SA1008 is returned for collection expressions containing multi-argument lambda.

[TheBrambleShark]

I'm recreating the MultiValueDictionary type and part of that means recreating tests.

I'm working with a test for the Add(TKey, TValue) function, here:

https://github.com/dotnet/corefxlab/blob/archive/tests/Microsoft.Experimental.Collections.Tests/Microsoft/Collections/Extensions/MultiValueDictionaryTests.cs#L577-L582

private AddDelegate<TKey, TValue>[] Add<TKey, TValue>()
    {
        var ret = new AddDelegate<TKey, TValue>[1];
        ret[0] = (MultiValueDictionary<TKey, TValue> mvd, TKey key, TValue value) => mvd.Add(key, value);
        return ret;
    }

When I try to rebuild this method, I am using this code:

private static AddDelegate<TKey, TValue>[] Add<TKey, TValue>()
    where TKey : notnull
    => [(mvd, key, value) => mvd.Add(key, value)];
        ^ SA1008 Openening parenthesis should be preceded by a space.

If I follow its advice and provide a space, then I get a different error.

=> [ (mvd, key, value) => mvd.Add(key, value)];
   ^ SA1010 Opening square brackets should not be followed by a space.

[bjornhellander]

This triggers in unit tests on master as well, so it seems to be a "new" false positive.