Bug 8018 – Template fails to instantiate with templated argument

version=Fail; enum Enum { Foo } struct Stub { } template Temp(alias T) { alias Stub Temp; } struct Foo { auto call(Enum en)() { Stub arg; test!en(arg); return arg; } version(Fail) { void test(Enum en)(Temp!en arg) if (0) {} void test(Enum en)(Temp!en arg) if (1) {} } else version(Ok) { void test(Enum en)(Stub arg) if (0) {} void test(Enum en)(Stub arg) if (1) {} } } void main() { Foo foo; foo.call!(Enum.Foo)(); } This fails with: test.d(14): Error: template test.Foo.test does not match any function template declaration test.d(14): Error: template test.Foo.test cannot deduce template function from argument types !(cast(Enum)0)(Stub) test.d(40): Error: template instance test.Foo.call!(cast(Enum)0) error instantiating You can comment out the test template in the version(Fail) that has this constraint: "if (0) {}" and it will compile again. You can also version=Fail to version=Ok then it will compile. The version=Ok code doesn't instantiate the Temp template and this seems to work. But both versions should work because both templates resolve the type as a Stub struct.

Ok there's another workaround, just make the last type implicit: void test(Enum en, StubType)(StubType arg) So maybe it's not a major bug. :)

Works in 2.063.2.