[Sema] Correct 'await' insertion fixIt

[jameesbrown]

Note this is a duplicate of a previously open pull request I'd closed accidentally: #71716
Resolves #65913

use fixItInsertAfter with the specialized fixIt given it is an implicit DeclRefExpr.

My reasoning is that I saw in ParseStmt.cpp, where we parse a shorthand optional binding we have:

else if (!ThePattern.getPtrOrNull()->getBoundName().empty()) {
    auto bindingName = DeclNameRef(ThePattern.getPtrOrNull()->getBoundName());
    auto loc = DeclNameLoc(ThePattern.getPtrOrNull()->getEndLoc());
    auto declRefExpr = new (Context) UnresolvedDeclRefExpr(bindingName,
                                                           DeclRefKind::Ordinary,
                                                           loc);
    
     declRefExpr->setImplicit();
     Init = makeParserResult(declRefExpr);
```.

[AnthonyLatsis]

@swift-ci please smoke test macOS

[jameesbrown]

I see a test failed, but I am a bit confused by the failure.

[AnthonyLatsis]

The failure is not related.

[jameesbrown]

@AnthonyLatsis @LucianoPAlmeida I've made some updates based off your suggestions. I first tried implementing a traversal through StmtConditionElements by following ArgumentList as an example but somehow free was being called twice on my Walker and I was getting exceptions in my walkToStmtConditionElementPost. I didn't figure that part out but it did lead me to understand the code a bit more. I realized that what was making this more complicated than it should be was that we were walking too far in the case of a shorthand optional binding. What I did was make a small change in walkToAnchor so that we stop if we see an implicit DeclRefExpr. I then cleaned up the code a little by moving the creation of the fixit to its own function.

[LucianoPAlmeida]

@swift-ci Please smoke test

[LucianoPAlmeida]

It seems good to me, but wait for code owners review before merging :)
cc @xedin

[jameesbrown]

@xedin When you have some time - Could you take a look at this please?

[xedin]

Sorry I missed this, will add it to the queue for Monday!

[xedin]

I didn’t forget about this, will take a look tomorrow!

[xedin]

Thank you!

[xedin]

@swift-ci please smoke test

[AnthonyLatsis]

Good job!

[AnthonyLatsis]

Please consider tidying up the commit message. NB: I do not recommend including a link to the issue because it spawns permanent commit activity items in the issue every time you force-push, but if you wish to, please place the link in the body rather than the title.

[jameesbrown]

@AnthonyLatsis I will do this (tidy up commit message) and I see your point about linking the issue; I'll avoid doing that in the future.

[jameesbrown]

@AnthonyLatsis Following the guidelines I cleaned up the commit message, I also have removed some of the not needed test functions you had pointed out. Thank you for all your reviewing! It is much appreciated.

[AnthonyLatsis]

@swift-ci please smoke test