Allow local class creation in early construction context

[mcimadamore]

Some time ago, I added a restriction to reject local class creation in early context. The reason this restriction was added is that capture of "this" in local classes in early context work differently, in the sense that a local class in such context is allowed to capture an outer this, but not the current this.

Example:

class Outer {
    void m() { }
    
    class Inner {
        Inner() {
            class Foo {
                void t() { m(); }
            }
            new Foo();
	    super();
	}
    }
}

This is legal, as the local class needs Outer.this, not Inner.this.

But, the babylon compiler features several restriction when it comes to inner classes and constructors:

1. code reflection in constructors is disabled
2. reflectable program elements in inner/local classes are skipped

Now, (1) seems promising (after all, you only are in early construction context if you are... in a constructor). But, you can still have a reflectable lambda in a constructor:

class Outer {
    void m() { }
    
    class Inner {
        Inner() {
            class Foo {
                void t() { m(); }
            }
            @Reflect
            Runnable r = () -> new Foo();
	    super();
	}
    }
}

Except -- this still fails, beause of (2) -- the reflectable lambda is inside an inner class (Inner).

For these reasons, I don't think it's possible to ever trigger a case where strange outer this capturing would be relevant. For this to happen the local class has to be inside a constructor of an inner class. And, inside that constructor we can't, by definition, have reflectable elements.

The equivalent example w/o inner classes:

class Outer {
    Outer() {
        class Foo {
            void t() { }
        }
        @Reflect
        Runnable r = () -> new Foo();
        super();
    }   
}

Is still rejected by the current AST check, but in fact there's nothing problematic about this. So this PR re-allows this.

I've added a test to make sure this shape works correctly -- unfortunately I couldn't rely on the @IR test harness (as that requires the reflectable element to be inside a reflectable method, which is not the case here), so I have hand-rolled a new test.

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Reviewers

• Paul Sandoz (@PaulSandoz - Reviewer)

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[mcimadamore]

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[openjdk]

@mcimadamore This change now passes all automated pre-integration checks.

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Allow local class creation in early construction context

Reviewed-by: psandoz

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• c6413aa: Inliner bug

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[mlbridge]

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[PaulSandoz]

Very good. This expands the use of where records can be used in reflectable lambdas.

[mcimadamore]

/integrate

[openjdk]

Going to push as commit 835ba45.
Since your change was applied there has been 1 commit pushed to the code-reflection branch:

• c6413aa: Inliner bug

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[openjdk]

@mcimadamore Pushed as commit 835ba45.

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