Async main doc

docs/features/async-main.md

@@ -0,0 +1,12 @@
+# Async Task Main
+## [dotnet/csharplang proposal](https://github.com/dotnet/csharplang/blob/master/proposals/async-main.md)
+
+## Technical Details
+
+* The compiler must recognize `Task` and `Task<int>` as valid entrypoint return types in addition to `void` and `int`.
+* The compiler must allow `async` to be placed on a main method that returns a `Task` or a `Task<T>` (but not void).
+* The compiler must generate a shim method `$EntrypointMain` that mimics the arguments of the user-defined main.
+  * `static async Task Main(...)` -> `static void $EntrypointMain(...)`
+  * `static async Task<int> Main(...)` -> `static int $EntrypointMain(...)`
+  * The parameters between the user-defined main and the generated main should match exactly.
+* The body of the generated main should be `return Main(args...).GetAwaiter().GetResult();`

docs/features/async-main.test.md

@@ -0,0 +1,56 @@
+Main areas to test:
+* Signature acceptance / rejection
+* Method body creation
+
+# Signature acceptance / rejection
+
+## Single Mains
+Classes that contain only a single "main" method
+
+### Single legal main
+* Past: Ok
+* New 7: Ok
+* New 7.1 Ok
+
+### Single async (void) main
+* Past: ERR (Async can't be main)
+* New 7: ERR (Update to get this to work)
+* New 7.1: Ok
+
+### Single async (Task) main
+* Past: ERR (No entrypoints found), WARN (has the wrong signature to be an entry point)
+* New 7: ERR (Update to get this to work)
+* New 7.1 Ok
+
+### Single async (Task<int>) main
+* Past: ERR (No entrypoints found), WARN (has the wrong signature)
+* New 7: ERR (Update to get this to work)
+* New 7.1: Ok
+
+## Multiple Mains
+Classes that contain more than one main
+
+### Multiple legal mains
+* Past: Err
+* New 7: Err
+* New 7.1: Err
+
+### Single legal main, single async (void) main
+* Past: Err (an entrypoint cannot be marked with async)
+* New 7: Err (new error here?)
+* New 7.1: Err (new error here? "void is not an acceptable async return type")
+
+### Single legal main, single legal Task main
+* Past: Ok (warning: task main has wrong signature)
+* New 7: Ok (new warning here)
+* New 7.1: Ok (new warning here?)
+
+### Single legal main, single legal Task<int> main
+* Past: Ok (warning: task main has wrong signature)
+* New 7: Ok (new warning here)
+* New 7.1: Ok (new warning here?)
+
+# Method body creation
+
+* Inspect IL for correct codegen.
+* Make sure that attributes are correctly applied to the synthesized mains.