RFR: 8326685: Linux builds not reproducible if two builds configured in different build folders

[Andrew Leonard]

On Tue, 27 Feb 2024 10:59:54 GMT, Andrew Leonard <aleonard at openjdk.org> wrote:

>> Also, this mapping business is getting really convoluted. :-( I did not like it as it was, and this patch makes it even worse. I think we need to rewrite this to create some kind of dict/map, and then iterate over the map and apply `-fdebug-prefix-map` to all items in the map. Unfortunately, the data structures available in shell scripts is limited and will make this a bit tricky to pull off. :(
>
>> It seems correct to include the output dir in the remapping, but I have two objections/questions to the way you are doing it.
>> 
>>     1. Why not just use OUTPUTDIR instead of the two specialized subdirs? That is simpler, more general and future-proof.
>> 
>>     2. Why not expand the value of the OUTPUTDIR variable? I.e.
>> 
>> 
>> ```
>>  DEBUG_PREFIX_CFLAGS="$DEBUG_PREFIX_CFLAGS -fdebug-prefix-map=$OUTPUTDIR/="
>> ```
>> 
>> instead of trying to preserve it as a variable to be expanded in the make execution.
> 
> Ah thanks @magicus I hadn't seen that existed! that would simplify it, i'll try that now

> Also, this mapping business is getting really convoluted. :-( I did not like it as it was, and this patch makes it even worse. I think we need to rewrite this to create some kind of dict/map, and then iterate over the map and apply `-fdebug-prefix-map` to all items in the map. Unfortunately, the data structures available in shell scripts is limited and will make this a bit tricky to pull off. :(

yeah, although that's not easy for example for the gcc include paths that we have to work out based on the users compiler paths, so it wouldn't be a simple dict

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PR Review Comment: https://git.openjdk.org/jdk/pull/18009#discussion_r1504046943