meson: Don't use -Wl,-no_weak_imports on <= 10.6

[ryandesign]

Description

meson: Don't use -Wl,-no_weak_imports on Mac OS X 10.6 and earlier.

This is a temporary workaround for build failures affecting any port that uses meson's has_function check and clang 8 or later on Mac OS X 10.6 and earlier.

Closes: https://trac.macports.org/ticket/60017
Closes: https://trac.macports.org/ticket/60308

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 10.6.8 10K549
Xcode 3.2.6 DevToolsSupport-1806.0 10M2518

Verification

Have you

• followed our Commit Message Guidelines?
• squashed and minimized your commits?
• checked that there aren't other open pull requests for the same change?
• referenced existing tickets on Trac with full URL?

• checked your Portfile with port lint?
• tried existing tests with sudo port test?
• tried a full install with sudo port -vst install?
• tested basic functionality of all binary files?

[macportsbot]

Notifying maintainers:
@SoapZA for port meson.

[ryandesign]

After this is merged we should force a build of all ports that depend on meson on the 10.6 buildbot workers since it's been broken for so long.

[macportsbot]

Travis Build #11893 Failed.

Lint results

--->  Verifying Portfile for meson
--->  0 errors and 0 warnings found.

Port meson success on xcode10.3. Log
Port meson's dependencies fail on xcode9.4. Log
Port meson success on xcode8.3. Log
Port meson success on xcode7.3. Log

[kencu]

Although getting rid of the irritating flag is nice, I don't understand how it is passing the test to get added.

The test is supposed to be testing the Xcode version, and this is 3.2.6 on Leopard.

The test is supposed to have nothing whatsoever to do with the version of clang.

Anyway, dropping the flag is good -- what is really going on here is unclear.

[kencu]

3.2.6 on SnowLeopard, I meant.

[kencu]

One more --as the no_weak_imports flag is supported only as of Xcode 8, the presence of this flag should cause the same linker errors on every system less than Xcode 8. -- what is that? 10.11?

Reading through the meson source (is a tangled web...) I think they try to map all clangs back to an llvm equivalent -- although I haven't found that exact bit of code that does that yet -- and then they do indeed try to equate clang 8.0 means Xcode 8.0 means the linker should support this flag.

[SoapZA]

I'm fine with this. @ryandesign can we get this upstreamed?

[kencu]

It's not upstreamable (it just deletes a chunk of code they specifically added to fix an issue) -- although upstream is trying to sort out what the real solution might be.