Enum constants with lambdas are initialized in static initializer block

[FoxSamu]

Consider the following enum:

public enum Test {
    CLASS_RUNNABLE( new SomeRunnable() ),
    FIELD_RUNNABLE( SomeRunnable.INSTANCE ),
    METHOD_RUNNABLE( SomeRunnable.getInstance() ),
    LAMBDA_RUNNABLE( () -> System.out.println( "Hello" ) ),
    MREF_RUNNABLE( SomeRunnable::runInstance );

    public static Runnable runnable;

    Test( Runnable runnable ) {
        this.runnable = runnable;
    }
}

Compiling this with javac and decompiling this with jd-core produces incorrect java code:

public enum Test {
    CLASS_RUNNABLE(new SomeRunnable()),
    FIELD_RUNNABLE(SomeRunnable.INSTANCE),
    METHOD_RUNNABLE(SomeRunnable.getInstance()),
    LAMBDA_RUNNABLE(SomeRunnable.getInstance()),
    MREF_RUNNABLE(SomeRunnable::runInstance);

    static {
        LAMBDA_RUNNABLE = new Test("LAMBDA_RUNNABLE", 3, () -> System.out.println("Hello"));
    }

    public static Runnable runnable;

    Test(Runnable runnable) {
        this.runnable = runnable;
    }
}

This code is semantically incorrect since enum constructors can't be used directly and enum constants (and static final constants in general) can't be assigned twice.

[FoxSamu]

In general, static fields that are initialized with lambdas are initialized in static initializer blocks instead of in fields declarations themselves (which is usually just possible). While this does not necessary produce incorrect code outside of enums, it would be better to move all field initializers to field declarations where possible.

[FoxSamu]

It seems that fields are initialized in static blocks once they reference local variables. In most situations this is not the case. In case of lambdas, the parameters of the lambdas are counted as local variables referenced by the field initialization and the field initializer is not moved to the field declaration.
To fix the issue, during moving field initializers to declarations the searching for local variable references should stop once the SearchLocalVariableReferenceVisitor enters a lambda expression and continue once it exits that expression.