Eric Fiselier 9158bfd32e Implement filesystem_error::what() and improve reporting.
This patch implements the `what()` for filesystem errors. The message
includes the 'what_arg', any paths that were specified, and the
error code message.

Additionally this patch refactors how errors are created, making it easier
to report them correctly.

llvm-svn: 337664
2018-07-23 02:00:52 +00:00
..
2018-07-09 23:45:09 +00:00