Clarify extern caller unsafe methods #9883
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proposals/unsafe-evolution.md
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| Only `extern` methods which are recognizable from metadata are handled, i.e., methods with the `pinvokeimpl` flag in IL. | ||
| Therefore, `extern` methods without `DllImport` attribute are not recognized as implicitly `unsafe` when used from a different assembly. | ||
| Such `extern` methods exposed as API should not be a common scenario anyway and there is already a warning for `extern` methods without any attribute | ||
| (albeit absence of that warning doesn't guarantee the method will be recognized as `unsafe` in metadata). | ||
| One can mark such methods as `unsafe` explicitly if needed. |
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Why would this be a caveat? The goal is that any extern method is unsafe, period.
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extern without DllImport are not useful anyway I think and we would need to synthesize the RequiresUnsafe attribute for them. Which also means it would be different if such API was compiled by old or new compiler (whereas as currently proposed, even extern apis compiled by old compilers would be recognized in the same way).
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Why would we need to synthesize anything for them? They're extern, they're just always unsafe.
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Why would we need to synthesize anything for them? They're extern, they're just always unsafe.
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Because we can't tell whether they are extern from metadata, that's what I'm trying to say by this PR.
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Extern methods without any attribute look just like plain ordinary empty methods in IL.
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I think you should be able to tell by checking whether the method has IL implementation (method is implemented by IL).
If the method has no implementation in IL and it is not abstract (there may be a few more cases like that), it is extern -> unsafe.
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extern without DllImport are not useful anyway
extern without DllImport are used by https://learn.microsoft.com/en-us/dotnet/api/system.runtime.compilerservices.unsafeaccessorattribute
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You're right, it seems we can recognize extern methods by them having RVA 0, thanks.
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Not sure what to do with this: object.GetType (and probably other methods) on .net framework is marked as extern, so it would be an error to use it outside unsafe under the new rules.
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