std.parallelism giving inscrutable error messages

[dlangBugzillaToGithub]

deadalnix (@deadalnix) reported this on 2016-01-12T13:34:08Z

Transfered from https://issues.dlang.org/show_bug.cgi?id=15558

Description

struct Host {
	@disable this(this);
}

void main() {
	uint[] arr;
	
	import std.parallelism;
	auto hostmap = taskPool.map!(function Host(uint a) {
		return Host.init;
	})(arr);
}


Gives me:

/Library/D/dmd/src/phobos/std/parallelism.d(1677): Error: cannot interpret (uint[], ulong, Host[]) at compile time
/Library/D/dmd/src/phobos/std/parallelism.d(1677): Error: static assert  __error
/Library/D/dmd/src/phobos/std/parallelism.d(1996):        instantiated from here: amap!(uint[], ulong, Host[])
fail.d(11):        instantiated from here: map!(uint[])

Turns out the @disable this(this); is key in triggering the error.

[thewilsonator]

This now gives

/dlang/dmd/linux/bin64/../../src/phobos/std/parallelism.d(2179): Error: struct `onlineapp.Host` is not copyable because it has a disabled postblit
onlineapp.d(11): Error: template instance `std.parallelism.TaskPool.map!(function Host(uint a) pure nothrow @nogc @safe => Host()).map!(uint[])` error instantiating