[GROOVY-11137] Improve support for union and intersection types

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: parser-antlr4, Static Type Checker

Language

groovy

• Assignee: Unassigned
• Reporter: Eric Milles
• Created: 29/Jul/23 13:03
• Updated: 30/Jul/23 14:04

Description

Union types are partially supported:

try {
 foo()
} catch (Exception | Error e) { // parses
  e.printStackTrace() // flow type of e is probably Throwable but should be (Exception | Error)
}

But don't have direct representation or support in the AST.

Intersection types (declared with &) are not supported:

// parses as method call: (a & b).call({ ... })
var fun = (Function<String,String> & Serializable) { x -> x }

void test(Number number) {
  if (number instanceof Comparable) {
    number // flow type is ? but should be (Number & Comparable)
  }
}

Issue Links

• is related to: GROOVY-7971 @CS flow typing incorrectly casting to map at runtime
• is related to: GROOVY-8965 instanceof with || inserts wrong cast
• is related to: GROOVY-9769 STC: UnionTypeClassNode created for simple instanceof scenarios
• is related to: GROOVY-9320 Support serializable lambda expression
• is related to: GROOVY-7333 Incorrect inferred type in instanceof check of array