Initial multi-framework experiment

src/LibYear.Core/FileTypes/XmlProjectFile.cs

@@ -12,6 +12,24 @@ public abstract class XmlProjectFile : IProjectFile
 	private readonly string[] _packageAttributeNames;
 	private readonly string _versionAttributeName;
 
+	class PackageComparer : EqualityComparer<XElement>
+	{
+		public override bool Equals(XElement? x1, XElement? x2)
+		{
+			if (x1 == null && x2 == null)
+				return true;
+			else if (x1 == null || x2 == null)
+				return false;
+
+			return (x1.Attribute("Include")?.Value == x2.Attribute("Include")?.Value);
+		}
+
+		public override int GetHashCode(XElement x)
+		{
+			return x.Attribute("Include").Value.GetHashCode();
+		}
+	}
+
 	protected XmlProjectFile(string filename, string contents, string elementName, string[] packageAttributeNames, string versionAttributeName)
 	{
 		FileName = filename;
@@ -21,7 +39,8 @@ protected XmlProjectFile(string filename, string contents, string elementName, s
 		_versionAttributeName = versionAttributeName;
 
 		_xmlContents = XDocument.Parse(contents);
-		Packages = _xmlContents.Descendants(elementName)
+		PackageComparer comparer = new PackageComparer();
+		Packages = _xmlContents.Descendants(elementName).Distinct(comparer)
 			.ToDictionary(
 				d => packageAttributeNames.Select(p => d.Attribute(p)?.Value ?? d.Element(p)?.Value).FirstOrDefault(v => v != null)!,
 				d => ParseCurrentVersion(d, versionAttributeName)