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

[Daniel Kahn Gillmor]

On Thu 2015-12-10 19:12:57 -0500, Daniel Kahn Gillmor wrote:
> 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.

I've re-rolled the patch (attached below, here) to use the ENV: prefix
instead of the $.

I've also updated the patch on
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68848 to match this
approach.

Thanks for the input, Joseph.

Regards,

        --dkg

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