[PATCH] D26579: [cmake] Allow CMAKE_BUILD_TYPE=Gentoo

[Mehdi AMINI via llvm-commits]

mehdi_amini added a comment.

In https://reviews.llvm.org/D26579#593711, @mgorny wrote:

> In https://reviews.llvm.org/D26579#593702, @mehdi_amini wrote:
>
> > There is a good reason Gento is doing it: to make sure they have full control over compiler flags in the Gentoo configuration.  See here: https://github.com/coreos/portage-stable/blob/master/eclass/cmake-utils.eclass#L43
> >
> > However accepting the value "Gentoo" here won't address the problem, it'll just mask it. We are expecting values from this list in multiple place.
>
>
> Yes. I can volunteer to make sure that Gentoo appears there whenever desired, if that's what you need.


That's not what *I* need, that's what *you* need.

> 
> 
>> For example in llvm/cmake/modules/HandleLLVMOptions.cmake:
>> 
>>   # On non-Debug builds cmake automatically defines NDEBUG, so we
>>   # explicitly undefine it:
>>   if( NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG" )
>>    
> 
> Just to be clear, here 'Gentoo' is not expected since CMake doesn't control -DNDEBUG for this build type.

But here we're gonna add "-UNDEBUG" when the build type is Gentoo, is it OK?

> 
> 
>>   if (NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "DEBUG" AND
>>       NOT uppercase_CMAKE_BUILD_TYPE STREQUAL "RELWITHDEBINFO")
>>     add_flag_if_supported("-gline-tables-only" GLINE_TABLES_ONLY)
>>   endif()
>>    
> 
> …and here it's not expected since appending -g flags implicitly is against a Gentoo policy.

Right, and with BUILD_TYPE=Gentoo this will add "-gline-tables-only".

I don't know what is the right thing for each of these cases, and this alone shows that you'll need to have a clear description and requirement for this "special" build type if you expect to have it supported upstream.


https://reviews.llvm.org/D26579