LDM Notes for December 4th, 2024

[333fred]

https://github.com/dotnet/csharplang/blob/main/meetings/2024/LDM-2024-12-04.md

Agenda:

• First-class span open questions
  • Preferring ReadOnlySpan<T> over Span<T> conversions
  • Conversions in expression trees

[RenderMichael]

Is there any chance of starting the “covariant array” feature down a depreciation process? The breaks won’t be silent (assignment will fail) and existing defensiveness won’t be broken (myTArray.GetType() == typeof(T[]) will always return true; maybe we can even get an optimization which recognizes this)

[CyrusNajmabadi]

Losing variance would definitely be problematic. Roslyn, as an example, uses it heavily. Without it, returning something that is safe and zero cost today would now incur copies.