Invalid interpretation of the code caused by misleading parenthenses.
1. false && print ('')
   -> false && (print (''))
   -> false && 1
   -> false
2. print('') && false
   -> (print (('') && false))
   -> (print false)
   -> 1
   -> true
3. print('') && false && false
   -> (print ((('') && false) && false))
   -> (print false)
   -> 1
   -> true
4. (print('') && false) && true
   -> ( print (('') && false) ) && true
   -> (print false) && true
   -> 1 && true
   -> true
5. (print('') && false) && false
   -> (print (('') && false) && false
   -> (print false) && false
   -> 1 && false
   -> false

I believe that documentation for all language constructs (`echo`, `include`, `print`, ...) should explicitly discourage use of parenthenses around arguments. They're very misleading.

Oh, I see what happened.  I agree with your recommendation.  The documentation 
says they are "not required" (implying optional), and they are used in the 
actual example.  I normally use echo, and without parens, so I just kinda 
randomly came across this.

I'm not sure if you were saying the parser's interpretation was invalid or mine, 
but in case the latter and this is considered correct parsing, the documentation 
should be updated to reflect that it's "print <string>", without parens.  
Developers can deduce for themselves that "print ('foo')" is allowed, but the 
semantics will be clearer.

Your interpretation was invalid. This is a common pitfall. The documentation is very misleading, since it states that parenthenses are optional. This suggests that they're a part of the language construct itself and work like parenthenses in a function call. Unfortunely they aren't. They're interpreted as a part of an expression that is later passed to `print` (`echo`, `include` and similar). They have nothing to do with "function" itself. A nice example that shows this issue is the following snippet:
  print(string) TRUE;

I have posted a request (#60698) to change documentation.

Roger that.  Thanks for clarifying.  Closing ticket.