Using clang as the system compiler

[goatcheese]

I've seen attempts many times over the years to use clang globally & with the recent release of llvm 6 I figured I'd give it. To be precise on what 'using clang' means - swapping out gcc, g++, ar, as, nm, and libunwind with their llvm/clang equivalents. No compiler-rt, no libc++, no lld. Also not using LTO, though thinlto looks rather interesting. Perhaps at a later date.

TL;DR most everything build fine

I found the following links useful as starters.
https://wiki.gentoo.org/wiki/Clang
https://blogs.gentoo.org/gsoc2016-native-clang/2016/08/14/use-clang-as-a-native-compiler-in-gentoo
I also quickly realized that a lot of information available is outdated & not completely accurate given how quickly this stack has developed.

This is a multilib unstable install using profile 17.1. The primary modifications to make.conf were

[Juippisi]

I used to have clang as my main compiler .... some time ago (when chromium was still faster to compile with clang)

I remember having a lot more packages that failed, nice to see its made some progress!

I still keep an eye of gcc vs. clang comparisons in phoronix.com web site, and they do seem rather similar. Nowadays Im using gcc with O3, graphite and LTO so I believe thats a "faster" setup because graphite optimizations are not available in clang. I used to follow this guy, https://github.com/fsvm88/gentoo-portage_etc/ when he used clang as his main compiled. He's moved to gcc now and only uses clang with specific packages.

But looks like with GCC-8 just behind the corner and clang-6 just released, GCC will take a huge step forward and pass clang in where clang used to shine.

[lyallp]

I have had a VirtualBox VM on my Gentoo system, running Gentoo built with Clang.
Whenever I came across a package that didn't build, I stuffed it in my package.env file.
Below is the current contents of my package.env file (specific packages that appeared to require gcc, rather than clang to compile.
Not that many, but then the VM is a basic Gentoo system using fluxbox window manager, not gnome or kde.

Edit: And, just for giggles, I occasionally do an "emerge --emptytree @world"

[42n4]

I understand why people go to gcc 8.1.0 lto graphite
I used your list and