C# Runtime check fails on compilation

[DanielMSchmidt]

Describe the bug

The CDKTF library does not build with 1.67.0 after upgrading from 1.65.0 in C#. There is an error thrown when running dotnet build --force --configuration Release as part of jsii-pacmak as part of jsii-srcmak.

Expected Behavior

The unchanged code should still build.

Current Behavior

[jsii-pacmak] [WARN] Exception occurred, not cleaning up /var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-packP6yknl
[jsii-pacmak] [WARN] dotnet failed
Error: All attempts failed. Last error: Command (dotnet build --force --configuration Release) failed with status 1:

/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp/Cdktf/ListTerraformIterator.cs(33,26): error CS8120: The switch case is unreachable. It has already been handled by a previous case or it is impossible to match. [/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp.Cdktf.csproj]
/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp/Cdktf/ListTerraformIterator.cs(35,26): error CS8120: The switch case is unreachable. It has already been handled by a previous case or it is impossible to match. [/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp.Cdktf.csproj]
/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp/Cdktf/ListTerraformIterator.cs(37,26): error CS8120: The switch case is unreachable. It has already been handled by a previous case or it is impossible to match. [/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp.Cdktf.csproj]
/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp/Cdktf/ListTerraformIterator.cs(39,26): error CS8120: The switch case is unreachable. It has already been handled by a previous case or it is impossible to match. [/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp.Cdktf.csproj]
/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp/Cdktf/ListTerraformIterator.cs(41,26): error CS8120: The switch case is unreachable. It has already been handled by a previous case or it is impossible to match. [/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp.Cdktf.csproj]
/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp/Cdktf/TerraformIterator.cs(57,26): error CS8120: The switch case is unreachable. It has already been handled by a previous case or it is impossible to match. [/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp.Cdktf.csproj]
/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp/Cdktf/TerraformIterator.cs(59,26): error CS8120: The switch case is unreachable. It has already been handled by a previous case or it is impossible to match. [/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp.Cdktf.csproj]
/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp/Cdktf/TerraformIterator.cs(61,26): error CS8120: The switch case is unreachable. It has already been handled by a previous case or it is impossible to match. [/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp.Cdktf.csproj]
/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp/Cdktf/TerraformIterator.cs(63,26): error CS8120: The switch case is unreachable. It has already been handled by a previous case or it is impossible to match. [/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp.Cdktf.csproj]
/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp/Cdktf/TerraformIterator.cs(65,26): error CS8120: The switch case is unreachable. It has already been handled by a previous case or it is impossible to match. [/private/var/folders/z_/v03l33d55fb57nrr3b1q03ch0000gq/T/npm-pack9gX9b6/HashiCorp.Cdktf/HashiCorp.Cdktf.csproj]

The code in question looks like this in C#:

public class ListTerraformIterator : HashiCorp.Cdktf.TerraformIterator
    {
        /// <remarks>
        /// <strong>Stability</strong>: Experimental
        /// </remarks>
        public ListTerraformIterator(object list): base(_MakeDeputyProps(list))
        {
        }

        [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]
        private static DeputyProps _MakeDeputyProps(object list)
        {
            if (Amazon.JSII.Runtime.Configuration.RuntimeTypeChecking)
            {
                switch (list)
                {
                    case string[] cast_a33039:
                        break;
                    case HashiCorp.Cdktf.IResolvable cast_a33039:
                        break;
                    case double[] cast_a33039:
                        break;
                    case HashiCorp.Cdktf.ComplexList cast_a33039:
                        break;
                    case HashiCorp.Cdktf.StringMapList cast_a33039:
                        break;
                    case HashiCorp.Cdktf.NumberMapList cast_a33039:
                        break;
                    case HashiCorp.Cdktf.BooleanMapList cast_a33039:
                        break;
                    case HashiCorp.Cdktf.AnyMapList cast_a33039:
                        break;
                    case object[] cast_a33039:
                        for (var __idx_14fecf = 0 ; __idx_14fecf < cast_a33039.Length ; __idx_14fecf++)
                        {
                            switch (cast_a33039[__idx_14fecf])
                            {
                                case bool cast_30b700:
                                    break;
                                case HashiCorp.Cdktf.IResolvable cast_30b700:
                                    break;
                                case Amazon.JSII.Runtime.Deputy.AnonymousObject cast_30b700:
                                    // Not enough information to type-check...
                                    break;
                                case null:
                                    throw new System.ArgumentException($"Expected argument {nameof(list)}[{__idx_14fecf}] to be one of: bool, {typeof(HashiCorp.Cdktf.IResolvable).FullName}; received null", nameof(list));
                                default:
                                    throw new System.ArgumentException($"Expected argument {nameof(list)}[{__idx_14fecf}] to be one of: bool, {typeof(HashiCorp.Cdktf.IResolvable).FullName}; received {cast_a33039[__idx_14fecf].GetType().FullName}", nameof(list));
                            }
                        }
                        break;
                    case Amazon.JSII.Runtime.Deputy.AnonymousObject cast_a33039:
                        // Not enough information to type-check...
                        break;
                    case null:
                        throw new System.ArgumentException($"Expected argument {nameof(list)} to be one of: string[], {typeof(HashiCorp.Cdktf.IResolvable).FullName}, double[], {typeof(HashiCorp.Cdktf.ComplexList).FullName}, {typeof(HashiCorp.Cdktf.StringMapList).FullName}, {typeof(HashiCorp.Cdktf.NumberMapList).FullName}, {typeof(HashiCorp.Cdktf.BooleanMapList).FullName}, {typeof(HashiCorp.Cdktf.AnyMapList).FullName}, object[]; received null", nameof(list));
                    default:
                        throw new System.ArgumentException($"Expected argument {nameof(list)} to be one of: string[], {typeof(HashiCorp.Cdktf.IResolvable).FullName}, double[], {typeof(HashiCorp.Cdktf.ComplexList).FullName}, {typeof(HashiCorp.Cdktf.StringMapList).FullName}, {typeof(HashiCorp.Cdktf.NumberMapList).FullName}, {typeof(HashiCorp.Cdktf.BooleanMapList).FullName}, {typeof(HashiCorp.Cdktf.AnyMapList).FullName}, object[]; received {list.GetType().FullName}", nameof(list));
                }
            }
            return new DeputyProps(new object?[]{list});
        }

The errors are thrown from case HashiCorp.Cdktf.ComplexList cast_a33039: to case HashiCorp.Cdktf.AnyMapList cast_a33039:.

Reproduction Steps

git clone [email protected]:hashicorp/terraform-cdk.git
cd terraform-cdk
git checkout automation/yarn-upgrade
yarn
yarn build
yarn package 

Possible Solution

No response

Additional Information/Context

No response

SDK version used

1.57.0

Environment details (OS name and version, etc.)

OSX 12.6

[RomainMuller]

Thanks for reporting. I can confirm that, contrary to the unwritten assumption, types in a union aren't necessarily unrelated... and this may cause us to emit unnecessary checks.

Should not be all too hard to either remove checks that are implied by others, or to re-order the clauses so that the implied clauses come first (I lean towards removing redundant clauses but am wondering if there'd be any associated risk/tradeoff)

[github-actions]

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