Roslyn produces wrong code for huge switch expression

Version Used: .NET Core SDK 3.1.302 .NET 5 RC1

Steps to Reproduce:

Use the following source code:

using System;
public class C {
    public static int M0(int x)
    {
        var b1 = false;
        var b2 = false;
        var b3 = false;
        var b4 = false;
        var b5 = false;
        var b6 = false;
        var b7 = true; // but, if you remove these two variables b7, b8
        var b8 = true; // then everything is ok
        
        return (x, b1, b2, b3, b4, b5, b6, b7, b8) switch
        {
            (1, false, false, false, false, false, false, true, true) => 1,
            _ => -1,
        };
    }
    
    public static void Main() {
        Console.WriteLine(M0(1));
    }
}

It will produce:

using System;
public class C
{
    public static int M0(int x)
    {
        bool flag = false;
        bool flag2 = false;
        bool flag3 = false;
        bool flag4 = false;
        bool flag5 = false;
        bool flag6 = false;
        bool flag7 = true;
        bool flag8 = true;
        bool flag9 = default(bool);   // these vars are not present in source code
        bool flag10 = default(bool);  // they are used instead of the "real" ones
        if (x == 1 && !flag && !flag2 && !flag3 && !flag4 && !flag5 && !flag6 && flag9 && flag10)
        {
            return 1;
        }
        return -1;
    }

    public static void Main()
    {
        Console.WriteLine(M0(1));
    }
}

Expected Behavior: Provided sample should print “1”.

Actual Behavior: Provided sample will print “-1” (wrong code is generated).

[Youssef1313]

Simpler repro:

https://sharplab.io/#v2:EYLgtghgzgLgpgJwDQxAgrgOyQExAagB8ABAJgEYBYAKGIGYACMhgYQYG8aHunHjyAbAwCWmGAwCyABgAUASi492PRTx7EA7AxnkkDXfr0HjRo3IZQA7sJgBjABaq1HJ8547Thrye/mAvAB8hq5uDAD6DIEMALS6IdwAvgDcTglOTmSkLtShTOQAnDLS8nIpOTxp1AlAA===

[RikkiGibson]

Fixed by #48028. Thank you for reporting.