Asserts in ILLink analyzer

[stephentoub]

I don't know how to repro, but I was making some changes in System.Linq.csproj and all of a sudden was presented with a ton of these:

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Issue Details

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I don't know how to repro, but I was making some changes in System.Linq.csproj and all of a sudden was presented with a ton of these:

Author:	stephentoub
Assignees:	-
Labels:	area-Infrastructure-libraries
Milestone:	-

Tagging subscribers to this area: @agocke, @sbomer, @vitek-karas
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Issue Details

---

I don't know how to repro, but I was making some changes in System.Linq.csproj and all of a sudden was presented with a ton of these:

Author:	stephentoub
Assignees:	-
Labels:	untriaged, area-Tools-ILLink
Milestone:	-

[sbomer]

Thanks for reporting. It would be helpful if you could include the code changes you had made at the time of the assert (just the line numbers mentioned in the error should be enough).

• If there's valid C# that can hit this assert, we need to fix the potential analyzer hole
• If this was reached for invalid C# syntax while editing, we need to not fail in those cases

I'll experiment and see if I can find a way to hit this.

[stephentoub]

I was typing pretty fast and I don't know what was there at the time it triggered. Sorry :(

[stephentoub]

If this was reached for invalid C# syntax while editing, we need to not fail in those cases

It very likely was invalid C# syntax; I was typing and editing and most likely in an inconsistent state.

[sbomer]

What's confusing is that this code path should already be handling invalid C#. The assert indicates we were processing an assignment where the LHS was a BinaryOperation. I can't think of valid C# that does this. Code like a | b = 3 doesn't trigger it because there the LHS is an InvalidOperation that we already handle without asserting.

[sbomer]

I found a repro for this - code like a + = 3 has a BinaryOperation on the LHS, but a child of the BinaryOperation is InvalidOperation. Fixing it in #94888.