throw expression in null coalescing assignment

[ronnygunawan]

Why is this not allowed?

void F(string? s) {
    s ??= throw new ArgumentNullException(nameof(s));
}

Currently this code gives me an error: CS8115: A throw expression is not allowed in this context.

[theunrepentantgeek]

I'd conjecture it's not allowed because there's nothing assignable specified on the righthand side of the assignment. I'd further suggest this is deliberate, not an oversight.

[bernd5]

But you could write:

using System;

void F(string? s) {
    _ = s ?? throw new ArgumentNullException(nameof(s));
}
F(null);

[333fred]

Duplicate of #2091.