llvm-c support for UnknownProvenance.
This is great that you though of updating the echo test.
The echo test is a test that read some IR, and then spit it back out, using the C API. There are some files containing LLVM IR that contain various pieces of IR that are run through he echo tool. This ensure that the IR is read and then regenerated properly through the C API.
It would be great if you could either modify an existing test or add a new one so that the unknown provenance construct is exercised by the C API - which in turn will prove that this code works as expected.