd = unsafe { libc::mkstemp(s) };
   |                        ^^^^^^^^^^^^^^^^ writing to ALLOC which is read-only
   |
   = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
   = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
   = note: backtrace:
   = note: inside `test_mkstemp_immutable_arg` at $DIR/mkstemp_immutable_arg.rs:LL:CC
note: inside `main` at $DIR/mkstemp_immutable_arg.rs:LL:CC
  --> $DIR/mkstemp_immutable_arg.rs:LL:CC
   |
LL |     test_mkstemp_immutable_arg();
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace

error: aborting due to previous error