Add NU1703 warning for packages using deprecated MonoAndroid framework

src/NuGet.Core/NuGet.Commands/RestoreCommand/LockFileBuilder.cs

@@ -186,6 +186,8 @@ public LockFile CreateLockFile(LockFile previousLockFile,
                     && (target.TargetFramework is FallbackFramework
                         || target.TargetFramework is AssetTargetFallbackFramework);
 
+                bool checkMonoAndroidDeprecation = MonoAndroidDeprecation.ShouldCheck(project, targetGraph.Framework);
+
                 foreach (var graphItem in targetGraph.Flattened.OrderBy(x => x.Key))
                 {
                     var library = graphItem.Key;
@@ -280,6 +282,28 @@ public LockFile CreateLockFile(LockFile previousLockFile,
                                 librariesWithWarnings.Add(library);
                             }
                         }
+
+                        // Log NU1703 warning if the package uses the deprecated MonoAndroid framework
+                        if (checkMonoAndroidDeprecation
+                            && !librariesWithWarnings.Contains(library)
+                            && MonoAndroidDeprecation.UsesMonoAndroidFramework(targetLibrary))
+                        {
+                            var message = string.Format(CultureInfo.CurrentCulture,
+                                Strings.Warning_MonoAndroidFrameworkDeprecated,
+                                library.Name,
+                                library.Version);
+
+                            var logMessage = RestoreLogMessage.CreateWarning(
+                                NuGetLogCode.NU1703,
+                                message,
+                                library.Name,
+                                targetGraph.TargetGraphName);
+
+                            _logger.Log(logMessage);
+
+                            // only log the warning once per library
+                            librariesWithWarnings.Add(library);
+                        }
                     }
                 }
 

src/NuGet.Core/NuGet.Commands/RestoreCommand/MonoAndroidDeprecation.cs

@@ -0,0 +1,84 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using NuGet.Frameworks;
+using NuGet.ProjectModel;
+
+namespace NuGet.Commands
+{
+    /// <summary>
+    /// Detects when a package uses the deprecated MonoAndroid framework instead of net6.0-android or later.
+    /// This warning is gated on .NET 11 SDK (SdkAnalysisLevel >= 11.0.100) and targeting net11.0-android or later.
+    /// </summary>
+    internal static class MonoAndroidDeprecation
+    {
+        /// <summary>
+        /// Determines whether the MonoAndroid deprecation check should be performed for the given project and target framework.
+        /// </summary>
+        /// <param name="project">The package spec containing restore metadata.</param>
+        /// <param name="framework">The target framework of the current graph.</param>
+        /// <returns>True if the deprecation check should be performed.</returns>
+        internal static bool ShouldCheck(PackageSpec project, NuGetFramework framework)
+        {
+            if (project.RestoreMetadata == null)
+            {
+                return false;
+            }
+
+            // Gate on SDK analysis level >= 11.0.100
+            if (!SdkAnalysisLevelMinimums.IsEnabled(
+                project.RestoreMetadata.SdkAnalysisLevel,
+                project.RestoreMetadata.UsingMicrosoftNETSdk,
+                SdkAnalysisLevelMinimums.V11_0_100))
+            {
+                return false;
+            }
+
+            // Only check for .NETCoreApp frameworks targeting android with version >= 11.0
+            return StringComparer.OrdinalIgnoreCase.Equals(framework.Framework, FrameworkConstants.FrameworkIdentifiers.NetCoreApp)
+                && framework.Version.Major >= 11
+                && framework.HasPlatform
+                && framework.Platform.Equals("android", StringComparison.OrdinalIgnoreCase);
+        }
+
+        /// <summary>
+        /// Checks whether the given lock file target library uses the deprecated MonoAndroid framework
+        /// by inspecting the paths of compile-time and runtime assemblies.
+        /// </summary>
+        /// <param name="library">The lock file target library to check.</param>
+        /// <returns>True if the library uses MonoAndroid framework assets.</returns>
+        internal static bool UsesMonoAndroidFramework(LockFileTargetLibrary library)
+        {
+            return ContainsMonoAndroidItem(library.CompileTimeAssemblies)
+                || ContainsMonoAndroidItem(library.RuntimeAssemblies);
+        }
+
+        private static bool ContainsMonoAndroidItem(IList<LockFileItem> items)
+        {
+            for (int i = 0; i < items.Count; i++)
+            {
+                string path = items[i].Path;
+
+                // Paths are like "lib/monoandroid10.0/Assembly.dll" or "ref/monoandroid10.0/Assembly.dll"
+                // Extract the framework folder segment (between first and second '/').
+                int firstSlash = path.IndexOf('/');
+                if (firstSlash >= 0)
+                {
+                    int secondSlash = path.IndexOf('/', firstSlash + 1);
+                    if (secondSlash > firstSlash + 1)
+                    {
+                        var folderName = path.AsSpan(firstSlash + 1, secondSlash - firstSlash - 1);
+                        if (folderName.StartsWith("monoandroid".AsSpan(), StringComparison.OrdinalIgnoreCase))
+                        {
+                            return true;
+                        }
+                    }
+                }
+            }
+
+            return false;
+        }
+    }
+}

src/NuGet.Core/NuGet.Commands/Strings.resx

@@ -167,6 +167,11 @@
   <data name="Log_ImportsFallbackWarning" xml:space="preserve">
     <value>Package '{0}' was restored using '{1}' instead of the project target framework '{2}'. This package may not be fully compatible with your project.</value>
   </data>
+  <data name="Warning_MonoAndroidFrameworkDeprecated" xml:space="preserve">
+    <value>Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</value>
+    <comment>{0} - package id
+{1} - package version</comment>
+  </data>
   <data name="Log_CycleDetected" xml:space="preserve">
     <value>Cycle detected.</value>
   </data>

src/NuGet.Core/NuGet.Commands/Utility/SdkAnalysisLevelMinimums.cs

@@ -33,6 +33,14 @@ internal static class SdkAnalysisLevelMinimums
         /// </summary>
         internal static readonly NuGetVersion V10_0_300 = new("10.0.300");
 
+        /// <summary>
+        /// Minimum SDK Analysis Level required for:
+        /// <list type="bullet">
+        /// <item>warning when packages use the deprecated MonoAndroid framework</item>
+        /// </list>
+        /// </summary>
+        internal static readonly NuGetVersion V11_0_100 = new("11.0.100");
+
         /// <summary>
         /// Determines whether the feature is enabled based on the SDK analysis level.
         /// </summary>

src/NuGet.Core/NuGet.Commands/xlf/Strings.cs.xlf

@@ -1486,6 +1486,12 @@ NuGet vyžaduje zdroje HTTPS. Další informace najdete na https://aka.ms/nuget-
         <target state="translated">{0} neposkytuje inkluzivní dolní mez pro závislost {1}. Místo toho bylo přeloženo: {2}.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Warning_MonoAndroidFrameworkDeprecated">
+        <source>Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</source>
+        <target state="new">Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</target>
+        <note>{0} - package id
+{1} - package version</note>
+      </trans-unit>
       <trans-unit id="Warning_PackageWithKnownVulnerability">
         <source>Package '{0}' {1} has a known {2} severity vulnerability, {3}</source>
         <target state="translated">Balíček „{0}“ {1} má známé {2} ohrožení zabezpečení závažnosti, {3}</target>

src/NuGet.Core/NuGet.Commands/xlf/Strings.de.xlf

@@ -1486,6 +1486,12 @@ NuGet erfordert HTTPS-Quellen. Weitere Informationen finden Sie unter https://ak
         <target state="translated">{0} stellt keine inklusive untere Grenze für Abhängigkeiten {1} bereit. {2} wurde stattdessen aufgelöst.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Warning_MonoAndroidFrameworkDeprecated">
+        <source>Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</source>
+        <target state="new">Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</target>
+        <note>{0} - package id
+{1} - package version</note>
+      </trans-unit>
       <trans-unit id="Warning_PackageWithKnownVulnerability">
         <source>Package '{0}' {1} has a known {2} severity vulnerability, {3}</source>
         <target state="translated">Das Paket "{0}" {1} weist eine bekannte {2} Schweregrad-Sicherheitsanfälligkeit auf, {3}.</target>

src/NuGet.Core/NuGet.Commands/xlf/Strings.es.xlf

@@ -1486,6 +1486,12 @@ NuGet requiere orígenes HTTPS. Consulte https://aka.ms/nuget-https-everywhere p
         <target state="translated">{0} no proporciona un límite inferior inclusivo para la dependencia {1}. {2} se resolvió en su lugar.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Warning_MonoAndroidFrameworkDeprecated">
+        <source>Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</source>
+        <target state="new">Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</target>
+        <note>{0} - package id
+{1} - package version</note>
+      </trans-unit>
       <trans-unit id="Warning_PackageWithKnownVulnerability">
         <source>Package '{0}' {1} has a known {2} severity vulnerability, {3}</source>
         <target state="translated">El paquete "{0}" {1} tiene una vulnerabilidad de gravedad {2} conocida, {3}</target>

src/NuGet.Core/NuGet.Commands/xlf/Strings.fr.xlf

@@ -1486,6 +1486,12 @@ NuGet nécessite des sources HTTPS. Reportez-vous à https://aka.ms/nuget-https-
         <target state="translated">{0} ne fournit pas de limite inférieure inclusive pour la dépendance {1}. {2} a été résolu à la place.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Warning_MonoAndroidFrameworkDeprecated">
+        <source>Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</source>
+        <target state="new">Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</target>
+        <note>{0} - package id
+{1} - package version</note>
+      </trans-unit>
       <trans-unit id="Warning_PackageWithKnownVulnerability">
         <source>Package '{0}' {1} has a known {2} severity vulnerability, {3}</source>
         <target state="translated">Le package '{0}' {1} présente une vulnérabilité de gravité {2} connue, {3}.</target>

src/NuGet.Core/NuGet.Commands/xlf/Strings.it.xlf

@@ -1486,6 +1486,12 @@ NuGet richiede origini HTTPS. Vedi https://aka.ms/nuget-https-everywhere per alt
         <target state="translated">In {0} non è specificato un limite inferiore inclusivo per la dipendenza {1}. {2} è stato risolto.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Warning_MonoAndroidFrameworkDeprecated">
+        <source>Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</source>
+        <target state="new">Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</target>
+        <note>{0} - package id
+{1} - package version</note>
+      </trans-unit>
       <trans-unit id="Warning_PackageWithKnownVulnerability">
         <source>Package '{0}' {1} has a known {2} severity vulnerability, {3}</source>
         <target state="translated">Il pacchetto '{0}' {1} presenta una vulnerabilità nota di gravità {2}, {3}</target>

src/NuGet.Core/NuGet.Commands/xlf/Strings.ja.xlf

@@ -1486,6 +1486,12 @@ NuGet には HTTPS ソースが必要です。詳しくは、https://aka.ms/nuge
         <target state="translated">{0} では、依存関係 {1} の下限値 (その値を含む) を指定しませんでした。代わりに、{2} が解決されました。</target>
         <note />
       </trans-unit>
+      <trans-unit id="Warning_MonoAndroidFrameworkDeprecated">
+        <source>Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</source>
+        <target state="new">Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</target>
+        <note>{0} - package id
+{1} - package version</note>
+      </trans-unit>
       <trans-unit id="Warning_PackageWithKnownVulnerability">
         <source>Package '{0}' {1} has a known {2} severity vulnerability, {3}</source>
         <target state="translated">パッケージ '{0}' {1} に既知の {2} 重大度の脆弱性があります、{3}</target>

src/NuGet.Core/NuGet.Commands/xlf/Strings.ko.xlf

@@ -1486,6 +1486,12 @@ NuGet에는 HTTPS 원본이 필요합니다. https://aka.ms/nuget-https-everywhe
         <target state="translated">{0}은(는) 종속성 {1}에 대한 포괄적인 하한을 제공하지 않습니다. 대신 {2}이(가) 확인되었습니다.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Warning_MonoAndroidFrameworkDeprecated">
+        <source>Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</source>
+        <target state="new">Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</target>
+        <note>{0} - package id
+{1} - package version</note>
+      </trans-unit>
       <trans-unit id="Warning_PackageWithKnownVulnerability">
         <source>Package '{0}' {1} has a known {2} severity vulnerability, {3}</source>
         <target state="translated">'{0}' {1} 패키지에 알려진 {2} 심각도 취약성인 {3}이(가) 있습니다.</target>

src/NuGet.Core/NuGet.Commands/xlf/Strings.pl.xlf

@@ -1486,6 +1486,12 @@ Menedżer NuGet wymaga źródeł HTTPS. Aby uzyskać więcej informacji, sprawd
         <target state="translated">{0} nie zapewnia łącznego dolnego ograniczenia dla zależności {1}. {2} został rozwiązany zamiast tego.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Warning_MonoAndroidFrameworkDeprecated">
+        <source>Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</source>
+        <target state="new">Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</target>
+        <note>{0} - package id
+{1} - package version</note>
+      </trans-unit>
       <trans-unit id="Warning_PackageWithKnownVulnerability">
         <source>Package '{0}' {1} has a known {2} severity vulnerability, {3}</source>
         <target state="translated">Pakiet „{0}” {1} ma znane {2} luki w zabezpieczeniach o ważności, {3}</target>

src/NuGet.Core/NuGet.Commands/xlf/Strings.pt-BR.xlf

@@ -1486,6 +1486,12 @@ O NuGet exige fontes HTTPS. Consulte https://aka.ms/nuget-https-everywhere para
         <target state="translated">{0} não fornece um limite inferior inclusivo para a dependência {1}. {2} foi resolvido.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Warning_MonoAndroidFrameworkDeprecated">
+        <source>Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</source>
+        <target state="new">Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</target>
+        <note>{0} - package id
+{1} - package version</note>
+      </trans-unit>
       <trans-unit id="Warning_PackageWithKnownVulnerability">
         <source>Package '{0}' {1} has a known {2} severity vulnerability, {3}</source>
         <target state="translated">O pacote '{0}' {1} tem uma {2} vulnerabilidade de gravidade conhecida, {3}</target>

src/NuGet.Core/NuGet.Commands/xlf/Strings.ru.xlf

@@ -1486,6 +1486,12 @@ NuGet requires HTTPS sources. Refer to https://aka.ms/nuget-https-everywhere for
         <target state="translated">{0} не задает включенную нижнюю границу для зависимости {1}. Использовалась версия {2}.</target>
         <note />
       </trans-unit>
+      <trans-unit id="Warning_MonoAndroidFrameworkDeprecated">
+        <source>Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</source>
+        <target state="new">Package '{0}' {1} uses the deprecated MonoAndroid framework instead of 'net6.0-android' or later. Consider upgrading to a newer version of this package or contacting the package author.</target>
+        <note>{0} - package id
+{1} - package version</note>
+      </trans-unit>
       <trans-unit id="Warning_PackageWithKnownVulnerability">
         <source>Package '{0}' {1} has a known {2} severity vulnerability, {3}</source>
         <target state="translated">У пакета "{0}" {1} есть известная уязвимость {3} (уровень серьезности: {2})</target>