Add LDM notes for Jan 23, 2019

meetings/2019/LDM-2019-01-23.md

@@ -0,0 +1,63 @@
+
+# C# Language Design Meeting for Jan 23, 2019
+
+## Agenda
+
+ Function pointers ([Updated proposal](https://github.com/dotnet/csharplang/blob/master/proposals/function-pointers.md))
+
+## Discussion
+
+### Creation of a function pointer to a managed method
+
+The proposal is `&Class.Method` to produce a function pointer. The question
+is whether `&Class.Method` is target-typed, whether it has a natural type
+when there's only one member in the method group, or both.
+
+Target-typing is useful because, like with delegates, it allows you to select
+a unique method out of a method group with multiple incompatible overloads.
+
+Natural type is useful because it allows things like `var` and `void*`.
+
+**Conclusion**
+
+Let's start by only doing target-typing. Also, the section "better function
+member" is not necessary without the natural typing.
+
+### DllImport CallingConvention?
+
+There is actually a stub that the compiler calls for P/Invoke with DllImport
+that is always done using the managed calling convention, so there's no
+reason for function pointers to use the DllImportAttribute.
+
+NativeCallback is intended for the scenario where you want to avoid the stub
+overhead.
+
+### NativeCallableAttribute
+
+Let's look at this in more detail.
+
+### Syntax
+
+```C#
+1. func* managed int(string)
+2. func*(string)->int
+3. func* managed (string)->int
+4. func* managed (string)=>int
+5. managed int(string)*
+   5a. int(string)*
+6. managed int(string)
+7. managed (string)->int
+8. delegate* int(string)
+9. func int(string)*
+10. delegate int(string)*
+```
+
+**Conclusion**
+
+We're not sure about all the potential ambiguities here. Let's look at (5a),
+possibly disambiguating with the calling convention.
+
+### Things to clarify in spec
+
+* What does the CLR do if you try to call a method that has a modreq/modopt in
+  the signature, but the `calli` has the signature without the modreq/modopt?

meetings/2019/README.md

@@ -22,15 +22,16 @@
 
 ## Feb 11, 2019
 
-## Jan 23, 2019
-
-- Function pointers (Jared, Alexandre)
-- Any urgent outstanding topics before two week break
-
 # C# Language Design Notes for 2019
 
 Overview of meetings and agendas for 2019
 
+## Jan 23, 2019
+
+[C# Language Design Notes for Jan 23, 2019](LDM-2019-01-23.md)
+
+Function pointers ([Updated proposal](https://github.com/dotnet/csharplang/blob/master/proposals/function-pointers.md))
+
 ## Jan 16, 2019
 
 [C# Language Design Notes for Jan 16, 2019](LDM-2019-01-16.md)