Work On Issue 18693 - Remove rndtonl from std.math

[JackStouffer]

This function

1. Results in link errors if you're not using DM's C runtime
2. Is non-standard
3. Is covered by round and friends

Side note: all of these platform specific math functions which share the C names feel a lot like PHP. This is not how these would be designed if std.math was to be written today, so any instance of these that we can remove/redesign, the better.

[dlang-bot]

Thanks for your pull request, @JackStouffer!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✗	18693	normal	std.math.rndtonl and core.math.rndtonl result in link errors

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub fetch digger
dub run digger -- build "master + phobos#6429"

[JackStouffer]

Looks like ddox is mis-parsing the unittest block and including the next function signature

[wilzbach]

Both at the time of deprecation and removal, a changelog entry must be made. This
changelog entry should have a short motivation for the deprecation (or removal)
and should describe which steps can be taken by the user to upgrade their codebase.

(from dlang/DIPs#108)

[wilzbach]

Side note: all of these platform specific math functions which share the C names feel a lot like PHP. This is not how these would be designed if std.math was to be written today, so any instance of these that we can remove/redesign, the better.

Fully agreed. std.math would look quite differently today.

[wilzbach]

@andralex could we get your approval on this one? Thanks!

[andralex]

If semantics are not identical, please specify differences in the deprecation message and changelog. Thanks!

[JackStouffer]

assert(rndtonl(1.0) is -real.nan);

does this function even work at all

[JackStouffer]

does this function even work at all

Nope.