[seidewitz]

This PR fixes a bug that causes a StackOverflowError when a metaclass/metadata definition is annotated with itself.

Issue

A self-referential metadata applications such as this one in KerML:

metaclass M {
    metadata M;
}

or this one in SysML:

metadata def M {
    metadata M;
}

result in a StackOverflowError during validation.

Cause

The method TypeAdapter.getBaseTypes is called during implied specialization processing for a Type. It checks all the metadata annotations of a type (if any). If it finds any semantic metadata, it returns the appropriate baseTypes to be specialized.

Method TypeAdapter.getBaseTypes previously made a call on getMetaclass for each metadata feature it checked. This call was added in PR #744 (ST6RI-923 Problem with name resolution when using Semantic metadata). The returned type from this call is not actually used; the reason for the call is just to ensure the proxies are resolved and the metaclass type is available.

The delegate implementing getMetaclass calls FeatureUtil.getFirstTypeOf, which leads to the following call chain:

• FeatureUtil.getFirstTypeOf
  • FeatureUtil.getAllTypesOf
    • FeatureAdapter.getAllTypes
      • FeatureAdapter.getTypes
      • FeatureAdapter.removeRedundantTypes

When there is a self-referential annotation, as in the examples above, recursion leading to the stack overflow happens through removeRedundantTypes, while looking for other supertypes of the metaclass/metadata def.

Changes

Replaced the getMetaclass call in getBaseTypes with a call to FeatureUtil.getTypesOf, which provides access to the lower-level method FeatureAdapter.getTypes. By avoiding calling removeRedundantTypes, this resolves the stack overflow issue, while preserving the fix of PR #744.

[seidewitz]

@vincemolnar
Please review this PR as soon as possible so it can be included in the 2026-09 release.

[seidewitz]

@vincemolnar
Please review this PR by Tuesday morning (20 Oct), Eastern Time.

[vincemolnar]

I have confirmed that the fixes prevent the stack overflow for all the previously identified examples.