bug#64198: Feature request: compile.el's "Find this in" prompt should be hookable.

[Dave Abrahams]

> On Jun 22, 2023, at 10:02 AM, Eli Zaretskii <eliz@gnu.org> wrote:
> 
>> From: Dave Abrahams <dave@boostpro.com>
>> Date: Wed, 21 Jun 2023 09:09:08 -0700
>> Cc: 64198@debbugs.gnu.org
>> 
>> Before discussing patches, could you please describe your situation?
>> Specifically, how does it happen that neither the compilation
>> directory plus the file name shown by the diagnostics nor the search
>> of compilation-search-path succeed to locate the file?  And what would
>> the hook function you suggest adding do to resolve this, i.e. how
>> would it know where to look for the file?
>> 
>> When Swift asserts, it doesn't write the path to the file into the output, 
>> because… reasons I grudgingly
>> accept.  So one needs to guess at the file.  
>> https://github.com/apple/swift/issues/66777 contains all the
>> details, but if you want additional info, please ask.
> 
> I don't know what Swift is, and that issue talks about something
> called #fileID, which I again have no idea about.  So yes, please do
> elaborate, and TIA.

Swift is a programming language.  When its assertions (like C's assert() macro) 
fail, a diagnostic is output with a file ID and line. The file ID looks like a 
path, but it's really not. If it's a path in the filesystem, that's 
coincidental but it's likely to point to the right file.  I don't want to 
manually hunt down the file every time an assertion fails; I'd rather emacs 
made an educated guess based on the current project.  It's obviously not the 
right answer for everyone, but I'd like to have the hooks needed to implement 
that without too much hackery.