Swift: Improvements related to the swift/cleartext-logging query.

[geoffw0]

Improvements related to the swift/cleartext-logging query:

• model flow through getVaList (so that we can pass the NSLogv test cases).
• add data flow through variadic arguments (this will have effects more widely than the swift/cleartext-logging query and is separately tested).
• add an allowImplicitRead for array content sinks in the swift/cleartext-logging query (so that, together with the previous bullet point, we can pass the NSLog and more of the print test cases).
• add more sinks for the swift/cleartext-logging query.

[geoffw0]

Fixed merge conflicts.

@MathiasVP possibly VarargExpansionExpr is yet another example of something that should be hidden from the AST instead of having a special case in data flow? As far as I can tell where varargs are used a VarargExpansionExpr wraps the ArrayExpr entering the call.

[MathiasVP]

Fixed merge conflicts.

@MathiasVP possibly VarargExpansionExpr is yet another example of something that should be hidden from the AST instead of having a special case in data flow? As far as I can tell where varargs are used a VarargExpansionExpr wraps the ArrayExpr entering the call.

Good point. Looking at https://github.com/apple/swift/blob/main/include/swift/AST/Expr.h#L3566 it looks like there are plans to have surface-level syntax for VarargExpansionExprs. Once we have surface-syntax for it I don't think we want to hide it from the AST?

[geoffw0]

Looking at https://github.com/apple/swift/blob/main/include/swift/AST/Expr.h#L3566 it looks like there are plans to have surface-level syntax for VarargExpansionExprs.

Sounds like I should probably leave it as a data flow solution then, at least, for now.

[geoffw0]

DCA LGTM.

Merge conflicts fixed (again).

[geoffw0]

Fixed merge conflicts again.

[MathiasVP]

LGTM!