Function rs_roundtrip_ix_substring

crates/ffi/src/ix/data.rs:393–398

(
  sub_ptr: LeanIxSubstring<LeanBorrowed<'_>>,
)

#[cfg(feature = "test-ffi")]
#[unsafe(no_mangle)]
pub extern "C" fn rs_roundtrip_ix_substring(
  sub_ptr: LeanIxSubstring<LeanBorrowed<'_>>,
) -> LeanIxSubstring<LeanOwned> {
  let sub = sub_ptr.decode();
  LeanIxSubstring::build(&sub)
}

/// Round-trip an Ix.SourceInfo: decode from Lean, re-encode.
#[cfg(feature = "test-ffi")]