[RGen] Use the new PlatformSupportVersion in the builder.

src/rgen/Microsoft.Macios.Generator/Availability/PlatformAvailability.cs

@@ -116,11 +116,11 @@ public PlatformAvailability MergeWithParent (PlatformAvailability? parent)
 		// 1. If the parent has unsupported versions we will add them to the merge. If the kid has them, we will
 		// add them too
 		foreach (var (version, message) in parent.Value.unsupported) {
-			builder.AddUnsupportedVersion (version, message);
+			builder.AddUnsupportedVersion (new (version, SupportKind.Explicit), message);
 		}
 
 		foreach (var (version, message) in unsupported) {
-			builder.AddUnsupportedVersion (version, message);
+			builder.AddUnsupportedVersion (new (version, SupportKind.Explicit), message);
 		}
 
 		// 2. if supported in the platform, we will always pick the larges version between
@@ -130,7 +130,7 @@ public PlatformAvailability MergeWithParent (PlatformAvailability? parent)
 			? parent.Value.SupportedVersion
 			: SupportedVersion;
 		if (supportedVersion is not null)
-			builder.AddSupportedVersion (supportedVersion);
+			builder.AddSupportedVersion (new (supportedVersion, SupportKind.Explicit));
 
 		// similar to the unsupported versions, if the parent has obsolete ones, we will add them
 		foreach (var (version, obsoleteInfo) in parent.Value.obsoleted) {

src/rgen/Microsoft.Macios.Generator/Availability/PlatformAvailabilityBuilder.cs

@@ -19,9 +19,10 @@ readonly partial struct PlatformAvailability {
 	/// A writable PlatformAvailability accessor.
 	/// </summary>
 	public sealed class Builder {
+		static readonly PlatformSupportVersionComparer versionComparer = new ();
 		readonly ApplePlatform platform;
-		Version? supportedVersion;
-		readonly SortedDictionary<Version, string?> unsupported = new ();
+		PlatformSupportVersion? supportedVersion;
+		readonly SortedDictionary<PlatformSupportVersion, string?> unsupported = new (versionComparer);
 		readonly SortedDictionary<Version, (string? Message, string? Url)> obsoleted = new ();
 
 		/// <summary>
@@ -36,15 +37,16 @@ public sealed class Builder {
 		/// else the version is ignored.
 		/// </summary>
 		/// <param name="version">A new supported version.</param>
-		internal void AddSupportedVersion (Version version)
+		internal void AddSupportedVersion (PlatformSupportVersion version)
 		{
-			if (unsupported.ContainsKey (defaultVersion))
-				// platform is unsupported, do nothing
+			if (unsupported.ContainsKey (PlatformSupportVersion.ExplicitDefault))
+				// platform is explicitly unsupported, do nothing
 				return;
 
 			// update the supported version to the larges of the two
-			if (supportedVersion is null || version > supportedVersion)
-				supportedVersion = version;
+			supportedVersion = supportedVersion is null
+				? version
+				: PlatformSupportVersion.Max (version, supportedVersion.Value);
 		}
 
 		/// <summary>
@@ -57,32 +59,35 @@ public void Add (SupportedOSPlatformData supportedPlatform)
 			if (supportedPlatform.Platform != platform)
 				return;
 			// no version is present, therefore try to set the default one
-			AddSupportedVersion (supportedPlatform.Version);
+			AddSupportedVersion (new (supportedPlatform.Version, SupportKind.Explicit));
 		}
 
 		/// <summary>
 		/// Adds a new version to the list of unsupported versions. If the platform is unsupported, the version is ignored.
 		/// </summary>
 		/// <param name="version">The new unsupported version.</param>
 		/// <param name="message">The optional message of the unsupported version.</param>
-		internal void AddUnsupportedVersion (Version version, string? message)
+		internal void AddUnsupportedVersion (PlatformSupportVersion version, string? message)
 		{
 			// adding an unsupported version, due to the way the API is designed is more complicated. It can be
 			// that a selector/member is unsupported in more than one version, so we need to keep track of that
 			// the only time in which we make an exception is when we unsupported a platform (no version number)
 			// if that is the case, we will remove all unsupported versions and just un-support the platform
 			// ignore data from platforms that we do not care
-			if (version == defaultVersion) {
+			if (version == PlatformSupportVersion.ExplicitDefault) {
 				unsupported.Clear ();
-				unsupported [defaultVersion] = message;
+				unsupported [PlatformSupportVersion.ExplicitDefault] = message;
 				// we are unsupporting the platform! that means if we supported it or any version, that should be
 				// set back to null
 				supportedVersion = null;
 			} else {
 				// we have a version, that does not mean we do care about that data, first we want to check
 				// that we did not fully unsupported the platform, if that is the case, we ignore this version
-				if (unsupported.ContainsKey (defaultVersion))
+				if (unsupported.ContainsKey (PlatformSupportVersion.ExplicitDefault))
 					return;
+
+				// we implicitly unsupported the platform, remove that entry since we are adding a version
+				unsupported.Remove (PlatformSupportVersion.ImplicitDefault);
 				unsupported [version] = message;
 			}
 		}
@@ -95,7 +100,7 @@ public void Add (UnsupportedOSPlatformData unsupportedPlatform)
 		{
 			if (unsupportedPlatform.Platform != platform)
 				return;
-			AddUnsupportedVersion (unsupportedPlatform.Version, unsupportedPlatform.Message);
+			AddUnsupportedVersion (new (unsupportedPlatform.Version, SupportKind.Explicit), unsupportedPlatform.Message);
 		}
 
 
@@ -137,7 +142,11 @@ public void Add (ObsoletedOSPlatformData obsoletedPlatform)
 		/// <returns>A new readonly structure that contains the platform availability.</returns>
 		public PlatformAvailability ToImmutable ()
 		{
-			return new PlatformAvailability (platform, supportedVersion, unsupported, obsoleted);
+			var unsupportedCopy = new SortedDictionary<Version, string?> ();
+			foreach (var (version, message) in unsupported) {
+				unsupportedCopy.Add (version.Version, message);
+			}
+			return new PlatformAvailability (platform, supportedVersion?.Version, unsupportedCopy, obsoleted);
 		}
 
 		/// <summary>

src/rgen/Microsoft.Macios.Generator/Availability/PlatformSupportVersion.cs

@@ -34,6 +34,23 @@ public readonly record struct PlatformSupportVersion {
 		Kind = SupportKind.Explicit
 	};
 
+	/// <summary>
+	/// Initializes a new instance of the <see cref="PlatformSupportVersion"/> struct.
+	/// </summary>
+	/// <param name="version">The version number.</param>
+	/// <param name="kind">The kind of support.</param>
+	public PlatformSupportVersion (Version version, SupportKind kind)
+	{
+		Version = version;
+		Kind = kind;
+	}
+
+	/// <summary>
+	/// Initializes a new instance of the <see cref="PlatformSupportVersion"/> struct with an explicit support kind.
+	/// </summary>
+	/// <param name="version">The version number.</param>
+	public PlatformSupportVersion (Version version) : this (version, SupportKind.Explicit) { }
+
 	/// <summary>
 	/// Returns the platform support version with the highest precedence.
 	/// </summary>

src/rgen/Microsoft.Macios.Generator/Availability/PlatformSupportVersionComparer.cs

@@ -0,0 +1,25 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.Collections.Generic;
+
+namespace Microsoft.Macios.Generator.Availability;
+
+/// <summary>
+/// Compares two <see cref="PlatformSupportVersion"/> instances for sorting.
+/// </summary>
+public class PlatformSupportVersionComparer : IComparer<PlatformSupportVersion> {
+
+	/// <summary>
+	/// Compares two platform support versions and returns a value indicating whether one is less than, equal to, or greater than the other.
+	/// </summary>
+	/// <param name="x">The first object to compare.</param>
+	/// <param name="y">The second object to compare.</param>
+	/// <returns>A signed integer that indicates the relative values of x and y.</returns>
+	public int Compare (PlatformSupportVersion x, PlatformSupportVersion y)
+	{
+		int versionComparison = x.Version.CompareTo (y.Version);
+		if (versionComparison != 0) return versionComparison;
+		return x.Kind.CompareTo (y.Kind);
+	}
+}

src/rgen/Microsoft.Macios.Generator/Availability/SymbolAvailabilityBuilder.cs

@@ -90,7 +90,7 @@ internal void AddSupportedVersion (ApplePlatform platform, Version version)
 			if (!supportedPlatforms.Contains (platform))
 				return;
 			var builder = GetBuilder (platform);
-			builder.AddSupportedVersion (version);
+			builder.AddSupportedVersion (new (version, SupportKind.Explicit));
 		}
 
 		/// <summary>
@@ -118,7 +118,7 @@ internal void AddUnsupportedVersion (ApplePlatform platform, Version version, st
 				return;
 
 			var builder = GetBuilder (platform);
-			builder.AddUnsupportedVersion (version, message);
+			builder.AddUnsupportedVersion (new (version, SupportKind.Explicit), message);
 		}
 
 		/// <summary>

tests/rgen/Microsoft.Macios.Generator.Tests/Availability/PlatformAvailabilityEqualityTests.cs

@@ -26,8 +26,8 @@ public void EqualSamePlatformDifferentSupportedVersion ()
 	{
 		var leftBuilder = PlatformAvailability.CreateBuilder (ApplePlatform.iOS);
 		var rightBuilder = PlatformAvailability.CreateBuilder (ApplePlatform.TVOS);
-		leftBuilder.AddSupportedVersion (new Version (12, 0));
-		rightBuilder.AddSupportedVersion (new Version (10, 0));
+		leftBuilder.AddSupportedVersion (new (new Version (12, 0)));
+		rightBuilder.AddSupportedVersion (new (new Version (10, 0)));
 		var left = leftBuilder.ToImmutable ();
 		var right = rightBuilder.ToImmutable ();
 		Assert.False (left.Equals (right));
@@ -41,7 +41,7 @@ public void EqualsNullSupportedVersion ()
 	{
 		var leftBuilder = PlatformAvailability.CreateBuilder (ApplePlatform.iOS);
 		var rightBuilder = PlatformAvailability.CreateBuilder (ApplePlatform.TVOS);
-		leftBuilder.AddSupportedVersion (new Version (12, 0));
+		leftBuilder.AddSupportedVersion (new (new Version (12, 0)));
 		var left = leftBuilder.ToImmutable ();
 		var right = rightBuilder.ToImmutable ();
 		Assert.False (left.Equals (right));
@@ -55,9 +55,9 @@ public void EqualSamePlatformSameSupportedVersionDifferentUnsupportedVersion ()
 	{
 		var leftBuilder = PlatformAvailability.CreateBuilder (ApplePlatform.iOS);
 		var rightBuilder = PlatformAvailability.CreateBuilder (ApplePlatform.TVOS);
-		leftBuilder.AddSupportedVersion (new Version (12, 0));
-		leftBuilder.AddUnsupportedVersion (new Version (10, 0), "Unsupported");
-		rightBuilder.AddSupportedVersion (new Version (12, 0));
+		leftBuilder.AddSupportedVersion (new (new Version (12, 0)));
+		leftBuilder.AddUnsupportedVersion (new (new Version (10, 0)), "Unsupported");
+		rightBuilder.AddSupportedVersion (new (new Version (12, 0)));
 		var left = leftBuilder.ToImmutable ();
 		var right = rightBuilder.ToImmutable ();
 		Assert.False (left.Equals (right));
@@ -71,11 +71,11 @@ public void EqualsSamePlatformSamerSupportedVersionSameUnsupportedDiffObsolete (
 	{
 		var leftBuilder = PlatformAvailability.CreateBuilder (ApplePlatform.iOS);
 		var rightBuilder = PlatformAvailability.CreateBuilder (ApplePlatform.TVOS);
-		leftBuilder.AddSupportedVersion (new Version (12, 0));
-		leftBuilder.AddUnsupportedVersion (new Version (10, 0), "Unsupported");
+		leftBuilder.AddSupportedVersion (new (new Version (12, 0)));
+		leftBuilder.AddUnsupportedVersion (new (new Version (10, 0)), "Unsupported");
 		leftBuilder.AddObsoletedVersion (new Version (12, 0), "Obsolete", null);
-		rightBuilder.AddSupportedVersion (new Version (12, 0));
-		rightBuilder.AddUnsupportedVersion (new Version (10, 0), "Unsupported");
+		rightBuilder.AddSupportedVersion (new (new Version (12, 0)));
+		rightBuilder.AddUnsupportedVersion (new (new Version (10, 0)), "Unsupported");
 		leftBuilder.AddObsoletedVersion (new Version (12, 0), "Obsolete", "url");
 		var left = leftBuilder.ToImmutable ();
 		var right = rightBuilder.ToImmutable ();