libvpx forces the use of clang-3.9

[ryandesign (Ryan Carsten Schmidt)]

The libvpx port forces the use of clang-3.9 on some systems. The comments in the Portfile suggest this is because clang 3.9 was new at the time, and MacPorts would otherwise choose clang 3.7, which was too old.

The situation has now changed, in that clang 3.9 is now old, and it is annoying to have to install this old version when we would rather use clang 5.0 or 6.0. Could you fix the port, please, to prefer newer clangs?

[phriedrich]

It seems it builds fine with the compiler coming with current Xcode 10 on Mojave beta. I just commented out the clang-3.9 requirement and it looks good.

[ryandesign (Ryan Carsten Schmidt)]

My point exactly. MacPorts base added clang 3.9 to the default list of compilers almost 2 years ago. Furthermore, clang 3.9 and earlier don't work properly with the High Sierra SDK or later, and MacPorts base knows that too, so let's let it choose the right compiler, by removing the override from the libvpx port.

See: ​https://github.com/macports/macports-ports/pull/2374

[ryandesign (Ryan Carsten Schmidt)]

In fbc7e5417df7b5ef946edbebaf324883b458132e/macports-ports (master):

libvpx: Append clang-3.9 to compiler.fallback

...rather than prepending it, so that newer MacPorts-selected compilers
will be preferred on newer systems, since clang-3.9 is too old to work
with newer macOS SDKs.

Closes: #56814

[ryandesign (Ryan Carsten Schmidt)]

In 37627404de84d08da852de9e6ba97eda80230b9d/macports-ports (master):

libvpx: Use -fno-integrated-as for clang >= 4 too

The comments indicate this flag should be used for clang 3.5 and later,
so make it actually do that.

See: #56814