Building application with LDC and -flto=thin fails in link stage

[Seb]

On Wednesday, 28 March 2018 at 16:42:23 UTC, Johan Engelen wrote:
> On Tuesday, 27 March 2018 at 22:10:33 UTC, Per Nordlöw wrote:
>> On Tuesday, 27 March 2018 at 22:00:42 UTC, Johan Engelen wrote:
>>> Indeed.
>>> Please try to manually link first (without dub) by modifying 
>>> the command on which dub errors:
>>>
>>> ```
>>> ldmd2 -flto=thin 
>>> -of.dub/build/application-release-nobounds-lto-linux.posix-x86_64-ldc_2078-F2904BE3C4DA237C077E5C2B0B23442E/knetquery .dub/build/application-release-nobounds-lto-linux.posix-x86_64-ldc_2078-F2904BE3C4DA237C077E5C2B0B23442E/knetquery.o ../../.dub/packages/gmp-d-master/gmp-d/.dub/build/library-release-nobounds-lto-linux.posix-x86_64-ldc_2078-B287F67CE5FF6145BC229790CFB09607/libgmp-d.a phobos-next/.dub/build/library-release-nobounds-lto-linux.posix-x86_64-ldc_2078-F0F2FDB01B8401C04D657BCC145D46A5/libknet_phobos-next.a -L--no-as-needed -L-lzstd -L-lgmp -L-lc -L-lreadline -L-lz -L-lbz2
>>> ```
>>>
>>> -Johan
>>
>> Yes, that works!
>
> Good :-)
>
> I'm no dub expert and I don't know how to pass flags to the 
> _compiler_ for the link step.
> Would be good to figure that out with the dub folks.
>
> There will be similar problems with using ASan (and fuzzer 
> aswell):  `-fsanitize=address` must also be passed to the D 
> compiler (not the linker) during linking such that the correct 
> asan library is linked into the executable.
>
> - Johan

dub supports dflags and lflags in the config file. lflags are the 
linker commands.

http://code.dlang.org/package-format?lang=sdl#build-settings

You can also specify per platform arguments, e.g.

dflags "-version=BuildingWithLDCRocks" platform="ldc"

(dub even supports the environment variables DFLAGS which dmd 
doesn't (and of course LFLAGS))