C# 7.x 15.15.1 standard library task types

[KalleOlaviNiemitalo]

Describe the bug

In the C# 7 draft, 15.15.1 says

(The Standard library types System.Threading.Tasks.Task<T> and types constructed from System.Threading.Tasks.Task are task types.)

However, there cannot be any types constructed from System.Threading.Tasks.Task, because it is not a generic type.

Example

None

Expected behavior

(The Standard library type System.Threading.Tasks.Task and types constructed from System.Threading.Tasks.Task<T> are task types.)

Additional context

Could also mention ValueTask and ValueTask<T>, which are listed in C.3 (Standard Library Types not defined in ISO/IEC 23271).

C.3 is inconsistent on whether the type parameter of these is named T or TResult. This name is not used when referencing the type in C#, but it is stored in the ECMA-335 GenericParam table and may be readable by reflection.

[jskeet]

Hmm... it's interesting that we mention ValueTask at all. The only references are in basic concepts (where we say it doesn't count for a return type in async entry points) and in the standard library. I think I'll leave that inconsistency for now, but fix the generic issue and make it Task<TResult> everywhere.

[KalleOlaviNiemitalo]

ValueTask and ValueTask<TResult> will be needed in C# 8 async streams #606: IAsyncDisposable has a method ValueTask DisposeAsync();, and IAsyncEnumerator<out T> has a method ValueTask<bool> MoveNextAsync();. I don't think C# 7 requiring ValueTask and ValueTask<TResult> would be too much of a burden to implementors.