Fix NRE in TypedConstantComparer (#69062)

dotnet · Jul 17, 2023 · 4b7d601 · 4b7d601
1 parent d49a1c2
commit 4b7d601
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Showing 2 changed files with 26 additions and 7 deletions.
diff --git a/src/EditorFeatures/CSharpTest/EditAndContinue/TopLevelEditingTests.cs b/src/EditorFeatures/CSharpTest/EditAndContinue/TopLevelEditingTests.cs
@@ -1067,6 +1067,25 @@ public void Type_Attribute_Delete_NotSupportedByRuntime2()
                 capabilities: EditAndContinueCapabilities.Baseline);
         }
 
+        [Fact]
+        [WorkItem("https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1831006")]
+        public void Type_Attribute_Update_Null()
+        {
+            var attribute = @"
+using System;
+public class A : Attribute { public A1(int[] array, Type type, Type[] types) {} }
+";
+
+            var src1 = attribute + "[A(null, null, new Type[] { typeof(C) })]class C { }";
+            var src2 = attribute + "[A(null, null, null)]class C { }";
+
+            var edits = GetTopEdits(src1, src2);
+
+            edits.VerifySemantics(
+                semanticEdits: new[] { SemanticEdit(SemanticEditKind.Update, c => c.GetMember("C")) },
+                capabilities: EditAndContinueCapabilities.ChangeCustomAttributes);
+        }
+
         [Fact]
         public void Type_Attribute_Change_Reloadable()
         {

diff --git a/src/Features/Core/Portable/EditAndContinue/AbstractEditAndContinueAnalyzer.cs b/src/Features/Core/Portable/EditAndContinue/AbstractEditAndContinueAnalyzer.cs
@@ -6632,17 +6632,17 @@ internal static void AddNodes<T>(ArrayBuilder<SyntaxNode> nodes, SeparatedSyntax
 
         private sealed class TypedConstantComparer : IEqualityComparer<TypedConstant>
         {
-            public static TypedConstantComparer Instance = new TypedConstantComparer();
+            public static readonly TypedConstantComparer Instance = new();
 
             public bool Equals(TypedConstant x, TypedConstant y)
-                => x.Kind.Equals(y.Kind) &&
-                   x.IsNull.Equals(y.IsNull) &&
+                => x.Kind == y.Kind &&
+                   x.IsNull == y.IsNull &&
                    SymbolEquivalenceComparer.Instance.Equals(x.Type, y.Type) &&
                    x.Kind switch
                    {
-                       TypedConstantKind.Array => x.Values.SequenceEqual(y.Values, TypedConstantComparer.Instance),
-                       TypedConstantKind.Type => TypesEquivalent(x.Value as ITypeSymbol, y.Value as ITypeSymbol, exact: false),
-                       _ => object.Equals(x.Value, y.Value)
+                       TypedConstantKind.Array => x.Values.IsDefault || x.Values.SequenceEqual(y.Values, Instance),
+                       TypedConstantKind.Type => TypesEquivalent((ITypeSymbol?)x.Value, (ITypeSymbol?)y.Value, exact: false),
+                       _ => Equals(x.Value, y.Value)
                    };
 
             public int GetHashCode(TypedConstant obj)
@@ -6651,7 +6651,7 @@ public int GetHashCode(TypedConstant obj)
 
         private sealed class NamedArgumentComparer : IEqualityComparer<KeyValuePair<string, TypedConstant>>
         {
-            public static NamedArgumentComparer Instance = new NamedArgumentComparer();
+            public static readonly NamedArgumentComparer Instance = new();
 
             public bool Equals(KeyValuePair<string, TypedConstant> x, KeyValuePair<string, TypedConstant> y)
                 => x.Key.Equals(y.Key) &&