svn commit: r457360 - head/Mk/Uses

[Jan Beich]

Alexey Dokuchaev <danfe at FreeBSD.org> writes:

> On Wed, Dec 27, 2017 at 10:41:30AM +0000, Jan Beich wrote:
>
>> New Revision: 457360
>> URL: https://svnweb.freebsd.org/changeset/ports/457360
>> 
>> Log:
>>   Update USES=compiler:c++14-lang to Clang 5.0 on FreeBSD 10
>
> What was the reason behind this change?

Do we really need a reason to update? ;) Here's an incomplete list:

- Many projects don't care about old compilers; Clang support is
  usually driven by OS X and ASan users
- Clang 4.0 is no longer maintained upstream; unlike GCC maintenance
  cycles are very short (around half a year)
- FreeBSD 11.2 (aka /stable/11) and FreeBSD 12.0 (aka /head) already
  use Clang 5.0 in base
- devel/llvm50 can build more ports with -flto=thin -fuse-ld=lld
- Better C++17 support but still incomplete due to old libc++ in base
- Mesa switched to llvm50 in r457264 -> less build dependencies
- www/firefox switched to llvm50 in r457267 -> less build dependencies

> Why on FreeBSD 10, what about 11 and 12-CURRENT?

USES=compiler:c++14-lang is nop for FreeBSD 11 or later because Clang is
new enough to support C++14. To be removed after FreeBSD 10.* reaches EOL.
Architectures stuck with GCC don't differentiate between C++11 and C++14
capable compiler.