Analyze unsupported ArraySegment usage (#1916)

Co-authored-by: Shargon <shargon@gmail.com>

Author: Jim8y

src/Neo.SmartContract.Analyzer/CollectionTypesUsageAnalyzer.cs

@@ -60,7 +60,8 @@ public class CollectionTypesUsageAnalyzer : DiagnosticAnalyzer
             "System.Collections.BitArray",
             "System.Collections.ObjectModel.Collection<T>",
             "System.Collections.ObjectModel.ReadOnlyCollection<T>",
-            "System.Collections.ObjectModel.ReadOnlyObservableCollection<T>"
+            "System.Collections.ObjectModel.ReadOnlyObservableCollection<T>",
+            "System.ArraySegment<T>"
         };
 
         private static readonly DiagnosticDescriptor Rule = new(
@@ -192,6 +193,9 @@ private void ReportIfUnsupportedCollectionType(SyntaxNodeAnalysisContext context
 
         private static string GetSuggestedType(string originalType)
         {
+            if (originalType == "System.ArraySegment<T>")
+                return "an array or Span<T>";
+
             return originalType.Contains("Dictionary") ? "Map<TKey, TValue>" : "List<T>";
         }
     }

tests/Neo.SmartContract.Analyzer.UnitTests/CollectionTypesUsageAnalyzerUnitTests.cs

@@ -179,6 +179,49 @@ class TestClass
             await VerifyCS.VerifyAnalyzerAsync(test);
         }
 
+        [TestMethod]
+        public async Task ArraySegmentUsage_ShouldReportDiagnostic()
+        {
+            var test = TestNamespace + """
+
+                                       class TestClass
+                                       {
+                                           public void Run(byte[] buffer)
+                                           {
+                                               System.ArraySegment<byte> segment = new(buffer, 1, 2);
+                                           }
+                                       }
+                                       """;
+
+            var expected = VerifyCS.Diagnostic(CollectionTypesUsageAnalyzer.DiagnosticId)
+                .WithLocation(18, 9)
+                .WithArguments("System.ArraySegment<T>", "an array or Span<T>");
+
+            await VerifyCS.VerifyAnalyzerAsync(test, expected);
+        }
+
+        [TestMethod]
+        public async Task NestedArraySegmentSignature_ShouldReportDiagnostics()
+        {
+            var test = TestNamespace + """
+
+                                       class TestClass
+                                       {
+                                           public {|#0:System.Tuple<int, System.ArraySegment<byte>>|} Read(
+                                               {|#1:System.ArraySegment<byte>[]|} segments) => null;
+                                       }
+                                       """;
+
+            var returnDiagnostic = VerifyCS.Diagnostic(CollectionTypesUsageAnalyzer.DiagnosticId)
+                .WithLocation(0)
+                .WithArguments("System.ArraySegment<T>", "an array or Span<T>");
+            var parameterDiagnostic = VerifyCS.Diagnostic(CollectionTypesUsageAnalyzer.DiagnosticId)
+                .WithLocation(1)
+                .WithArguments("System.ArraySegment<T>", "an array or Span<T>");
+
+            await VerifyCS.VerifyAnalyzerAsync(test, returnDiagnostic, parameterDiagnostic);
+        }
+
         [TestMethod]
         public void CollectionDiagnostic_ShouldNotOfferAutomaticCodeFixes()
         {