On Tuesday, 3 December 2019 at 10:30:34 UTC, mipri wrote: > Likewise this fails, but would succeed if foo were moved > out of the unit test: > > unittest { > void foo(int x) { writeln(x); } > > 42.foo; > } Not a forward reference error, local symbols are excluded from UFCS (see https://dlang.org/spec/function.html#pseudo-member)