Bug 1689031

Description of problem:

I'd like to use llvm/clang to cross-compile to ppc64/ppc64le from x86_64.

I'd also like to target NVPTX from ppc64/ppc64le.

With a TALOS workstation I'd like WebAssembly fromppc64le like rhbz#1662559 too.

More generally I'd like all targets enabled because getting a cross-compiler when one isn't available is time consuming.

llvm by default has LLVM_TARGETS_TO_BUILD=all (https://llvm.org/docs/CMake.html#llvm-specific-variables) however Fedora restricts these https://src.fedoraproject.org/rpms/llvm/blob/f29/f/llvm.spec#_18.

Can we use a bit more build time and install space and just have these back to the default of all to save incremental additions like rhbz#1662559 and rhbz#1627500?

I understand it wasn't too long ago that these where reduced however it would be good to have a fully featured clang like in Ubuntu:
https://src.fedoraproject.org/rpms/llvm/c/b772b3b219546d9bfaadfc2f715a446914088187

Very roughly looking at packages across versions this might be 25% / 8MB extra. There's buildroot for space contentious distros and I don't think its Fedoras market.

Version-Release number of selected component (if applicable):

Name         : llvm
Version      : 7.0.1
Release      : 3.fc29
Architecture : x86_64
Size         : 15 M
Source       : llvm-7.0.1-3.fc29.src.rpm
Repository   : @System
From repo    : updates

$ clang -v
clang version 7.0.1 (Fedora 7.0.1-4.fc29)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-redhat-linux/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-redhat-linux/8
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-redhat-linux/8
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64

How reproducible:

Steps to Reproduce:
1. clang -target powerpc64le /tmp/m.c

Actual results:

error: unable to create target: 'No available targets are compatible with this triple.'
1 error generated.

Expected results:

success.