Some issue with async again:
import vibe.core.concurrency;
auto future = async({
immutable ubyte b = 1;
return b;
});
causes:
/usr/include/dmd/druntime/import/object.d(2876,5): Error: cannot modify immutable expression obj
../../.dub/packages/vibe-d-0.7.28/source/vibe/utils/memory.d(652,37): Error: template instance object.destroy!(immutable(ubyte)) error instantiating
../../.dub/packages/vibe-d-0.7.28/source/vibe/utils/memory.d(678,19): instantiated from here: FreeListObjectAlloc!(immutable(ubyte), true, true, int)
../../.dub/packages/vibe-d-0.7.28/source/vibe/core/concurrency.d(1080,3): instantiated from here: FreeListRef!(immutable(ubyte), true)
../../.dub/packages/vibe-d-0.7.28/source/vibe/core/concurrency.d(1127,1): instantiated from here: Future!(immutable(ubyte))
source/vibe/db/postgresql/package.d(345,28): instantiated from here: async!(immutable(ubyte) function() pure nothrow @nogc @safe, )
dmd failed with exit code 1.