Fix issue 16667: dub test fails on std.conv after upgrade to dmd 2.072.0

[mihails-strasuns]

https://issues.dlang.org/show_bug.cgi?id=16667

[dlang-bot]

Fix	Bugzilla	Description
✓	16667	[REG] dub test fails on std.conv after upgrade to dmd 2.072.0

[wilzbach]

Thanks a lot :)
We really should start to test a couple of external projects on EVERY PR/merge.

[mihails-strasuns]

@wilzbach this is on priority list for me and Martin as soon as 2.072.1 is out (see http://forum.dlang.org/post/rsxfyebqlrryoblhylml@forum.dlang.org)

[JackStouffer]

The right fix here is not to add back in the hacks in std.uni. The right fix is to use isConvertibleToString and StringTypeOf. I am working on a PR for this now.

[mihails-strasuns]

@JackStouffer this is stable branch, we must not wait until someone works on proper fix, possibly making mistake again and making things even more complicated. PR breaks stuff - it gets reverted, it must be as simple as that.

And with release becoming usable again you can re-create same PR again towards master.

[mihails-strasuns]

This reminds me that I should add regression test for reverted stuff though.

[mihails-strasuns]

Added 6747380 as a regression test for future re-implementation of original PR

[JackStouffer]

Probably want to add another test for toUpper

[WalterBright]

Please edit PR title with a more informative one. The format for a bugzilla fix should be:

fix Issue NNNN: title of the bugzilla issue

[mihails-strasuns]

@WalterBright this PR contains fixes for 2 bugzilla issues. Do you want each be separate PR?

[mihails-strasuns]

Have split second fix into own PR: #4901

[mihails-strasuns]

Closing in favor of #4905