https://issues.dlang.org/show_bug.cgi?id=21003
--- Comment #1 from Stanislav Blinov <stanislav.bli...@gmail.com> --- Further reduction, `bar` doesn't need to be a template, e.g. struct S { void foo(int value) { bar(() => value); } void bar(int delegate() dg = () => 0) { import std.stdio; writeln(dg()); } } bug.d(8): Error: delegate bug.S.__lambda3 cannot be struct members --