Preventing methods with [Constant] parameters from being passed as re…

…ferences (#924)

src/D2L.CodeStyle.Analyzers/ApiUsage/ConstantAttributeAnalyzer.cs

@@ -1,7 +1,6 @@
 #nullable disable
 
 using System.Collections.Immutable;
-using System.Linq;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
@@ -14,7 +13,8 @@ public sealed class ConstantAttributeAnalyzer : DiagnosticAnalyzer {
 		public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics =>
 			ImmutableArray.Create(
 				Diagnostics.NonConstantPassedToConstantParameter,
-				Diagnostics.InvalidConstantType
+				Diagnostics.InvalidConstantType,
+				Diagnostics.ReferenceToMethodWithConstantParameterNotSupport
 			);
 
 		public override void Initialize( AnalysisContext context ) {
@@ -61,6 +61,15 @@ CompilationStartAnalysisContext context
 				),
 				OperationKind.Conversion
 			);
+
+			context.RegisterOperationAction(
+				ctx => AnalyzeMethodReference(
+					ctx,
+					(IMethodReferenceOperation)ctx.Operation,
+					constantAttribute
+				),
+				OperationKind.MethodReference
+			);
 		}
 
 		private static void AnalyzeParameter(
@@ -168,6 +177,27 @@ INamedTypeSymbol constantAttribute
 			);
 		}
 
+		private static void AnalyzeMethodReference(
+			OperationAnalysisContext context,
+			IMethodReferenceOperation operation,
+			INamedTypeSymbol constantAttribute
+		) {
+
+			foreach( IParameterSymbol parameter in operation.Method.Parameters ) {
+
+				if( !HasAttribute( parameter, constantAttribute ) ) {
+					continue;
+				}
+
+				context.ReportDiagnostic(
+					descriptor: Diagnostics.ReferenceToMethodWithConstantParameterNotSupport,
+					location: operation.Syntax.GetLocation()
+				);
+
+				return;
+			}
+		}
+
 		/// <summary>
 		/// Check if the symbol has a specific attribute attached to it.
 		/// </summary>

src/D2L.CodeStyle.Analyzers/D2L.CodeStyle.Analyzers.csproj

@@ -6,7 +6,7 @@
     <Title>D2L.CodeStyle.Analyzers</Title>
     <Product>D2L.CodeStyle</Product>
     <Description>D2L.CodeStyle analyzers</Description>
-    <Version>0.203.0</Version>
+    <Version>0.204.0</Version>
     <PackageLicenseExpression>Apache-2.0</PackageLicenseExpression>
     <PackageProjectUrl>https://github.com/Brightspace/D2L.CodeStyle</PackageProjectUrl>
     <Authors>D2L</Authors>

src/D2L.CodeStyle.Analyzers/Diagnostics.cs

@@ -757,5 +757,14 @@ public static class Diagnostics {
 			defaultSeverity: DiagnosticSeverity.Error,
 			isEnabledByDefault: true
 		);
+
+		public static readonly DiagnosticDescriptor ReferenceToMethodWithConstantParameterNotSupport = new DiagnosticDescriptor(
+			id: "D2L0102",
+			title: "References to methods with parameters marked as [Constant] is not supported",
+			messageFormat: "References to methods with parameters marked as [Constant] is currently not supported",
+			category: "Correctness",
+			defaultSeverity: DiagnosticSeverity.Error,
+			isEnabledByDefault: true
+		);
 	}
 }

tests/D2L.CodeStyle.Analyzers.Test/Specs/ConstantAttributeAnalyzer.cs

@@ -280,5 +280,17 @@ string untrusted
 
 		#endregion
 
+		#region Method Reference Tests
+
+		void MethodReferenceTests() {
+
+			{ Action<int> action = Types.SomeMethodWithParameter<int>; }
+			{ Action<int> action = /* ReferenceToMethodWithConstantParameterNotSupport */ Types.SomeMethodWithConstantParameter<int> /**/; }
+			{ Action<int, int> action = /* ReferenceToMethodWithConstantParameterNotSupport */ Types.SomeMethodWithOneConstantParameter<int> /**/; }
+			{ Action<int, int> action = /* ReferenceToMethodWithConstantParameterNotSupport */ Types.SomeMethodWithOneOtherConstantParameter<int> /**/; }
+			{ Action<int, int> action = /* ReferenceToMethodWithConstantParameterNotSupport */ Types.SomeMethodWithTwoConstantParameters<int> /**/; }
+		}
+
+		#endregion
 	}
 }