Triggering -save-temps from the front-end code

[Marc Glisse]

On Mon, 28 Nov 2022, Florian Weimer via Gcc wrote:

> * Arsen Arsenović:
>
>> Hi,
>>
>> Florian Weimer via Gcc <gcc@gcc.gnu.org> writes:
>>
>>> Unfortunately, some build systems immediately delete the input source
>>> files.  Is there some easy way I can dump the pre-processed and
>>> non-preprocessed sources to my log file?  I tried to understand how
>>> -save-temps for crash recovery works, but it seems that this runs
>>> outside of the frontend, in the driver.
>>
>> Would dumping unconditionally into some "side channel" -dumpdir be a
>> sufficient workaround?
>
> Of the file names overlap, and it seems in this case, the dump files are
> just overwritten.  I don't see a way to make the file names unique.
>
> I guess for the tough cases, I can just keep running the build under
> strace.

You could override unlink with LD_PRELOAD. Use a special purpose 
filesystem (gitfs? I haven't tried it yet). Wrap gcc with a command that 
calls the true gcc with a different TMPDIR / -dumpdir each time.

-- 
Marc Glisse