LLVM is inconsistent about how it converts `errno` to `std::error_code`.
This can cause problems because values outside of `std::errc` compare
differently if one is system and one is generic on POSIX systems.
This is even more of a problem on Windows where use of the system
category is just wrong, as that is for Windows errors, which have a
completely different mapping than POSIX/generic errors. This patch fixes
one instance of this mistake in `JSONTransport.cpp`.
This patch adds `errnoAsErrorCode()` which makes it so people do not
need to think about this issue in the future. It also cleans up a lot of
usage of `errno` in LLVM and Clang.
This patch adds the basic functions needed for controlling auto conversion on z/OS.
Auto conversion is enabled on untagged input file to ASCII by making the assumption that all untagged files are EBCDIC encoded. Output files are auto converted to EBCDIC IBM-1047.
This change also enables conversion for stdin/stdout/stderr.
For more information on how fcntl controls codepage https://www.ibm.com/docs/en/zos/2.4.0?topic=descriptions-fcntl-bpx1fct-bpx4fct-control-open-file-descriptors
Reviewed By: anirudhp
Differential Revision: https://reviews.llvm.org/D100483
