[GROOVY-11305] STC: support for-each or for-in loop for implicitly-Iterable type

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: Static Type Checker

Language

groovy

• Assignee: Eric Milles
• Reporter: Eric Milles
• Created: 03/Feb/24 15:40
• Updated: 08/Mar/24 20:53

Description

Consider the following:

class C { // implicitly Iterable<String>
  Iterator<String> iterator() {} // sometimes supplied via DGM
}

@TypeChecked
void test(C c) {
  for (string in c) {
    string.toUpperCase()
  }
}

If "@TypeChecked" is removed, this works. STC cannot determine the loop element type – see StaticTypeCheckingVisitor#inferLoopElementType and compare with inferComponentType which runs for spread.

GROOVY-10476 describes the use case in more detail.

Issue Links

• is related to: GROOVY-10712 STC: for-each over Iterator fails to infer element type
• is related to: GROOVY-8133 Static type checking failure for streams and spread operator
• is related to: GROOVY-10476 STC: for-each loop on iterable-like types
• relates to: GROOVY-11335 STC: for loop element type inference with multiple instanceof