BUIGFIX: Infinite recursion when comparing generic parameter.

Fix #212

Author: JohanLarsson

IDisposableAnalyzers.Test/Helpers/AssignedValueWalkerTests/AssignedValueWalkerTests.cs

@@ -1,4 +1,4 @@
-namespace IDisposableAnalyzers.Test.Helpers.AssignedValueWalkerTests
+namespace IDisposableAnalyzers.Test.Helpers.AssignedValueWalkerTests
 {
     using System.Threading;
     using Gu.Roslyn.Asserts;
@@ -43,5 +43,33 @@ internal void M()
             var actual = string.Join(", ", assignedValues);
             Assert.AreEqual(expected, actual);
         }
+
+        [Test]
+        public static void GenericOut()
+        {
+            var syntaxTree = CSharpSyntaxTree.ParseText(@"
+namespace N
+{
+    public sealed class C
+    {
+        public T M<T>(out T t1)
+        {
+            return M(0, out t1);
+        }
+
+        public T M<T>(int _, out T t2)
+        {
+            t2 = default;
+            return default;
+        }
+    }
+}");
+            var compilation = CSharpCompilation.Create("test", new[] { syntaxTree }, MetadataReferences.FromAttributes());
+            var semanticModel = compilation.GetSemanticModel(syntaxTree);
+            var argument = syntaxTree.FindArgument("t1");
+            using var assignedValues = AssignedValueWalker.Borrow(argument.Expression, semanticModel, CancellationToken.None);
+            var actual = string.Join(", ", assignedValues);
+            Assert.AreEqual("default", actual);
+        }
     }
 }

IDisposableAnalyzers.Test/IDISP001DisposeCreatedTests/Valid.Recursion.cs

@@ -153,6 +153,29 @@ private static IDisposable WithOptionalParameter(IDisposable value, IEnumerable<
             return value;
         }
     }
+}";
+            RoslynAssert.Valid(Analyzer, code);
+        }
+
+        [Test]
+        public static void GenericOut()
+        {
+            var code = @"
+namespace N
+{
+    public sealed class C
+    {
+        public T M<T>(out T t)
+        {
+            return M(0, out t);
+        }
+
+        public T M<T>(int _, out T t)
+        {
+            t = default;
+            return default;
+        }
+    }
 }";
             RoslynAssert.Valid(Analyzer, code);
         }

IDisposableAnalyzers/Analyzers/ArgumentAnalyzer.cs

@@ -47,8 +47,7 @@ private static void Handle(SyntaxNodeAnalysisContext context)
 
         private static bool IsCreation(ArgumentSyntax candidate, SemanticModel semanticModel, CancellationToken cancellationToken)
         {
-            if (candidate.Parent is ArgumentListSyntax argumentList &&
-                argumentList.Parent is InvocationExpressionSyntax invocation &&
+            if (candidate.Parent is ArgumentListSyntax { Parent: InvocationExpressionSyntax invocation } &&
                 semanticModel.TryGetSymbol(invocation, cancellationToken, out var method) &&
                 method.TryFindParameter(candidate, out var parameter) &&
                 Disposable.IsPotentiallyAssignableFrom(parameter.Type, semanticModel.Compilation))

IDisposableAnalyzers/Helpers/Walkers/AssignedValueWalker.cs

@@ -4,6 +4,7 @@
     using System.Collections;
     using System.Collections.Generic;
     using System.Diagnostics.CodeAnalysis;
+    using System.Linq;
     using System.Threading;
     using Gu.Roslyn.AnalyzerExtensions;
     using Microsoft.CodeAnalysis;
@@ -15,8 +16,8 @@ internal sealed class AssignedValueWalker : PooledWalker<AssignedValueWalker>, I
         private readonly List<ExpressionSyntax> values = new List<ExpressionSyntax>();
         private readonly List<ExpressionSyntax> outValues = new List<ExpressionSyntax>();
         private readonly MemberWalkers memberWalkers = new MemberWalkers();
-        private readonly HashSet<IParameterSymbol> refParameters = new HashSet<IParameterSymbol>(SymbolComparer.Default);
-        private readonly HashSet<IParameterSymbol> outParameters = new HashSet<IParameterSymbol>(SymbolComparer.Default);
+        private readonly HashSet<IParameterSymbol> refParameters = new HashSet<IParameterSymbol>(ParameterSymbolComparer.Default);
+        private readonly HashSet<IParameterSymbol> outParameters = new HashSet<IParameterSymbol>(ParameterSymbolComparer.Default);
         private readonly PublicMemberWalker publicMemberWalker;
         private readonly CtorArgWalker ctorArgWalker;
 
@@ -711,7 +712,7 @@ bool TryGetProperty(out IPropertySymbol? result)
             }
         }
 
-        private struct Context
+        private readonly struct Context
         {
             internal readonly SyntaxNode Node;
             private readonly StatementSyntax? stopAt;

IDisposableAnalyzers/IDisposableAnalyzers.csproj

@@ -45,7 +45,7 @@
 
   <ItemGroup>
     <PackageReference Include="Gu.Analyzers" Version="1.6.7-dev" PrivateAssets="all" />
-    <PackageReference Include="Gu.Roslyn.Extensions" Version="0.12.5-dev" />
+    <PackageReference Include="Gu.Roslyn.Extensions" Version="0.12.6-dev" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="3.3.1" />
     <PackageReference Include="Microsoft.CodeAnalysis.FxCopAnalyzers" Version="2.9.8" PrivateAssets="all" />
     <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.164" PrivateAssets="all" />

ValidCode/Recursion/Issue212.cs

@@ -0,0 +1,17 @@
+namespace ValidCode.Recursion
+{
+    class Issue212
+    {
+        public void M<T>(out T str)
+        {
+            str = default;
+            //return M(0, out str);
+        }
+
+        public T M<T>(int _, out T str)
+        {
+            str = default;
+            return default;
+        }
+    }
+}