Fix generate-macro-bindings generation

sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.VisitPreprocessedEntity.cs

@@ -34,7 +34,7 @@ private unsafe void VisitMacroDefinitionRecord(MacroDefinitionRecord macroDefini
             var macroName = $"ClangSharpMacro_{macroDefinitionRecord.Spelling}";
 
             _ = _fileContentsBuilder.Append('\n');
-            _ = _fileContentsBuilder.Append($"const auto {macroName} = ");
+            _ = _fileContentsBuilder.Append($"const {_placeholderMacroType} {macroName} = ");
 
             var sourceRangeEnd = tokens[^1].GetExtent(translationUnitHandle).End;
             var sourceRangeStart = tokens[1].GetLocation(translationUnitHandle);

sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.cs

@@ -62,13 +62,13 @@ public sealed partial class PInvokeGenerator : IDisposable
     private readonly Dictionary<string, List<string>> _topLevelClassAttributes;
     private readonly HashSet<string> _topLevelClassNames;
     private readonly HashSet<string> _usedRemappings;
+    private readonly string _placeholderMacroType;
 
     private string _filePath;
     private string[] _clangCommandLineArgs;
     private CXTranslationUnit_Flags _translationFlags;
     private string? _currentClass;
     private string? _currentNamespace;
-
     private IOutputBuilder? _outputBuilder;
     private CSharpOutputBuilder? _testOutputBuilder;
     private CSharpOutputBuilder? _stmtOutputBuilder;
@@ -135,6 +135,7 @@ public PInvokeGenerator(PInvokeGeneratorConfiguration config, Func<string, Strea
         _usedRemappings = new HashSet<string>();
         _filePath = "";
         _clangCommandLineArgs = Array.Empty<string>();
+        _placeholderMacroType = GetPlaceholderMacroType();
     }
 
     ~PInvokeGenerator()
@@ -6095,7 +6096,7 @@ private void WithAttributes(NamedDecl namedDecl, bool onlySupportedOSPlatform =
                 if (IsType<TypedefType>(fieldDecl, out var typedefType))
                 {
                     declAttrs = declAttrs.Concat(typedefType.Decl.Attrs);
-                }          
+                }
             }
             else if (namedDecl is RecordDecl recordDecl)
             {
@@ -6532,4 +6533,54 @@ private void StopCSharpCode()
             }
         }
     }
-}
+
+    private string GetPlaceholderMacroType()
+    {
+        const string Cxx11AutoType = "auto";
+        const string GnuAutoType = "__auto_type";
+
+        if (_config.Language is "c++")
+        {
+            if (string.IsNullOrEmpty(_config.LanguageStandard))
+            {
+                return Cxx11AutoType; // Nowadays, the default standard within clang will always be above c++11
+            }
+
+            var cxxStandard = ParseCxxStandard(_config.LanguageStandard);
+            return (cxxStandard is not -1 and not 98 and >= 11) ? Cxx11AutoType : GnuAutoType;
+        }
+        else
+        {
+            return GnuAutoType;
+        }
+    }
+
+    private static int ParseCxxStandard(string standard)
+    {
+        const string CxxStandard = "c++";
+        const string GnuxxStandard = "gnu++";
+
+        if (standard.StartsWith(CxxStandard))
+        {
+            return ParseCxxStandardVersion(standard.AsSpan()[CxxStandard.Length..]);
+        }
+
+        if (standard.StartsWith(GnuxxStandard))
+        {
+            return ParseCxxStandardVersion(standard.AsSpan()[GnuxxStandard.Length..]);
+        }
+
+        return -1;
+    }
+
+    private static int ParseCxxStandardVersion(ReadOnlySpan<char> version)
+    {
+        // Maybe in the future we'll need to check for more c++ standard drafts, but atm this should work
+        if(version.EndsWith("a") || version.EndsWith("b"))
+        {
+            return int.TryParse(version[..^1], out var draftStd) ? draftStd * 10 : -1;
+        }
+
+        return int.TryParse(version, out var std) ? std : -1;
+    }
+}

sources/ClangSharp.PInvokeGenerator/PInvokeGeneratorConfiguration.cs

@@ -15,6 +15,9 @@ public sealed class PInvokeGeneratorConfiguration
     private const string DefaultMethodPrefixToStripValue = "";
     private const string DefaultTestOutputLocationValue = "";
 
+    private readonly string _language;
+    private readonly string _languageStandard;
+
     private readonly string _defaultNamespace;
     private readonly string _headerText;
     private readonly string _libraryPath;
@@ -49,8 +52,11 @@ public sealed class PInvokeGeneratorConfiguration
 
     private PInvokeGeneratorConfigurationOptions _options;
 
-    public PInvokeGeneratorConfiguration(string defaultNamespace, string outputLocation, string? headerFile, PInvokeGeneratorOutputMode outputMode, PInvokeGeneratorConfigurationOptions options)
+    public PInvokeGeneratorConfiguration(string language, string languageStandard, string defaultNamespace, string outputLocation, string? headerFile, PInvokeGeneratorOutputMode outputMode, PInvokeGeneratorConfigurationOptions options)
     {
+        _language = language;
+        _languageStandard = languageStandard;
+
         if (string.IsNullOrWhiteSpace(defaultNamespace))
         {
             throw new ArgumentNullException(nameof(defaultNamespace));
@@ -321,6 +327,10 @@ public IReadOnlyCollection<string> NativeTypeNamesToStrip
 
     public string OutputLocation => _outputLocation;
 
+    public string Language => _language;
+
+    public string LanguageStandard => _languageStandard;
+
     [AllowNull]
     public IReadOnlyDictionary<string, string> RemappedNames
     {

sources/ClangSharpPInvokeGenerator/Program.cs

@@ -691,7 +691,7 @@ public static void Run(InvocationContext context)
         translationFlags |= CXTranslationUnit_IncludeAttributedTypes;               // Include attributed types in CXType
         translationFlags |= CXTranslationUnit_VisitImplicitAttributes;              // Implicit attributes should be visited
 
-        var config = new PInvokeGeneratorConfiguration(namespaceName, outputLocation, headerFile, outputMode, configOptions) {
+        var config = new PInvokeGeneratorConfiguration(language, std, namespaceName, outputLocation, headerFile, outputMode, configOptions) {
             DefaultClass = methodClassName,
             ExcludedNames = excludedNames,
             IncludedNames = includedNames,
@@ -1062,7 +1062,7 @@ private static Option<string> GetLanguageOption()
             aliases: new string[] { "--language", "-x" },
             description: "Treat subsequent input files as having type <language>.",
             getDefaultValue: () => "c++"
-        );
+        ).FromAmong("c", "c++");
     }
 
     private static Option<string> GetLibraryOption()

tests/ClangSharp.PInvokeGenerator.UnitTests/CTest.cs

@@ -63,7 +63,7 @@ public partial struct MyStruct
 ";
         }
 
-        return ValidateGeneratedCSharpLatestWindowsBindingsAsync(inputContents, expectedOutputContents, commandlineArgs: DefaultCClangCommandLineArgs);
+        return ValidateGeneratedCSharpLatestWindowsBindingsAsync(inputContents, expectedOutputContents, commandlineArgs: DefaultCClangCommandLineArgs, language: "c", languageStandard: DefaultCStandard);
     }
 
     [Test]
@@ -97,7 +97,7 @@ public unsafe partial struct _MyOtherStruct
     }
 }
 ";
-        return ValidateGeneratedCSharpLatestWindowsBindingsAsync(inputContents, expectedOutputContents, commandlineArgs: DefaultCClangCommandLineArgs);
+        return ValidateGeneratedCSharpLatestWindowsBindingsAsync(inputContents, expectedOutputContents, commandlineArgs: DefaultCClangCommandLineArgs, language: "c", languageStandard: DefaultCStandard);
     }
 
     [Test]
@@ -138,6 +138,28 @@ public unsafe partial struct _MyOtherUnion
     }
 }
 ";
-        return ValidateGeneratedCSharpLatestWindowsBindingsAsync(inputContents, expectedOutputContents, commandlineArgs: DefaultCClangCommandLineArgs);
+        return ValidateGeneratedCSharpLatestWindowsBindingsAsync(inputContents, expectedOutputContents, commandlineArgs: DefaultCClangCommandLineArgs, language: "c", languageStandard: DefaultCStandard);
+    }
+
+    [Test]
+    public Task MacroTest()
+    {
+        var inputContents = @"#define MyMacro1 5
+#define MyMacro2 MyMacro1";
+
+        var expectedOutputContents = @"namespace ClangSharp.Test
+{
+    public static partial class Methods
+    {
+        [NativeTypeName(""#define MyMacro1 5"")]
+        public const int MyMacro1 = 5;
+
+        [NativeTypeName(""#define MyMacro2 MyMacro1"")]
+        public const int MyMacro2 = 5;
+    }
+}
+";
+
+        return ValidateGeneratedCSharpLatestWindowsBindingsAsync(inputContents, expectedOutputContents, commandlineArgs: DefaultCClangCommandLineArgs, language: "c", languageStandard: DefaultCStandard);
     }
 }