Proposed exception to SA1312

[lcsondes]

Names such as _, __, etc. are commonly used to indicate that they're otherwise ignored, which is now "official" syntax in some instances such as out _.

There are cases where you want to evaluate an expression for its side effects, but are otherwise uninterested in the results, this would be written as var _ = expression;. It's also a relatively common convention to use (_, __) => blah for a lambda that's used as an event handler (sender, args) if you don't want to use the delegate{blah} syntax for ignoring arguments.

I'd like to propose names that are made up of only underscores to not trigger SA1312.

[sharwell]

There are cases where you want to evaluate an expression for its side effects, but are otherwise uninterested in the results, this would be written as var _ = expression;.

The new discard form for these is:

_ = expression;

The discard syntax does not trigger SA1312, and can be used any number of times within the same method.

It's also a relatively common convention to use (_, __) => blah for a lambda that's used as an event handler (sender, args) if you don't want to use the delegate{blah} syntax for ignoring arguments.

This is SA1313, and covered by previous issue #1606.

[lcsondes]

I did not know that, suggestion withdrawn.

[colgreen]

The exception doesn't seem to be working in this case:

await foreach (var _ in sut.GetListAsync()) { }

(seen in a unit test that was exhausting an IAsyncEnumerable without using the enumerated items.)

In this case I just changed it to use a normal variable name <shrugs> :)