Fix for xunit/xunit#2873

src/xunit.analyzers.tests/Analyzers/X1000/MemberDataShouldReferenceValidMemberTests.cs

@@ -1137,6 +1137,38 @@ public void PuzzleOne(int _1, params string[] _2) { }
 			await Verify.VerifyAnalyzer(source);
 		}
 
+		[Fact]
+		public async void DoesNotFindWarning_WhenPassingTupleWithoutFieldNames()
+		{
+			var source = @"
+using Xunit;
+
+public class TestClass {
+	public static TheoryData<(int, int)> TestData = new TheoryData<(int, int)>();
+
+    [MemberData(nameof(TestData))]
+    public void TestMethod((int a, int b) x) { }
+}";
+
+			await Verify.VerifyAnalyzer(LanguageVersion.CSharp8, source);
+		}
+
+		[Fact]
+		public async void DoesNotFindWarning_WhenPassingTupleWithDifferentFieldNames()
+		{
+			var source = @"
+using Xunit;
+
+public class TestClass {
+	public static TheoryData<(int c, int d)> TestData = new TheoryData<(int, int)>();
+
+    [MemberData(nameof(TestData))]
+    public void TestMethod((int a, int b) x) { }
+}";
+
+			await Verify.VerifyAnalyzer(LanguageVersion.CSharp8, source);
+		}
+
 		[Fact]
 		public async void FindWarning_WithExtraValueNotCompatibleWithParamsArray()
 		{

src/xunit.analyzers/Utility/SymbolExtensions.cs

@@ -86,6 +86,14 @@ public static bool IsAssignableFrom(
 						return IsAssignableFrom(targetEnumerableType, sourceEnumerableType);
 				}
 
+				// Special handling for tuples as tuples with differently named fields are still assignable
+				if (targetType.IsTupleType && sourceType.IsTupleType)
+				{
+					ITypeSymbol targetTupleType = ((INamedTypeSymbol)targetType).TupleUnderlyingType ?? targetType;
+					ITypeSymbol sourceTupleType = ((INamedTypeSymbol)sourceType).TupleUnderlyingType ?? sourceType;
+					return SymbolEqualityComparer.Default.Equals(sourceTupleType, targetTupleType);
+				}
+
 				if (targetType.TypeKind == TypeKind.Interface)
 					return sourceType.AllInterfaces.Any(i => IsAssignableFrom(targetType, i));