[Issue 19807] undefined reference involving separate compilation, `unittest`, `double`

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19807

--- Comment #3 from ag0aep6g <ag0aep6g at gmail.com> ---
A slight variation with opEquals and opCmp:

----
struct Tuple()
{
    bool opEquals(const Tuple other) const { assert(false); }
    int opCmp(const Tuple other) const { assert(false); }
}
----

Rest as above.

Output:
----
/usr/bin/ld: main.o: in function
`_D14eventcore_core__T5TupleZQh11__xopEqualsFKxSQBt__TQBgZQBkKxQqZb':
main.d:(.text._D14eventcore_core__T5TupleZQh11__xopEqualsFKxSQBt__TQBgZQBkKxQqZb[_D14eventcore_core__T5TupleZQh11__xopEqualsFKxSQBt__TQBgZQBkKxQqZb]+0xe):
undefined reference to
`_D14eventcore_core__T5TupleZQh8opEqualsMxFNaNbNiNfxSQBy__TQBlZQBpZb'
/usr/bin/ld: main.o: in function
`_D14eventcore_core__T5TupleZQh8__xopCmpFKxSQBp__TQBcZQBgKxQqZi':
main.d:(.text._D14eventcore_core__T5TupleZQh8__xopCmpFKxSQBp__TQBcZQBgKxQqZi[_D14eventcore_core__T5TupleZQh8__xopCmpFKxSQBp__TQBcZQBgKxQqZi]+0xb):
undefined reference to
`_D14eventcore_core__T5TupleZQh5opCmpMxFNaNbNiNfxSQBv__TQBiZQBmZi'
collect2: error: ld returned 1 exit status
Error: linker exited with status 1
----

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