On Fri, Dec 21, 2018 at 12:52:04PM +0100, Johannes Schindelin wrote:
> ... and in Git for Windows' Bash, it would result in something like:
> 
> 	$ git -P diff --no-index <(printf "a\nb\n") <(printf "a\nc\n")
> 	error: Could not access '/proc/24012/fd/63'
> 
> ... because the Bash is "MSYS2-aware" and knows about `/proc/` while
> `git.exe` is a pure Win32 executable that has no idea what Bash is talking
> about.
> 
> Sadly, your patch does not change the situation one bit (because it does
> not change the fact that the MSYS2 Bash passes a path to `git.exe` that is
> not a valid Windows path, and neither could it, but that's not the problem
> of your patch).

That tells me that I need to exclude Windows (excepting Cygwin) if I add
a PROCESS_SUBSTITUTION test like Ævar suggested, and that indeed is
helpful information. I'm sorry my patch won't be useful on Windows,
though.
-- 
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204