ECJ Relevant JDK Issues

Collection of bugs in the OpenJDK bug tracker that are affecting compatibility between ecj - JLS - javac.

Wildcards and captures

• Widening of capture vars occurs at unspecified times
  • https://bugs.openjdk.org/browse/JDK-8016207 (since 2013)
• Inference: define supertype parameterization for wildcard-parameterized types
  • https://bugs.openjdk.org/browse/JDK-8016196 (since 2013)
  • used as an excuse for a test from #4315
• 18.4: Clean up resolution of capture ivars
  • https://bugs.openjdk.org/browse/JDK-8054721 (since 2014)
• skip capture conversion before subtyping if types are parameterizations of the same class or interface
  • https://bugs.openjdk.org/browse/JDK-8160244 (since 2016)
• Incorrect treatment of wildcards in subtyping
  • https://bugs.openjdk.org/browse/JDK-8164401 (since 2016) ❌ javac accepts, throws at runtime ✔️ ecj rejects
• type inference: javac is incorrectly applying capture conversion during incorporation
  • https://bugs.openjdk.org/browse/JDK-8206142 (since 2018) ❌ javac rejects ✔️ ecj accepts
• skip capture conversion before subtyping if types are parameterizations of the same class or interface
  • https://bugs.openjdk.org/browse/JDK-8160244 (since 2016) ❌ javac rejects ✔️ ecj accepts

With examples where ecj and javac are congruent:

• 18.2.1: Capture variables should not escape lambda bodies
  • https://bugs.openjdk.org/browse/JDK-8170887 (since 2016)
• Lower bound containing wildcard get lost during type inference
  • https://bugs.openjdk.org/browse/JDK-8251891 (since 2020)

Intersection types

• 4.9: Clarify membership of intersection types for wildcard parameterizations
  • https://bugs.openjdk.org/browse/JDK-7034922 (since 2011)
• GLB ignores different parameterizations of the same type
  • https://bugs.openjdk.org/browse/JDK-8043374 (since 2014) both compilers questionable - in different ways