LDC LTO proper flags

[kinke]

On Friday, 13 October 2023 at 09:37:49 UTC, Sergey wrote:
> Based on experience on Debian 
> (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=960157) 
> Docker image I found I was required to use 
> "-flto-binary=/usr/lib/LLVMgold.so" in addition to "-flto=full".
>
> Is it Debian specific issue or required for other distributions 
> as well?

It's not required for the official prebuilt packages, as they 
bundle the plugin directly. `/usr/lib/LLVMgold.so` is in the 
default search path, so should be found automatically, unless 
Debian have patched this: 
https://github.com/ldc-developers/ldc/blob/60e45d619a00e32f79976c9e0047a7828d47c1ea/driver/linker-gcc.cpp#L114

> For example on Archlinux the liblphobos package provides two 
> files:
> - usr/lib/libdruntime-ldc-lto.a
> - usr/lib/libphobos2-ldc-lto.a
>
> So probably adding 
> "-defaultlib=phobos2-ldc-lto,druntime-ldc-lto" will be fine.

This is a separate thing, to be used explicitly when wanting to 
LTO druntime and Phobos too, not just your code. It implies that 
these libs are linked statically then.