const assert = @import("std").debug.assert; fn get_foo() fn (*u8) usize { comptime { return struct { fn func(ptr: *u8) usize { var u = @ptrToInt(ptr); return u; } }.func; } } test "define a function in an anonymous struct in comptime" { const foo = get_foo(); assert(foo(@intToPtr(*u8, 12345)) == 12345); }