error: using `libc::strlen` on a `CString` or `CStr` value
  --> $DIR/strlen_on_c_strings.rs:11:24
   |
LL |     let len = unsafe { libc::strlen(cstring.as_ptr()) };
   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `-D clippy::strlen-on-c-strings` implied by `-D warnings`
help: try this (you might also need to get rid of `unsafe` block in some cases):
   |
LL |     let len = unsafe { cstring.as_bytes().len() };
   |                        ~~~~~~~~~~~~~~~~~~~~~~~~

error: using `libc::strlen` on a `CString` or `CStr` value
  --> $DIR/strlen_on_c_strings.rs:15:24
   |
LL |     let len = unsafe { libc::strlen(cstr.as_ptr()) };
   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
help: try this (you might also need to get rid of `unsafe` block in some cases):
   |
LL |     let len = unsafe { cstr.to_bytes().len() };
   |                        ~~~~~~~~~~~~~~~~~~~~~

error: aborting due to 2 previous errors