Add issue provider for explicit conversions in foreach loops.

ICSharpCode.NRefactory.CSharp/ICSharpCode.NRefactory.CSharp.csproj

@@ -240,6 +240,7 @@
     <Compile Include="Parser\mcs\typespec.cs" />
     <Compile Include="Parser\mcs\visit.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="Refactoring\CodeIssues\ExplicitConversionInForEachIssue.cs" />
     <Compile Include="Refactoring\DocumentScript.cs" />
     <Compile Include="Refactoring\PatternHelper.cs" />
     <Compile Include="Refactoring\RefactoringAstHelper.cs" />

ICSharpCode.NRefactory.CSharp/Refactoring/CodeIssues/ExplicitConversionInForEachIssue.cs

@@ -0,0 +1,73 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.Collections.Generic;
+using ICSharpCode.NRefactory.CSharp.Resolver;
+using ICSharpCode.NRefactory.Semantics;
+using ICSharpCode.NRefactory.TypeSystem;
+
+namespace ICSharpCode.NRefactory.CSharp.Refactoring
+{
+	[IssueDescription("Incorrect element type in foreach over generic collection",
+	                  Description= "Detects hidden explicit conversions in foreach loops.",
+	                  Category = IssueCategories.CodeQualityIssues,
+	                  Severity = Severity.Warning)]
+	public class ExplicitConversionInForEachIssue : ICodeIssueProvider
+	{
+		public IEnumerable<CodeIssue> GetIssues (BaseRefactoringContext context)
+		{
+			var visitor = new GatherVisitor (context);
+			context.RootNode.AcceptVisitor (visitor);
+			return visitor.FoundIssues;
+		}
+
+		class GatherVisitor : GatherVisitorBase
+		{
+			CSharpConversions conversions;
+			
+			public GatherVisitor (BaseRefactoringContext ctx) : base (ctx)
+			{
+			}
+			
+			public override void VisitForeachStatement(ForeachStatement foreachStatement)
+			{
+				base.VisitForeachStatement(foreachStatement);
+				var rr = ctx.Resolve(foreachStatement) as ForEachResolveResult;
+				if (rr == null)
+					return;
+				if (rr.ElementType.Kind == TypeKind.Unknown)
+					return;
+				if (ReflectionHelper.GetTypeCode(rr.ElementType) == TypeCode.Object)
+					return;
+				if (conversions == null) {
+					conversions = CSharpConversions.Get(ctx.Compilation);
+				}
+				Conversion c = conversions.ImplicitConversion(rr.ElementType, rr.ElementVariable.Type);
+				if (c.IsValid)
+					return;
+				var csResolver = ctx.GetResolverStateBefore(foreachStatement);
+				var builder = new TypeSystemAstBuilder(csResolver);
+				AstType elementType = builder.ConvertType(rr.ElementType);
+				AstType variableType = foreachStatement.VariableType;
+				string text = ctx.TranslateString("Collection element type '{0}' is not implicitly convertible to '{1}'");
+				AddIssue(variableType, string.Format(text, elementType.GetText(), variableType.GetText()));
+			}
+		}
+	}
+}

ICSharpCode.NRefactory.Tests/CSharp/CodeIssues/ExplicitConversionInForEachIssueTests.cs

@@ -0,0 +1,75 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using ICSharpCode.NRefactory.CSharp.CodeActions;
+using ICSharpCode.NRefactory.CSharp.Refactoring;
+using NUnit.Framework;
+
+namespace ICSharpCode.NRefactory.CSharp.CodeIssues
+{
+	[TestFixture]
+	public class ExplicitConversionInForEachIssueTests : InspectionActionTestBase
+	{
+		[Test]
+		public void NoWarningOnNonGenericCollection ()
+		{
+			var input = @"class Foo {
+	void Bar (System.Collections.ArrayList c)
+	{
+		foreach (string element in c) { }
+	}
+}";
+
+			TestRefactoringContext context;
+			var issues = GetIssues (new ExplicitConversionInForEachIssue (), input, out context);
+			Assert.AreEqual (0, issues.Count);
+		}
+		
+		[Test]
+		public void NoWarningOnImplicitConversion ()
+		{
+			var input = @"class Foo {
+	void Bar (System.Collections.Generic.List<int> c)
+	{
+		foreach (double element in c) { }
+	}
+}";
+
+			TestRefactoringContext context;
+			var issues = GetIssues (new ExplicitConversionInForEachIssue (), input, out context);
+			Assert.AreEqual (0, issues.Count);
+		}
+		
+		[Test]
+		public void WarningOnExplicitConversionBetweenInterfaces ()
+		{
+			var input = @"using System.Collections.Generic;
+class Foo {
+	void Bar (IList<IList<IDisposable>> c)
+	{
+		foreach (IDisposable element in c) { }
+	}
+}";
+
+			TestRefactoringContext context;
+			var issues = GetIssues (new ExplicitConversionInForEachIssue (), input, out context);
+			Assert.AreEqual (1, issues.Count);
+		}
+	}
+}

ICSharpCode.NRefactory.Tests/ICSharpCode.NRefactory.Tests.csproj

@@ -81,6 +81,7 @@
     </Compile>
     <Compile Include="CSharp\Analysis\DefiniteAssignmentTests.cs" />
     <Compile Include="CSharp\AstStructureTests.cs" />
+    <Compile Include="CSharp\CodeIssues\ExplicitConversionInForEachIssueTests.cs" />
     <Compile Include="CSharp\CSharpAmbienceTests.cs" />
     <Compile Include="CSharp\CodeDomConvertVisitorTests.cs" />
     <Compile Include="CSharp\InsertParenthesesVisitorTests.cs" />