javachecker-framework

checker-framework incompatible types in type argument

I have some code like this where I store a map to java threadlocal,

import java.util.*;

class Foo {
  private final ThreadLocal<Map<String, String>> barMap = ThreadLocal.withInitial(HashMap::new);
}

when enabling the nullness check from checkerframework I get

Error: [type.argument.type.incompatible] incompatible types in type argument.
   found   : @Initialized @NonNull Map<@Initialized @NonNull String, @Initialized @NonNull String>
   required: [extends @Initialized @Nullable Object super null]

I don't understand how to resolve this.

Solution

  • This is a known bug in the Checker Framework. You should suppress the warning.

    The Checker Framework currently uses the Java 7 type inference algorithm. Java 8 made a major change to type inference, which requires a re-implementation in the Checker Framework. (The Checker Framework is essentially a compiler in its own right.) That re-implementation is partly done, but has not yet been completed.