Merge pull request #403 from vibe-d/issue_138_immutable_task_arguments

Allow immutable arguments to be passed to task callbacks. Fixes #138.

source/vibe/core/task.d

@@ -819,6 +819,7 @@ package struct TaskFuncInfo {
 			typedCallable!CALLABLE = callable;
 			foreach (i, A; ARGS) {
 				static if (needsMove!A) args[i].move(typedArgs!TARGS.expand[i]);
+				else static if (is(A == immutable)) *cast(Unqual!A*)&typedArgs!TARGS.expand[i] = *cast(Unqual!A*)&args[i];
 				else typedArgs!TARGS.expand[i] = args[i];
 			}
 		} ();

source/vibe/core/taskpool.d

@@ -471,3 +471,13 @@ nothrow @safe:
 		return true;
 	}
 }
+
+
+unittest { // #138 - immutable arguments
+	auto tp = new shared TaskPool;
+	struct S { int[] x; }
+	auto s = immutable(S)([1, 2]);
+	tp.runTaskH((immutable S s) { assert(s.x == [1, 2]); }, s)
+		.joinUninterruptible();
+	tp.terminate();
+}