Add new .NET 9 rules to editorconfig.

Don't enforce all the rules yet, since we are still targeting .NET 6.

Adjust cast to nullable in UnloadCargo.ChooseExitSubCell. Avoid this cast tripping up CA2021 on older NET SDK versions.

.editorconfig

@@ -74,6 +74,10 @@ dotnet_diagnostic.IDE0211.severity = warning
 #csharp_style_prefer_primary_constructors = true
 dotnet_diagnostic.IDE0200.severity = silent # Requires C# 12
 
+# IDE0330 Prefer 'System.Threading.Lock'
+#csharp_prefer_system_threading_lock = true
+dotnet_diagnostic.IDE0330.severity = silent # Requires C# 13
+
 ## Expression-bodied members
 
 # IDE0021 Use expression body for constructors
@@ -298,6 +302,34 @@ dotnet_diagnostic.IDE0240.severity = warning
 # No options
 dotnet_diagnostic.IDE0241.severity = warning
 
+# This option applies to the collection expression rules below
+# .NET 8 defaults to true/when_types_exactly_match, .NET 9+ defaults to when_types_loosely_match
+#dotnet_style_prefer_collection_expression = true
+
+# IDE0300 Use collection expression for array
+# From above, uses dotnet_style_prefer_collection_expression
+dotnet_diagnostic.IDE0300.severity = silent # Requires C# 12
+
+# IDE0301 Use collection expression for empty
+# From above, uses dotnet_style_prefer_collection_expression
+dotnet_diagnostic.IDE0301.severity = silent # Requires C# 12
+
+# IDE0302 Use collection expression for stackalloc
+# From above, uses dotnet_style_prefer_collection_expression
+dotnet_diagnostic.IDE0302.severity = silent # Requires C# 12
+
+# IDE0303 Use collection expression for 'Create()'
+# From above, uses dotnet_style_prefer_collection_expression
+dotnet_diagnostic.IDE0303.severity = silent # Requires C# 12
+
+# IDE0304 Use collection expression for builder
+# From above, uses dotnet_style_prefer_collection_expression
+dotnet_diagnostic.IDE0304.severity = silent # Requires C# 12
+
+# IDE0305 Use collection expression for fluent
+# From above, uses dotnet_style_prefer_collection_expression
+dotnet_diagnostic.IDE0305.severity = silent # Requires C# 12
+
 ## Field preferences
 
 # IDE0044 Add readonly modifier
@@ -337,6 +369,10 @@ dotnet_diagnostic.IDE0250.severity = warning
 #csharp_style_prefer_readonly_struct_member = true
 dotnet_diagnostic.IDE0251.severity = warning
 
+# IDE0320 Make anonymous function static
+#csharp_prefer_static_anonymous_function = true
+dotnet_diagnostic.IDE0320.severity = warning
+
 ## Null-checking preferences
 
 # IDE1005 Use conditional delegate call
@@ -726,6 +762,18 @@ dotnet_diagnostic.CA1417.severity = warning
 # Use 'nameof' in place of string.
 dotnet_diagnostic.CA1507.severity = warning
 
+# Use ArgumentNullException throw helper.
+dotnet_diagnostic.CA1510.severity = suggestion # TODO: Change to warning once using .NET 7 or later.
+
+# Use ArgumentException throw helper.
+dotnet_diagnostic.CA1511.severity = suggestion # TODO: Change to warning once using .NET 7 or later.
+
+# Use ArgumentOutOfRangeException throw helper.
+dotnet_diagnostic.CA1512.severity = suggestion # TODO: Change to warning once using .NET 8 or later.
+
+# Use ObjectDisposedException throw helper.
+dotnet_diagnostic.CA1513.severity = suggestion # TODO: Change to warning once using .NET 7 or later.
+
 # Avoid redundant length argument.
 dotnet_diagnostic.CA1514.severity = suggestion # TODO: Change to warning once using .NET 8 or later.
 
@@ -853,12 +901,21 @@ dotnet_diagnostic.CA1854.severity = suggestion # TODO: Change to warning once us
 # Use Span<T>.Clear() instead of Span<T>.Fill().
 dotnet_diagnostic.CA1855.severity = suggestion # TODO: Change to warning once using .NET 7 or later.
 
+# Incorrect usage of ConstantExpected attribute.
+dotnet_diagnostic.CA1856.severity = suggestion # TODO: Change to warning once using .NET 7 or later.
+
+# The parameter expects a constant for optimal performance.
+dotnet_diagnostic.CA1857.severity = suggestion # TODO: Change to warning once using .NET 7 or later.
+
 # Use StartsWith instead of IndexOf.
 dotnet_diagnostic.CA1858.severity = warning
 
 # Avoid using 'Enumerable.Any()' extension method.
 dotnet_diagnostic.CA1860.severity = warning
 
+# Use 'CompositeFormat'.
+dotnet_diagnostic.CA1863.severity = suggestion # TODO: Change to warning once using .NET 7 or later.
+
 # Prefer the 'IDictionary.TryAdd(TKey, TValue)' method.
 dotnet_diagnostic.CA1864.severity = suggestion # TODO: Change to warning once using .NET 8 or later.
 
@@ -876,6 +933,12 @@ dotnet_diagnostic.CA1869.severity = suggestion # TODO: Change to warning once us
 # Use a cached 'SearchValues' instance.
 dotnet_diagnostic.CA1870.severity = suggestion # TODO: Change to warning once using .NET 8 or later.
 
+# Do not pass a nullable struct to 'ArgumentNullException.ThrowIfNull'.
+dotnet_diagnostic.CA1871.severity = warning
+
+# Prefer 'Convert.ToHexString' and 'Convert.ToHexStringLower' over call chains based on 'BitConverter.ToString'.
+dotnet_diagnostic.CA1872.severity = warning
+
 ### Reliability Rules
 ### https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/reliability-warnings
 
@@ -900,6 +963,12 @@ dotnet_diagnostic.CA2018.severity = warning
 # ThreadStatic fields should not use inline initialization.
 dotnet_diagnostic.CA2019.severity = suggestion # TODO: Change to warning once using .NET 7 or later.
 
+# Don't call Enumerable.Cast<T> or Enumerable.OfType<T> with incompatible types.
+dotnet_diagnostic.CA2021.severity = warning
+
+# Avoid inexact read with Stream.Read.
+dotnet_diagnostic.CA2022.severity = warning
+
 ### Security Rules
 ### https://learn.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/security-warnings
 
@@ -971,6 +1040,9 @@ dotnet_diagnostic.CA2251.severity = warning
 # Ensure ThreadStatic is only used with static fields.
 dotnet_diagnostic.CA2259.severity = suggestion # TODO: Change to warning once using .NET 7 or later.
 
+# Do not pass a non-nullable value to 'ArgumentNullException.ThrowIfNull'.
+dotnet_diagnostic.CA2264.severity = warning
+
 ### Roslynator.Analyzers
 ### https://josefpihrt.github.io/docs/roslynator/analyzers
 

OpenRA.Mods.Common/Activities/UnloadCargo.cs

@@ -55,8 +55,7 @@ namespace OpenRA.Mods.Common.Activities
 
 			return cargo.CurrentAdjacentCells()
 				.Shuffle(self.World.SharedRandom)
-				.Select(c => (c, pos.GetAvailableSubCell(c)))
+				.Select(c => ((CPos Cell, SubCell SubCell)?)(c, pos.GetAvailableSubCell(c)))
-				.Cast<(CPos, SubCell SubCell)?>()
 				.FirstOrDefault(s => s.Value.SubCell != SubCell.Invalid);
 		}