Can't suppress NRT warnings on ternary with refs

[MihaZupan]

Version Used:

SDK 9.0.100-preview.6.24303.15

Steps to Reproduce:

While you can suppress NRT warnings on simple assignments like so

ref object myRef = ref GetNullableObjectRef()!;
ref object? myRef = ref GetObjectRef()!;

I've been unable to find a combination of !/?/() to suppress the warnings on this ternary:

void Problem(bool condition)
{
    ref object myRef = ref (condition
        ? ref GetObjectRef()!
        : ref GetNullableObjectRef()!)!;

    // Assuming these are methods whose shape I can't change
    static ref object GetObjectRef() => ref Unsafe.NullRef<object>();
    static ref object? GetNullableObjectRef() => ref Unsafe.NullRef<object?>();
}

SharpLab

Diagnostic Id:

warning CS8619: Nullability of reference types in value of type 'object' doesn't match target type 'object?'.

Expected Behavior:

I should be able to suppress warnings with some combination of !s.

Actual Behavior:

I can only avoid warnings via #nullable disable.

[TessenR]

@jjonescz Is it expected that now you can suppress nullability mismatch for foreach with ref variables but not for foreach with regular variables?

It looks like the following test is supposed to cover that scenario, but it's missing the actual nullability mismatch because the parameter of the test method is object[] instead of object?[]

9941c1f#diff-14fe026e6093e9522c01e6c377b26554dd6b663214884198dcc244f370548fa1R90883

The following code right now does have a warning and it cannot be suppressed:

void M2(object[] a) { foreach (object item in a!) { } }

Should I create a separate issue for this case?

[jjonescz]

@TessenR that indeed looks unexpected, I've converted your comment into an issue: #75430. Thanks for reporting this.