test: Disable dshell/dll.d test on OSX

[ibuclaw]

When running the dll test, the following warning is written to console.

user@darwin20:~/src/dlang/dmd/test$ ./test_results/dshell/dll/testdll
Shared libraries are not yet supported on OSX.

This is correct, as when you link druntime into a shared library on OSX, all the symbols of libphobos.a are copied into the DSO/image for that library. Then, linking an executable with both libphobos and that library means there are now two copies of all globals present at run-time.

i.e:

user@darwin20:~/src/dlang/dmd/test$ otool -L test_results/dshell/dll/testdll
test_results/dshell/dll/testdll:
	test_results/dshell/dll/mydll.so (compatibility version 0.0.0, current version 0.0.0)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1292.100.5)

user@darwin20:~/src/dlang/dmd/test$ nm test_results/dshell/dll/testdll | grep __D4core6thread10threadbase10ThreadBase6_slockG96v
00000001000399e8 B __D4core6thread10threadbase10ThreadBase6_slockG96v

user@darwin20:~/src/dlang/dmd/test$ nm test_results/dshell/dll/mydll.so | grep __D4core6thread10threadbase10ThreadBase6_slockG96v
0000000000057c58 B __D4core6thread10threadbase10ThreadBase6_slockG96v

Unlike ELF DSOs, where at run-time these are resolved as-if the symbol is weak. On OSX, depending on which DSO/image a referencing function is resolved/called from, you could get either version of these symbols. i.e: Thread.initLocks() is called from testdll.exe, initializing the Thread.slock@1000399e8 handle in that image, but thread_suspendAll is called from mydll.so, which tries to use the uninitialized Thread.slock@000057c58 and throws an Error as a result.

Until DMD sorts out symbol emission to avoid this (GDC annotates these __gshared variables with @weak IIRC), or gains proper support for shared libraries, it can only be considered a fluke that this test even passes. Disabling it unblocks #14194.

[dlang-bot]

Thanks for your pull request, @ibuclaw!

Bugzilla references

Your PR doesn't reference any Bugzilla issue.

If your PR contains non-trivial changes, please reference a Bugzilla issue or create a manual changelog.

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + dmd#14208"

[WalterBright]

I added a bugzilla for it: https://issues.dlang.org/show_bug.cgi?id=23180