Swift: Possible improvement to ApplyExpr.toString

[geoffw0]

Possible improvement to ApplyExpr.toString.

The first three commits were originally part of #9737 (but have since been removed from there), where @MathiasVP said:

I like the output a lot more now, but I'm not sure we're getting the improved output for the right reasons. It looks like we're now generating "call to f()" when we can resolve the call to a static call target f, but we print just "f()" when we cannot resolve it to a target.

The reason the output looks a lot better now is that the cases where there isn't a static call target are all examples where getFunction returns a strange DotSyntaxCallExpr (or SelfApplyExpr, or ConstructorRefCallExpr) which all have strings that look like "call to f()" (because they fall into the category of calls where we can resolve the target).

For example, I think the call to bar() in the example below will get a confusing toString (since it'll just be the string "bar" and not "call to bar" even though it's a call to bar and not a reference to the variable).

func foo(_ bar: () -> ()) {
  bar()
}

foo({ print("I am a lambda :wave:") })

As a fourth commit I've added the above as a test and it works (or rather doesn't) as anticipated. The obvious fix would be to make a special case for DotSyntaxCallExpr vs everything else, but that might just be a rabbit hole of special cases - ideally I would like to find a cleaner answer.

[geoffw0]

Waiting on internal issue (github/codeql-c-team#1019).