[clang] Choose non-templated ctor as deduction guide unambiguously

[HoBoIs]

If there are two guides, one of them generated from a non-templated constructor
and the other from a templated constructor, then the standard gives priority to
the first. Clang detected ambiguity before, now the correct guide is chosen.
The correct behavior is described in this paper: http://wg21.link/P0620R0

Example for the bug: http://godbolt.org/z/ee3e9qG78

As an unrelated minor change, fix the issue #64020,
which could've led to incorrect behavior if further development inserted code after a call to
isAddressSpaceSubsetOf(), which specified the two parameters in the wrong order.

[HoBoIs]

@zygoloid @yuanfang-chen @faisalv @OleStrohm
Could you review my commit and/or suggest more appropriate reviewers?
Thanks in advance!

[cor3ntin]

@erichkeane

[erichkeane]

This seems right to me, however we need to do 2 things:

1- This needs a release note.

2- We need to track down when this changed in the standard, and why. If it was a DR, we need to do make sure we update that we've implemented that DR. If it was a normal paper, we need to figure out which versions of the standard it applies to and do THAT correctly. Either way, we'd have to update the paper tracking doc.

[shafik]

I added a comment in the issue her: #67959 (comment)

Please make sure to add references to the standard in appropriate places in this PR.

[HoBoIs]

The paper where this came from is: https://wg21.link/P0620R0. most of this paper was already implemented.
Where is the paper tracking doc I need to update? https://clang.llvm.org/cxx_status.html claims this paper is implemented.
Sorry if the following questions are trivial, I'm new to this.
In the release note should I put it under Bug Fixes to C++ Support or Bug Fixes in This Version?

Where should I reference the standard in the PR? In the Description?

[HoBoIs]

Deduction guides were added in C++17, and This paper is also in C++17, so I don't think we need to check for versions in the code (I don't create any deduction guides I just use them so before C++17 my code is never used).

[erichkeane]

The paper where this came from is: https://wg21.link/P0620R0. most of this paper was already implemented. Where is the paper tracking doc I need to update? https://clang.llvm.org/cxx_status.html claims this paper is implemented. Sorry if the following questions are trivial, I'm new to this. In the release note should I put it under Bug Fixes to C++ Support or Bug Fixes in This Version?

Where should I reference the standard in the PR? In the Description?

cxx_status.html is the paper tracking doc, if we claim it was already implemented than there is nothing to do there.

For release notes, ForC++Support seems like the right area for me.

I've confirmed that P06020R0 is in N4659 (Final draft for C++17), so you're right, there is no version checking we have to do. Thanks for doing the leg work here!

[erichkeane]

Just need a period after the note, otherwise LGTM!

[shafik]

Thank you for the follow-up work.

LGTM

[HoBoIs]

@erichkeane @shafik I don't have write access. Could you merge if there is nothing to be done?

[whisperity]

LGTM with previous discussion. I will do the commit... On the UI... 🙂

[whisperity]

TIL there is no way to resign a review here like there was on Phab...

[erichkeane]

I had permissions, so I squash/merged.

[whisperity]

It looks like the authorship metadata was set up incorrectly in the commits, note the typo: @gmial.com. I was in the process of fixing the things locally.

[erichkeane]

Ah, I see, apologies. I thought you meant the resign/etc complaint meant you couldn't commit through the UI.