63 lines
1.8 KiB
Markdown
63 lines
1.8 KiB
Markdown
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# C# Language Design Meeting for Jan 23, 2019
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## Agenda
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Function pointers ([Updated proposal](https://github.com/dotnet/csharplang/blob/master/proposals/function-pointers.md))
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## Discussion
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### Creation of a function pointer to a managed method
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The proposal is `&Class.Method` to produce a function pointer. The question
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is whether `&Class.Method` is target-typed, whether it has a natural type
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when there's only one member in the method group, or both.
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Target-typing is useful because, like with delegates, it allows you to select
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a unique method out of a method group with multiple incompatible overloads.
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Natural type is useful because it allows things like `var` and `void*`.
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**Conclusion**
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Let's start by only doing target-typing. Also, the section "better function
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member" is not necessary without the natural typing.
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### DllImport CallingConvention?
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There is actually a stub that the compiler calls for P/Invoke with DllImport
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that is always done using the managed calling convention, so there's no
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reason for function pointers to use the DllImportAttribute.
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NativeCallback is intended for the scenario where you want to avoid the stub
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overhead.
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### NativeCallableAttribute
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Let's look at this in more detail.
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### Syntax
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```C#
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1. func* managed int(string)
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2. func*(string)->int
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3. func* managed (string)->int
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4. func* managed (string)=>int
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5. managed int(string)*
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5a. int(string)*
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6. managed int(string)
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7. managed (string)->int
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8. delegate* int(string)
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9. func int(string)*
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10. delegate int(string)*
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```
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**Conclusion**
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We're not sure about all the potential ambiguities here. Let's look at (5a),
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possibly disambiguating with the calling convention.
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### Things to clarify in spec
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* What does the CLR do if you try to call a method that has a modreq/modopt in
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the signature, but the `calli` has the signature without the modreq/modopt? |