New generics: specialise a subclass's superclasses without rewriting the list in place

[Frotty]

Problem

The compiler crashed with a ConcurrentModificationException in EliminateGenerics.adaptSubmethods on Jass, the interpreter and Lua. It happened when a method of a generic class was overridden again in a plain subclass and called through a non-generic base:

class Base
    function m() returns int
        return 1
class C<T:> extends Base
    override function m() returns int
        return 2
class D extends C<int>
    override function m() returns int
        return 4
function viaBase(Base b) returns int
    return b.m()

adaptSubmethods rewrote D's superclass list in place with replaceAll(specializeType). Specialising C<int> runs the trigger registered on C. That trigger specialises C.m and adapts its submethods, D.m among them, so it rewrites D's list again inside the outer replaceAll.

The same in-place rewrite existed in two other places:

• specializeClass, for a generic class's own superclasses.
• rewriteRuntimeTypeSuperEdges, which rewrites every class's list in place.

Change

A new helper, specializeSuperClasses, reads a class's superclass list from a copy and replaces the list rather than rewriting it in place. All three callers now use it:

• adaptSubmethods
• specializeClass
• the use queued for each non-generic class, which already built a new list but iterated the live one

The InterfaceTranslator note named this crash as one reason the bridge skips generic classes. I removed that clause; the other reason still stands.

Checks

• Two new tests in GenericsWithTypeclassesTests: the plain subclass, and a subclass that also implements an interface. Both run on Jass, the interpreter and Lua. Both failed with the exception before this change and pass after it.
• These 12 test classes pass (972 tests): GenericsWithTypeclassesTests, GenericsTests, ClassesTests, InterfaceTests, LuaBackendAuditTests, DeterministicChecks, FieldIterationTests, LuaKeyedMapTests, TreeShakerTests, LuaTranslationTests, BugTests, NewFeatureTests.
• Castle fight and zombie defense, built with -lua -inline -localOptimizations, produce Lua byte-identical to master. Zombie defense differs only in its embedded build minute.

Not in this PR

The interface bridge from #1421 is still limited to non-generic classes. Extending it to generic classes is a separate change.

[Frotty]

@codex review

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-09T19:26:08.422725Z	af5f4a1	Manual request

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[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Another round soon, please!

Reviewed commit: af5f4a1cc1

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