Check 'ObjCCategoryDecl->getTypeParamList()' for null before trying to use the result.

Author: rolfbjarne

sources/libClangSharp/ClangSharp.cpp

@@ -3069,7 +3069,10 @@ int clangsharp_Cursor_getNumArguments(CXCursor C) {
         }
 
         if (const ObjCCategoryDecl* OCCD = dyn_cast<ObjCCategoryDecl>(D)) {
-            return OCCD->getTypeParamList()->size();
+            ObjCTypeParamList* typeParamList = OCCD->getTypeParamList();
+            if (typeParamList)
+                return typeParamList->size();
+            return 0;
         }
     }
 

tests/ClangSharp.UnitTests/ObjectiveCTest.cs

@@ -0,0 +1,29 @@
+// Copyright (c) .NET Foundation and Contributors. All Rights Reserved. Licensed under the MIT License (MIT). See License.md in the repository root for more information.
+
+using System.Linq;
+using NUnit.Framework;
+
+namespace ClangSharp.UnitTests;
+
+[Platform("macosx")]
+public sealed class ObjectiveCTest : TranslationUnitTest
+{
+    [Test]
+    public void Category_TypeParamList()
+    {
+        var inputContents = $@"
+@interface MyClass
+@end
+@interface MyClass (MyCategory)
+@end
+";
+
+        using var translationUnit = CreateTranslationUnit(inputContents, "objective-c++");
+
+        var categories = translationUnit.TranslationUnitDecl.Decls.OfType<ObjCCategoryDecl>().ToList ();
+        Assert.That (categories.Count, Is.EqualTo (1), "Count");
+        foreach (var c in categories) {
+            Assert.That(c.TypeParamList.Count, Is.EqualTo (0), "TypeParamList.Count");
+        }
+    }
+}

tests/ClangSharp.UnitTests/TranslationUnitTest.cs

@@ -1,5 +1,7 @@
 // Copyright (c) .NET Foundation and Contributors. All Rights Reserved. Licensed under the MIT License (MIT). See License.md in the repository root for more information.
 
+using System;
+using System.Collections.Generic;
 using System.Text;
 using ClangSharp.Interop;
 using NUnit.Framework;
@@ -19,19 +21,24 @@ public abstract class TranslationUnitTest
     protected static readonly string[] DefaultClangCommandLineArgs =
     [
         "-std=c++17",                           // The input files should be compiled for C++ 17
-        "-xc++",                                // The input files are C++
         "-Wno-pragma-once-outside-header"       // We are processing files which may be header files
     ];
 
-    protected static TranslationUnit CreateTranslationUnit(string inputContents)
+    protected static TranslationUnit CreateTranslationUnit(string inputContents, string language = "c++" /* input files are C++ by default */)
     {
         Assert.That(DefaultInputFileName, Does.Exist);
 
         using var unsavedFile = CXUnsavedFile.Create(DefaultInputFileName, inputContents);
         var unsavedFiles = new CXUnsavedFile[] { unsavedFile };
 
         var index = CXIndex.Create();
-        var translationUnit = CXTranslationUnit.Parse(index, DefaultInputFileName, DefaultClangCommandLineArgs, unsavedFiles, DefaultTranslationUnitFlags);
+        var arguments = new List<string>(DefaultClangCommandLineArgs)
+        {
+            "-x",
+            language,
+        };
+        var errorCode = CXTranslationUnit.TryParse(index, DefaultInputFileName, arguments.ToArray(), unsavedFiles, DefaultTranslationUnitFlags, out var translationUnit);
+        Assert.That(errorCode, Is.EqualTo(CXErrorCode.CXError_Success), $"Failed to create {nameof(CXTranslationUnit)} (error code: {errorCode})");
 
         if (translationUnit.NumDiagnostics != 0)
         {