ProcNotation followed by anonymous fun parameter breaks on macro interpolation

[HertzDevil]

This is valid code, because parameters of lib funs do not require a name:

lib Foo
  # first parameter is `x : ::Proc(Int, Int)`
  # second parameter is ` : Int`
  fun foo(x : Int -> Int, Int)
end

Macro interpolation of the above AST node adds a pair of parentheses around the ProcNotation restriction:

lib Foo
  fun foo(x : (Int -> Int), Int) # Error: expecting token '->', not ')'
end

It appears the parser is expecting another ProcNotation around those types, e.g.:

fun foo(x : (Int -> Int), Int -> Void) # Proc(Proc(Int, Int), Int, Void)

Either the syntax should allow this, or those parentheses should be dropped. This appears in the Bionic bindings and is not a typo:

# src/lib_c/aarch64-android/c/pthread.cr
lib LibC
  fun pthread_create(__pthread_ptr : PthreadT*, __attr : PthreadAttrT*, __start_routine : Void* -> Void*, Void*) : Int
end

Related: #11966

[HertzDevil]

As expected, this applies to normal Calls as well (item 4 on #11966):

macro f(x)
  {{ x.args.map(&.stringify) }}
end

f(foo(x : T, U -> V, Foo))   # => ["x : (T, U -> V)", "Foo"]
f(foo(x : (T, U -> V), Foo)) # Error: expecting token '->', not ')'