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@tmat I see you have added a workaround. Are you aware of any downstream callers of this API (like Roslyn) who might be impacted by this?

Did you want to suggest a fix?

I see you have added a workaround. Are you aware of any downstream callers of this API (like Roslyn) who might be impacted by this?

I'm not aware of any. Not high priority to fix. Would be nice to remove the workaround.

Did you want to suggest a fix?

The line referenced above needs to be updated to no accumulate. Then some comments and tests need to be updated.
Should be easy to do.

Hello, I am trying to read this thread and hope to understand it so that I could start contributing this as my first task.
I guess I will need a bit of guidance, though.
I am not sure if I got what the recently added workaround should be replaced with.

Can you elaborate on The line referenced above needs to be updated to no accumulate.?
Do you mean something like guidSizes[r + 1] = deltaReaders[r].GetHeapSize(HeapIndex.Guid) / guidSize;?

When #Guid heap is emitted in delta metadata the compiler first writes N empty guids in the heap. where N is number of Guids in all previous generations including the baseline DLL, and then writes guids used in the delta.

Like so:

Baseline DLL: {Guid 1} ... {Guid N0}
Generation 1 delta: {empty guid} ... {empty guid} {Guid N0+1} ... {Guid N0 + N1}
Generation 2 delta: {empty guid} ... {empty guid} {empty guid} ... {empty guid} {Guid N0+N1+1} ... {Guid N0 + N1 + N2}

This is therefore not correct:

guidSizes[r + 1] = guidSizes[r] + deltaReaders[r].GetHeapSize(HeapIndex.Guid) / guidSize;

guidSizes[r] shouldn't be added to guidSizes[r+1].

Instead the size of Guid heap in generation r is simply: deltaReaders[r].GetHeapSize(HeapIndex.Guid) / guidSize;

I just opened this:
#115268
Let me know if it could be fine