Generator: Customization for const char[]

Allow the user to choose whether `const char[]` should be marshalled as
`string` or a normal `char` array in C#.

A new option `MarshalConstCharArrayAsString` is added, and is `true`
by default.

This helps in situations where the original C++ API distinguishes
between C-strings and char arrays using the two different notations.

src/Generator/Generators/CLI/CLIMarshal.cs

@@ -61,7 +61,8 @@ namespace CppSharp.Generators.CLI
                     break;
                 case ArrayType.ArraySize.Incomplete:
                     // const char* and const char[] are the same so we can use a string
-                    if (array.Type.Desugar().IsPrimitiveType(PrimitiveType.Char) &&
+                    if (Context.Context.Options.MarshalConstCharArrayAsString &&
+                        array.Type.Desugar().IsPrimitiveType(PrimitiveType.Char) &&
                         array.QualifiedType.Qualifiers.IsConst)
                     {
                         var pointer = new PointerType { QualifiedPointee = array.QualifiedType };

src/Generator/Generators/CLI/CLITypePrinter.cs

@@ -35,7 +35,8 @@ namespace CppSharp.Generators.CLI
             TypeQualifiers quals)
         {
             // const char* and const char[] are the same so we can use a string
-            if (array.SizeType == ArrayType.ArraySize.Incomplete &&
+            if (Context.Options.MarshalConstCharArrayAsString &&
+                array.SizeType == ArrayType.ArraySize.Incomplete &&
                 array.Type.Desugar().IsPrimitiveType(PrimitiveType.Char) &&
                 array.QualifiedType.Qualifiers.IsConst)
                 return VisitCILType(new CILType(typeof(string)), quals);

src/Generator/Generators/CSharp/CSharpMarshal.cs

@@ -116,7 +116,8 @@ namespace CppSharp.Generators.CSharp
                     break;
                 case ArrayType.ArraySize.Incomplete:
                     // const char* and const char[] are the same so we can use a string
-                    if (array.Type.Desugar().IsPrimitiveType(PrimitiveType.Char) &&
+                    if (Context.Context.Options.MarshalConstCharArrayAsString &&
+                        array.Type.Desugar().IsPrimitiveType(PrimitiveType.Char) &&
                         array.QualifiedType.Qualifiers.IsConst)
                     {
                         var pointer = new PointerType { QualifiedPointee = array.QualifiedType };

src/Generator/Generators/CSharp/CSharpSources.cs

@@ -972,7 +972,7 @@ internal static bool {Helpers.TryGetNativeToManagedMappingIdentifier}(IntPtr nat
             string ptr = Generator.GeneratedIdentifier("ptr");
             if (arrayType != null)
             {
-                if (arrayType.Type.IsPrimitiveType(PrimitiveType.Char) && arrayType.SizeType != ArrayType.ArraySize.Constant)
+                if (Context.Options.MarshalConstCharArrayAsString && arrayType.Type.IsPrimitiveType(PrimitiveType.Char) && arrayType.SizeType != ArrayType.ArraySize.Constant)
                     WriteLine($"var {ptr} = {location};");
                 else
                     WriteLine($"var {ptr} = ({arrayType.Type.Visit(TypePrinter)}*){location};");

src/Generator/Generators/CSharp/CSharpTypePrinter.cs

@@ -111,7 +111,8 @@ namespace CppSharp.Generators.CSharp
             }
 
             // const char* and const char[] are the same so we can use a string
-            if (array.SizeType == ArrayType.ArraySize.Incomplete &&
+            if (Context.Options.MarshalConstCharArrayAsString &&
+                array.SizeType == ArrayType.ArraySize.Incomplete &&
                 arrayType.IsPrimitiveType(PrimitiveType.Char) &&
                 array.QualifiedType.Qualifiers.IsConst)
                 return "string";

src/Generator/Options.cs

@@ -115,7 +115,7 @@ namespace CppSharp
 
         /// <summary>
         /// Enable this option to enable generation of finalizers. Works in both CLI and
-        /// C# backends. 
+        /// C# backends.
         /// </summary>
         /// <remarks>
         /// Use <see cref="GenerateFinalizersFilter"/> to specify a filter so that
@@ -125,7 +125,7 @@ namespace CppSharp
 
         /// <summary>
         /// A filter that can restrict the classes for which finalizers are generated when
-        /// <see cref="GenerateFinalizers"/> is <c>true</c>. 
+        /// <see cref="GenerateFinalizers"/> is <c>true</c>.
         /// </summary>
         /// <remarks>
         /// The default filter performs no filtering so that whenever <see
@@ -189,6 +189,7 @@ namespace CppSharp
 
         public readonly List<string> DependentNameSpaces = new List<string>();
         public bool MarshalCharAsManagedChar { get; set; }
+        public bool MarshalConstCharArrayAsString { get; set; } = true;
 
         /// <summary>
         /// Use Span Struct instead of Managed Array