That check was added due to: #331

Have you tested your code with the code from that issue?

Seems like the only problem is that it doesn't find the generic parameter in the type/method so it can't print the GP name, only its GP index. It shouldn't be a problem.

The TypeSpec I printed is in instruction read by MethodBodyReader, which is read with gpContext.
https://github.com/0xd4d/dnlib/blob/master/src/Utils/SimpleLazyList.cs#L84
When I resolve TypeSpec without gpContext, 'elem.ContainsGenericParameter' will return false and result will be cached in 'elements[index]'. After that no matter what gpContext I pass to resolve TypeSpec, it will return the cached item but not construct a new one by reading with gpContext.

That check was added due to: #331

Have you tested your code with the code from that issue?

I patched dnSpy's dnlib with this fix and load 'HelloWorld.MaliciousTypeSpecLoop.exe', dnSpy doesn't hang.

updated:
And also test with code:

var m = ModuleDefMD.Load("HelloWorld.MaliciousTypeSpecLoop.exe");
var t = m.ResolveTypeSpec(1).TypeSig;

I think this problem is fixed in ReadTypeDefOrRef(bool allowTypeSpec)
8ea0a56#diff-be44183bc77af09329bfdcdfc484ee0670c3c1b9eff0ef828c2974ede3b409c6R671
I don't know why there is a '!gpContext.IsEmpty'. It seems useless.

Thanks for testing it! Merged.