#zig build-obj {
--name test -fno-emit-bin
-Mroot=test.zig
#}

#write test.zig {
export fn foo() void {
    const U = extern union {};
    _ = @as(U, undefined);
}
#}
#update
#check errors {
test.zig:2:22: error: extern union has no fields
#}
