[GROOVY-11471] Assignments in closures can introduce issues in flow typing

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 5.0.0-alpha-10
• Component/s: Static Type Checker

Language

groovy

• Assignee: Eric Milles
• Reporter: Thodoris Sotiropoulos
• Created: 05/Sep/24 14:48
• Updated: 06/Sep/24 17:24
• Resolved: 06/Sep/24 17:24

Description

I have the following program

class Test {
  public static void main(String[] args) {
    def x = 1
    Closure m = null
    if (true) {
      m = {x = ""}
    }
    x = 1
    m()
  }
} 

Actual behavior

The code compiles, but I get ClassCastException at runtime

 Exception in thread "main" org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object '' with class 'java.lang.String' to class 'java.lang.Integer'
        at org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation.castToNumber(DefaultTypeTransformation.java:177)
        at org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation.continueCastOnNumber(DefaultTypeTransformation.java:294)
        at org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation.castToType(DefaultTypeTransformation.java:248)
        at org.codehaus.groovy.vmplugin.v8.IndyInterface.fromCache(IndyInterface.java:336)
        at Test$_main_closure1.doCall(test.groovy:6)
        at Test$_main_closure1.call(test.groovy)
        at Test.main(test.groovy:9)

Expected behavior

The code should have been rejected.

Issue Links

• is related to: GROOVY-11068 VerifyError when using generic container in closure