[Swift] Undo parsing function calls with trailing closure

[dan-zheng]

Patches some type name bugs, addressing #861.
Fixed examples:

Edit: after careful consideration, I decided to revert parsing function calls with trailing closure.
It's not possible to perfectly identify such function calls using the current lexer and the feature causes more harm than good.

[dan-zheng]

Done patching and ready for merging.
Generic functions are also parsed correctly now.

Before:

After:

[johnfairh]

Thanks for looking!

It would be worth your checking the html diffs of visual/samples/swift between Rouge 3.0.0 and this change: there are still quite a few false-positive differences where 'identifier-followed-by-{<' are unintentionally matching as function names.

Easiest is keywords like else { and didSet {. Basically anything that can precede a {.

Trickier than that, there are cases to think about like (not claiming exhaustive list):

if a && b { // 'b' looks like a function name by the '{' rule
if let a = b { // same
if a < b { // 'a' looks like func name by the '<' rule, 'b' also by the '{' rule
switch A(b).c { // 'c' looks like a function name
for _ in 1...amountToPad { // 'amountToPad' looks like a function name

infix operator <> : ComparisonPrecedence // 'operator' looks like a function name by the '<' rule

In some of these it's ambiguous whether the identifier is being used as a function call or not without the rest of the statement. I think this might be a limitation of how this lexer is set up, not sure there is a perfect solution without a bigger rewrite to fully deal with Swift grammar taking much more context into account.

[dan-zheng]

Wow, thanks for the thorough analysis!
Yes, I agree that a perfect solution would require taking context into account - otherwise it's generally impossible to distinguish variable names/function names/type names. A halfway solution could be to maintain longer lists of built-in types and functions, but it's not really robust.

I suppose I should partially roll back #837 and undo function calls with lambda argument since that seems to cause more harm than good.

[johnfairh]

Sounds good.

[gfx]

Thanks! It looks good.