Unsafe evolution: use attribute to denote requires-unsafe members

[jjonescz]

Test plan: #81207

[jcouv]

I see we have an open issue related to this: https://github.com/dotnet/csharplang/blob/main/proposals/unsafe-evolution.md#extern-implicitly-unsafe
But this behavior doesn't seem mentioned in the main body of the spec. Let's make sure we capture it (can wait until the open issue is closed) #Closed

[jjonescz]

But this behavior doesn't seem mentioned in the main body of the spec

The extern section says "any extern method is automatically considered requires-unsafe if compiled under the updated memory safety rules (i.e., it gets the RequiresUnsafeAttribute)"

[jcouv]

    object[] unsafeSymbols = ["C.E", "C.add_E", "C.remove_E"];

Should the Extern_Event test be checking extern event with and without [RequiresUnsafe] instead? Currently it is checking with and without unsafe
Comment applies to some other tests too (Extern_Indexer, ...) #Closed

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Refers to: src/Compilers/CSharp/Test/CSharp15/UnsafeEvolutionTests.cs:8175 in cd0ec37. [](commit_id = cd0ec37, deletion_comment = False)

[jcouv]

nit: if I understood correctly, the associated symbol could not have CallerUnsafeMode.Implicit. Consider assertion as such (here and possibly other similar places)

[jcouv]

nit: Any reason we couldn't do simpler change, just adding assertion: Debug.Assert(this.AssociatedSymbol?.CallerUnsafeMode != CallerUnsafeMode.Implicit);

[jcouv]

Spec: As part of the feature we'd allowed unsafe on accessors, but that's no longer the case. It's not blocking since no longer essential to using the feature, but we may want to confirm. #Closed

[jjonescz]

dotnet/csharplang#9991

[jcouv]

            $"Expected {symbol.GetType().Name} '{symbol.ToTestDisplayString()}' {(shouldHaveAttribute ? "or" : "and")} its associated symbol to{(shouldHaveAttribute ? "" : " not")} have the attribute.");

nit: it may be easier to follow with if statement. Then each branch can have a fully completed sentence #Closed

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Refers to: src/Compilers/CSharp/Test/CSharp15/UnsafeEvolutionTests.cs:284 in cd0ec37. [](commit_id = cd0ec37, deletion_comment = False)

[jcouv]

Done with review pass (commit 1)

[jjonescz]

            $"Expected {symbol.GetType().Name} '{symbol.ToTestDisplayString()}' {(shouldHaveAttribute ? "or" : "and")} its associated symbol to{(shouldHaveAttribute ? "" : " not")} have the attribute.");

Maybe I can simplify by having just one conditional interpolation at the beginning.

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In reply to: 3894019832

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Refers to: src/Compilers/CSharp/Test/CSharp15/UnsafeEvolutionTests.cs:284 in cd0ec37. [](commit_id = cd0ec37, deletion_comment = False)

[jcouv]

LGTM Thanks (commit 4)