Always make sure we have the right comparer for DocumentIds #53603
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I believe this fixes dotnet#52698, although I don't have a dump for that issue so I'm having to deduce what I think happened based on the stack alone. Unfortunately the stack also has some frames inlined so there's a bit more guessing than usual: The stack shows that we ended up in Comparer.Compare and it threw; the only exception that it throws directly if the thing being compared isn't IComparable. There aren't many uses of ImmutableSortedDictionary in Roslyn, but the one specific one that makes sense to be under GetDocumentState is the one we have inside our TextDocumentStates type. And that one is one where we normally pass in a custom comparer to pass in DocumentIds, so it seems logical that we somehow ended up with a map that didn't have our comparer. It turns out the Empty member we had didn't specify one, so if we started with the Empty member and then added stuff from there, we'd end up with such a map without a comparer. Why didn't we see this right away? Because it turns out we only have a few uses of .Empty, most of which are with source generated files. And even then we often are creating the source generated collections with something else.
tmat
approved these changes
May 21, 2021
|
@jinujoseph Low risk fix for 16.11. Should fix a very peculiar crash @CyrusNajmabadi saw in 16.10, although we haven't seen many hits since. |
ryzngard
approved these changes
May 24, 2021
jasonmalinowski
deleted the
fix-textdocumentstates-potentially-having-no-comparer
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I believe this fixes #52698, although I don't have a dump for that issue so I'm having to deduce what I think happened based on the stack alone. Unfortunately the stack also has some frames inlined so there's a bit more guessing than usual:
The stack shows that we ended up in Comparer.Compare and it threw; the only exception that it throws directly if the thing being compared isn't IComparable. There aren't many uses of ImmutableSortedDictionary in Roslyn, but the one specific one that makes sense to be under GetDocumentState is the one we have inside our TextDocumentStates type. And that one is one where we normally pass in a custom comparer to pass in DocumentIds, so it seems logical that we somehow ended up with a map that didn't have our comparer.
It turns out the Empty member we had didn't specify one, so if we started with the Empty member and then added stuff from there, we'd end up with such a map without a comparer. Why didn't we see this right away? Because it turns out we only have a few uses of .Empty, most of which are with source generated files. And even then we often are creating the source generated collections with something else.