Make DeclaredOnly and FlattenHierarchy redundant when calling GetConstructor. Fix #93.

Author: JohanLarsson

ReflectionAnalyzers.Tests/REFL006RedundantBindingFlagsTests/CodeFix.cs

@@ -10,7 +10,7 @@ internal class CodeFix
     {
         private static readonly DiagnosticAnalyzer Analyzer = new GetXAnalyzer();
         private static readonly CodeFixProvider Fix = new BindingFlagsFix();
-        private static readonly ExpectedDiagnostic ExpectedDiagnostic = ExpectedDiagnostic.Create("REFL006");
+        private static readonly ExpectedDiagnostic ExpectedDiagnostic = ExpectedDiagnostic.Create(REFL006RedundantBindingFlags.Descriptor);
 
         [TestCase("Static",           "BindingFlags.Public | BindingFlags.Static | BindingFlags.DeclaredOnly | BindingFlags.Instance",               "BindingFlags.Public | BindingFlags.Static | BindingFlags.DeclaredOnly")]
         [TestCase("Static",           "BindingFlags.Public | BindingFlags.Static | BindingFlags.DeclaredOnly | BindingFlags.NonPublic",              "BindingFlags.Public | BindingFlags.Static | BindingFlags.DeclaredOnly")]
@@ -173,5 +173,41 @@ private class Private
             var message = $"The binding flags can be more precise. Expected: {expected}.";
             AnalyzerAssert.CodeFix(Analyzer, Fix, ExpectedDiagnostic.WithMessage(message), code, fixedCode);
         }
+
+        [TestCase("GetConstructor(↓BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly, null, Type.EmptyTypes, null)")]
+        [TestCase("GetConstructor(↓BindingFlags.Public | BindingFlags.Instance | BindingFlags.FlattenHierarchy, null, Type.EmptyTypes, null)")]
+        public void GetConstructor(string call)
+        {
+            var code = @"
+namespace RoslynSandbox
+{
+    using System;
+    using System.Reflection;
+
+    class Foo
+    {
+        public Foo()
+        {
+            var member = typeof(Foo).GetConstructor(↓BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly, null, Type.EmptyTypes, null);
+        }
+    }
+}".AssertReplace("GetConstructor(↓BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly, null, Type.EmptyTypes, null)", call);
+            var fixedCode = @"
+namespace RoslynSandbox
+{
+    using System;
+    using System.Reflection;
+
+    class Foo
+    {
+        public Foo()
+        {
+            var member = typeof(Foo).GetConstructor(BindingFlags.Public | BindingFlags.Instance, null, Type.EmptyTypes, null);
+        }
+    }
+}";
+            var message = "The binding flags can be more precise. Expected: BindingFlags.Public | BindingFlags.Instance.";
+            AnalyzerAssert.CodeFix(Analyzer, Fix, ExpectedDiagnostic.WithMessage(message), code, fixedCode);
+        }
     }
 }

ReflectionAnalyzers/NodeAnalzers/GetXAnalyzer.cs

@@ -291,13 +291,17 @@ private static bool TryGetExpectedFlags(ISymbol target, ITypeSymbol targetType,
                     flags |= BindingFlags.Instance;
                 }
 
-                if (Equals(target.ContainingType, targetType))
+                if (!(target is IMethodSymbol method &&
+                      method.MethodKind == MethodKind.Constructor))
                 {
-                    flags |= BindingFlags.DeclaredOnly;
-                }
-                else if (target.IsStatic)
-                {
-                    flags |= BindingFlags.FlattenHierarchy;
+                    if (Equals(target.ContainingType, targetType))
+                    {
+                        flags |= BindingFlags.DeclaredOnly;
+                    }
+                    else if (target.IsStatic)
+                    {
+                        flags |= BindingFlags.FlattenHierarchy;
+                    }
                 }
             }
 
@@ -306,6 +310,14 @@ private static bool TryGetExpectedFlags(ISymbol target, ITypeSymbol targetType,
 
         private static bool HasRedundantFlag(ISymbol target, ITypeSymbol targetType, BindingFlags flags)
         {
+            if (target is IMethodSymbol method &&
+                method.MethodKind == MethodKind.Constructor &&
+                (flags.HasFlagFast(BindingFlags.DeclaredOnly) ||
+                 flags.HasFlagFast(BindingFlags.FlattenHierarchy)))
+            {
+                return true;
+            }
+
             if (target is ITypeSymbol &&
                 (flags.HasFlagFast(BindingFlags.Instance) ||
                  flags.HasFlagFast(BindingFlags.Static) ||

ValidCode/GetConstructor.cs

@@ -7,10 +7,10 @@ public class GetConstructor
     {
         public GetConstructor()
         {
-            _ = typeof(Default).GetConstructor(BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly, null, Type.EmptyTypes, null);
-            _ = typeof(Single).GetConstructor(BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly, null, Type.EmptyTypes, null);
-            _ = typeof(Two).GetConstructor(BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly, null, new[] { typeof(int) }, null);
-            _ = typeof(Two).GetConstructor(BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly, null, new[] { typeof(double) }, null);
+            _ = typeof(Default).GetConstructor(BindingFlags.Public | BindingFlags.Instance, null, Type.EmptyTypes, null);
+            _ = typeof(Single).GetConstructor(BindingFlags.Public | BindingFlags.Instance, null, Type.EmptyTypes, null);
+            _ = typeof(Two).GetConstructor(BindingFlags.Public | BindingFlags.Instance, null, new[] { typeof(int) }, null);
+            _ = typeof(Two).GetConstructor(BindingFlags.Public | BindingFlags.Instance, null, new[] { typeof(double) }, null);
         }
         public class Default
         {