[Issue 19888] New: default parameters in templates with tuple parameters+defaults are thrown away

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19888

          Issue ID: 19888
           Summary: default parameters in templates with tuple
                    parameters+defaults are thrown away
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: elpenguino+D at gmail.com

This example fails to compile on all known DMD versions.
```
unittest {
    assert(func(1,0) == 1);
    assert(func(1) == 1); //compile error
    assert(func2() == 0);
}
template AliasSeq(TList...)
{
    alias AliasSeq = TList;
}
T func(T)(T value, AliasSeq!(int) params = AliasSeq!(0))
{
    return value;
}
int func2(AliasSeq!(int) params = AliasSeq!(0))
{
    return 0;
}
```

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