[CF] Unify return types in CFPropertyList again.

[3405691582]

In #2598, we brought the prototypes and declarations into alignment for
_CFPropertyListCreateFiltered and _CFPropertyListCreateSingleValue,
namely, using a Boolean for prototype and declaration, since they were
not matched.

It appears with the Catalina merge they were brought into alignment the
other way around, namely using bool instead. Since the Catalina merge
chose bool, let's just go with that.

[millenomi]

Can't merge.

The issue here is twofold:

• This isn't just Swift's Foundation. This is code from Foundation proper, and it gets sync'd back and forth. It would make sense to clean this up in a vacuum, but…

• … this is an exported symbol, and must remain in the form it is because if I ever merge your change back, it would alter Darwin's Foundation. When a symbol is CF_EXPORT'd, even if it isn't API, it means something may be relying on it, and we need to be binary- and source-compatible there.

So, sorry, no. I reverted it on purpose.

[3405691582]

In #2598, it made the decision to make these both Boolean. As you say, that was not the right choice; they should have been bool. So this PR chooses bool here.

Ultimately, they should be the same, or convertible. When DEPLOYMENT_RUNTIME_SWIFT, Boolean is typedef'd to _Bool, which is convertible to bool, otherwise, it is unsigned char, which isn't: I get a "conflicting types" error when trying to build when not DEPLOYMENT_RUNTIME_SWIFT.

So, if they cannot be the same type in header and implementation, would it be better to change the typedef instead?

[shahmishal]

The Swift project moved the default branch to main and deleted master branch, so GitHub automatically closed the PR. Please re-create pull request with main branch.

More detail about the branch update - https://forums.swift.org/t/updating-branch-names/40412