DMD2 vs LDC2 inliner

[Nicholas Wilson]

On Monday, 25 February 2019 at 02:49:36 UTC, James Blachly wrote:
> Any ideas why DMD2 cannot inline this, but LDC2 has no problem 
> doing so -- or suggestions for what I can do to make DMD2 
> inline it?
>
> Alternatively, I could version(DigitalMars) and version(LDC), 
> but AFAICT this requires me to duplicate the entire template, 
> because I cannot figure out how to make the version() directive 
> apply only to the pragma.
>
> Template instantiation is with a simple struct having integer 
> members start and end.
>
> Thanks in advance for tips.
> ---
> pragma(inline, true)
> bool overlaps(IntervalType1, IntervalType2)(IntervalType1 int1, 
> IntervalType2 int2)

Leaving aside the issue of why DMD can't handle this, the entire 
reason
pragma(inline, bool) takes a bool is for it to be (potentially) 
predicated.
In this case you want:

version(DigitalMars)
      private enum inline_overlaps = false;
else // assuming GDC is good
      private enum inline_overlaps = true;

pragma(inline, inline_overlaps)
bool overlaps(IntervalType1, IntervalType2)(IntervalType1 int1, 
IntervalType2 int2)
{
      return ...;
}