Fixed bug in LoadString overload (#570)

Author: dahall

CodeGen/Generator/VanaraAttributeGenerator.cs

@@ -460,7 +460,8 @@ private static void BuildAddAsMethod(SourceProductionContext context, Compilatio
 				var paramNode = tmpbuilder.docs?.SelectSingleNode($"//param[@name='{ps.Identifier.Text}']");
 				var returnsNode = tmpbuilder.docs?.SelectSingleNode("//returns") ??
 					tmpbuilder.docs?.DocumentElement?.AppendChild(tmpbuilder.docs?.CreateElement("returns")!);
-				returnsNode?.InnerXml = paramNode?.InnerXml;
+				if (returnsNode is not null)
+					returnsNode.InnerXml = paramNode?.InnerXml;
 				paramNode?.ParentNode?.RemoveChild(paramNode);
 			}
 		}

PInvoke/User32/WinUser.Res.cs

@@ -379,7 +379,7 @@ public static SafeHICON LoadImage_Icon([Optional] HINSTANCE hinst, SafeResourceI
 	/// </returns>
 	[PInvokeData("WinUser.h", MSDNShortId = "ms647486")]
 	[DllImport(Lib.User32, CharSet = CharSet.Auto, SetLastError = true)]
-	[System.Security.SecurityCritical]
+	[System.Security.SecurityCritical, SuppressAutoGen]
 	public static extern int LoadString(HINSTANCE hInstance, int uID, StringBuilder lpBuffer, int nBufferMax);
 
 	/// <summary>Loads a string resource from the executable file associated with a specified module.</summary>
@@ -390,17 +390,16 @@ public static SafeHICON LoadImage_Icon([Optional] HINSTANCE hinst, SafeResourceI
 	/// <param name="uID">The identifier of the string to be loaded.</param>
 	/// <returns>If the function succeeds, the return value is the full resource string.</returns>
 	[PInvokeData("WinUser.h", MSDNShortId = "ms647486")]
-	public static string LoadString(HINSTANCE hInstance, int uID)
+	public static string? LoadString(HINSTANCE hInstance, int uID)
 	{
-		IntPtr p = default;
-		var l = LoadString(hInstance, uID, p, 0);
+		var l = LoadString(hInstance, uID, out var p);
 		if (l == 0) Win32Error.ThrowLastError();
-		return StringHelper.GetString(p, CharSet.Auto, l * Marshal.SystemDefaultCharSize)!;
+		return p;
 	}
 
 	[DllImport(Lib.User32, CharSet = CharSet.Auto, SetLastError = true)]
 	[System.Security.SecurityCritical]
-	private static extern int LoadString(HINSTANCE hInstance, int uID, IntPtr lpBuffer, int nBufferMax);
+	private static extern int LoadString(HINSTANCE hInstance, int uID, out StrPtrAuto lpBuffer, int nBufferMax = 0);
 
 	/// <summary/>
 	[StructLayout(LayoutKind.Sequential, Pack = 1)]

UnitTests/PInvoke/User32/User32Tests.cs

@@ -185,7 +185,12 @@ public void GetSetWindowLongTest()
 	public void LoadImageTest() => throw new NotImplementedException();
 
 	[Test]
-	public void LoadStringTest() => throw new NotImplementedException();
+	public void LoadStringTest()
+	{
+		using var lib = Kernel32.LoadLibraryEx(TestCaseSources.ResourceFile, Kernel32.LoadLibraryExFlags.LOAD_LIBRARY_AS_DATAFILE);
+		Assert.That(lib, ResultIs.ValidHandle);
+		Assert.That(LoadString(lib, 103), Is.EqualTo("DummyResourceExe"));
+	}
 
 	[Test]
 	public void LoadStringTest1() => throw new NotImplementedException();