Record read of ref local even if value is discarded #60910
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| static void F(ref S s) | ||
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| _ = s; |
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Should _ = s; result in a NullReferenceException at runtime if the reference is null?
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From discussion with @jaredpar, we should emit the dereference of ref s here, even though the value is discarded.
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My logic here was essentially that it's possible for a ref to be null hence this is no different than say _ = a.b where b is a field / prop and a is a reference type. It is an operation that has a potential visible side effect of throwing a NullReferenceException.
Before c# 11 there was no supported way in C# to create a ref that points to null which meant this was probably a lower priority issue. I would've felt a bit more ambivalent about it. Now that we can create such ref I feel a bit more confident that we should be treating it as a side effect here.
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Let's emit the dereference as part of the ref fields feature. I've added an item to the ref fields test plan.
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| static void F(ref S s) | ||
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| _ = s.F; |
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Should _ = s.F; result in a NullReferenceException at runtime if s is null?
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@dotnet/roslyn-compiler, please review. |
Fixes #60905