[rb-general] [PATCH] gcc: read -fdebug-prefix-map OLD from environment (improved reproducibility)

[Daniel Kahn Gillmor]

On Thu 2015-12-10 18:59:33 -0500, Joseph Myers wrote:
> On Thu, 10 Dec 2015, Daniel Kahn Gillmor wrote:
>
>> Specifically, if the first character of the "old" argument is a
>> literal $, then gcc will treat it as an environment variable name, and
>> use the value of the env var for prefix mapping.
>
> I don't think a literal $ in option arguments is a good idea; it's far too 
> hard to pass through a sequence of shells and makefiles that you typically 
> get in recursive make.  You end up with things like 
> '-Wl,-rpath,'\''\\\$$\$$\\\$$\$$ORIGIN'\''/../' (part of a process for 
> using $ORIGIN when linking GDB) if you try.

yow, that's truly monstrous!

Is there a different symbol or string you'd be OK using instead for the
same approach?  What about looking for an "ENV:" prefix?

so something like:

 -fdebug-prefix-map=ENV:SOURCE_BUILD_DIR=/usr/src

wdyt?  I could rework the patch pretty easily if that seems acceptable.

        --dkg