AnnotatedTypeMirrors aren't structurally equal.

[cushon]

This crash reproduces at head, after the fix for #4829

The issue only reproduces with the class for L is on the classpath, rather than compiled from source.

abstract class L {

  public static L g() {
    throw new AssertionError();
  }

  public final <F1> C<F1> n(F<F1> field1) {
    throw new AssertionError();
  }
}

abstract class C<F1> extends D<Long, C<F1>> {}

abstract class D<V, M extends D<V, M>> extends G<V, M> {}

abstract class G<V, M extends G<V, M>> {
  abstract M e();
}

final class F<T> {
  public static <E extends Enum<E>> F<E> of(Class<E> e) {
    throw new AssertionError();
  }
}

public class N {

  enum E {}

  C<E> c = L.g().n(F.of(E.class)).e();
}

javac L.java && ./checker/bin/javac -processor Nullness N.java
...
error: AnnotatedTypeMirrors aren't structurally equal.
    type1 = AnnotatedTypeVariable( capture#342 extends Object )
    type2 = AnnotatedDeclaredType( E )
    visitHistory = org.checkerframework.framework.type.StructuralEqualityVisitHistory@11f8d64
  ; The Checker Framework crashed.  Please report the crash.
  Compilation unit: N.java
  Last visited tree at line 5 column 3:
    C<E> c = L.g().n(F.of(E.class)).e();
  Exception: java.lang.Throwable; java.lang.Throwable
        at org.checkerframework.javacutil.BugInCF.<init>(BugInCF.java:22)
        at org.checkerframework.framework.type.visitor.AbstractAtmComboVisitor.defaultAction(AbstractAtmComboVisitor.java:52)
        at org.checkerframework.framework.type.StructuralEqualityComparer.defaultAction(StructuralEqualityComparer.java:56)
        at org.checkerframework.framework.type.StructuralEqualityComparer.defaultAction(StructuralEqualityComparer.java:29)
        at org.checkerframework.framework.type.visitor.AbstractAtmComboVisitor.visitTypevar_Declared(AbstractAtmComboVisitor.java:543)
        at org.checkerframework.framework.util.AtmCombo.accept(AtmCombo.java:587)
        at org.checkerframework.framework.type.StructuralEqualityComparer.areEqual(StructuralEqualityComparer.java:93)
        at org.checkerframework.framework.type.StructuralEqualityComparer.areEqualInHierarchy(StructuralEqualityComparer.java:105)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.areEqualInHierarchy(DefaultTypeHierarchy.java:228)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.isContainedBy(DefaultTypeHierarchy.java:303)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.isContainedMany(DefaultTypeHierarchy.java:529)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.visitTypeArgs(DefaultTypeHierarchy.java:499)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.visitDeclared_Declared(DefaultTypeHierarchy.java:445)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.visitDeclared_Declared(DefaultTypeHierarchy.java:45)
        at org.checkerframework.framework.util.AtmCombo.accept(AtmCombo.java:311)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.isSubtype(DefaultTypeHierarchy.java:147)
        at org.checkerframework.checker.nullness.KeyForAnnotatedTypeFactory$KeyForTypeHierarchy.isSubtype(KeyForAnnotatedTypeFactory.java:152)
        at org.checkerframework.framework.type.DefaultTypeHierarchy.isSubtype(DefaultTypeHierarchy.java:123)
        at org.checkerframework.common.basetype.BaseTypeVisitor.commonAssignmentCheck(BaseTypeVisitor.java:2784)
        at org.checkerframework.common.basetype.BaseTypeVisitor.commonAssignmentCheck(BaseTypeVisitor.java:2761)
        at org.checkerframework.common.basetype.BaseTypeVisitor.commonAssignmentCheck(BaseTypeVisitor.java:2721)
        at org.checkerframework.common.basetype.BaseTypeVisitor.visitVariable(BaseTypeVisitor.java:1459)
        at org.checkerframework.common.basetype.BaseTypeVisitor.visitVariable(BaseTypeVisitor.java:190)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:974)
        at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
        at org.checkerframework.framework.source.SourceVisitor.scan(SourceVisitor.java:88)
        at org.checkerframework.common.basetype.BaseTypeVisitor.scan(BaseTypeVisitor.java:356)
        at org.checkerframework.common.basetype.BaseTypeVisitor.scan(BaseTypeVisitor.java:190)
        at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
        at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
        at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:113)
        at jdk.compiler/com.sun.source.util.TreeScanner.visitClass(TreeScanner.java:187)
        at org.checkerframework.framework.source.SourceVisitor.visitClass(SourceVisitor.java:94)
        at org.checkerframework.common.basetype.BaseTypeVisitor.processClassTree(BaseTypeVisitor.java:556)
        at org.checkerframework.common.basetype.BaseTypeVisitor.visitClass(BaseTypeVisitor.java:498)
        at org.checkerframework.common.basetype.BaseTypeVisitor.visitClass(BaseTypeVisitor.java:190)
        at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:808)
        at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:56)
        at org.checkerframework.framework.source.SourceVisitor.visit(SourceVisitor.java:82)
        at org.checkerframework.framework.source.SourceChecker.typeProcess(SourceChecker.java:984)
        at org.checkerframework.common.basetype.BaseTypeChecker.typeProcess(BaseTypeChecker.java:542)
        at org.checkerframework.common.basetype.BaseTypeChecker.typeProcess(BaseTypeChecker.java:535)
        at org.checkerframework.javacutil.AbstractTypeProcessor$AttributionTaskListener.finished(AbstractTypeProcessor.java:188)
        at jdk.compiler/com.sun.tools.javac.api.ClientCodeWrapper$WrappedTaskListener.finished(ClientCodeWrapper.java:828)
        at jdk.compiler/com.sun.tools.javac.api.MultiTaskListener.finished(MultiTaskListener.java:132)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1419)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1376)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:972)
        at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:311)
        at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:170)
        at jdk.compiler/com.sun.tools.javac.Main.compile(Main.java:57)
        at jdk.compiler/com.sun.tools.javac.Main.main(Main.java:43)
error: AnnotatedTypeMirrors aren't structurally equal.

[cushon]

I minimized it a little more:

abstract class C<F1> extends G<C<F1>> {}

abstract class G<M extends G<M>> {
  abstract M e();
}

abstract class N {
  enum E {}
  abstract <F1> C<F1> n(F<F1> field1);
  abstract <E extends Enum<E>> F<E> of(Class<E> e);
  C<E> c = n(of(E.class)).e();
}