[msbuild] Improve the error message when the SupportedOSPlatformVersion is lower than the minimum. Fixes #21368.

dotnet/generate-target-platforms.csharp

@@ -50,6 +50,7 @@ using (TextWriter writer = new StreamWriter (outputPath)) {
 	writer.WriteLine ("\t</ItemGroup>");
 	writer.WriteLine ("\t<PropertyGroup>");
 	writer.WriteLine ($"\t\t<{platform}MinSupportedOSPlatformVersion>{minSdkVersionString}</{platform}MinSupportedOSPlatformVersion>");
+	writer.WriteLine ($"\t\t<MinSupportedOSPlatformVersion>$({platform}MinSupportedOSPlatformVersion)</MinSupportedOSPlatformVersion>");
 	writer.WriteLine ("\t</PropertyGroup>");
 	writer.WriteLine ("</Project>");
 }

msbuild/Xamarin.Localization.MSBuild/MSBStrings.resx

@@ -1563,6 +1563,19 @@
         <comment>RuntimeIdentifier: don't translate (it's the name of a MSBuild property)</comment>
     </data>
 
+    <data name="E7125" xml:space="preserve">
+        <value>Unable to parse the value '{0}' for the property '{1}.</value>
+        <comment>
+            {0}: user-provided value
+            {1}: name of an MSBuild property
+        </comment>
+    </data>
+
+    <data name="E7126" xml:space="preserve">
+        <value>The SupportedOSPlatformVersion value '{0}' in the project file is lower than the minimum value '{1}'.</value>
+        <comment>SupportedOSPlatformVersion: don't translate (it's the name of an MSBuild property)</comment>
+    </data>
+
     <data name="XcodeBuild_CreateNativeRef" xml:space="preserve">
         <value>Adding reference to Xcode project output: '{0}'. The '%(CreateNativeReference)' metadata can be set to 'false' to opt out of this behavior.</value>
         <comment>

msbuild/Xamarin.MacDev.Tasks/Tasks/CompileAppManifest.cs

@@ -62,6 +62,9 @@ public class CompileAppManifest : XamarinTask, ITaskCallback, ICancelableTask {
 
 		public bool IsWatchExtension { get; set; }
 
+		[Required]
+		public string MinSupportedOSPlatformVersion { get; set; } = string.Empty;
+
 		public ITaskItem [] PartialAppManifests { get; set; } = Array.Empty<ITaskItem> ();
 
 		[Required]
@@ -302,6 +305,18 @@ bool SetMinimumOSVersion (PDictionary plist)
 				minimumOSVersion = minimumOSVersionInManifest!;
 			}
 
+			// Verify that the value is not lower than the minimum
+			if (!Version.TryParse (MinSupportedOSPlatformVersion, out var minSupportedVersion)) {
+				Log.LogError (MSBStrings.E7125 /* Unable to parse the value '{0}' for the property '{1}. */, MinSupportedOSPlatformVersion, "MinSupportedOSPlatformVersion");
+				return false;
+			} else if (!Version.TryParse (SupportedOSPlatformVersion, out var supportedVersion)) {
+				Log.LogError (MSBStrings.E7125 /* Unable to parse the value '{0}' for the property '{1}. */, SupportedOSPlatformVersion, "SupportedOSPlatformVersion");
+				return false;
+			} else if (minSupportedVersion > supportedVersion) {
+				Log.LogError (MSBStrings.E7126 /* The SupportedOSPlatformVersion value '{0}' in the project file is lower than the minimum value '{1}'." */, SupportedOSPlatformVersion, MinSupportedOSPlatformVersion);
+				return false;
+			}
+
 			// Write out our value
 			plist [minimumVersionKey] = minimumOSVersion;
 

msbuild/Xamarin.Shared/Xamarin.Shared.targets

@@ -570,6 +570,7 @@ Copyright (C) 2018 Microsoft. All rights reserved.
 			IsWatchApp="$(IsWatchApp)"
 			IsWatchExtension="$(IsWatchExtension)"
 			IsXPCService="$(IsXPCService)"
+			MinSupportedOSPlatformVersion="$(MinSupportedOSPlatformVersion)"
 			PartialAppManifests="@(PartialAppManifest)"
 			ProjectDir="$(MSBuildProjectDirectory)"
 			ResourcePrefix="$(_ResourcePrefix)"

tests/Makefile

@@ -88,6 +88,7 @@ test.config: Makefile $(TOP)/Make.config $(TOP)/mk/mono.mk $(TOP)/eng/Version.De
 	@printf "ENABLE_XAMARIN=$(ENABLE_XAMARIN)\n" >> $@
 	@printf "XCODE_IS_STABLE=$(XCODE_IS_STABLE)\n" >> $@
 	@printf "XCODE_VERSION=$(XCODE_VERSION)\n" >> $@
+	@printf "$(foreach platform,$(DOTNET_PLATFORMS_UPPERCASE),DOTNET_MIN_$(platform)_SDK_VERSION=$(DOTNET_MIN_$(platform)_SDK_VERSION)\\n)" | sed 's/^ //' >> $@
 
 test-system.config: Makefile $(TOP)/Make.config $(TOP)/mk/mono.mk $(TOP)/eng/Version.Details.xml
 	@rm -f $@
@@ -122,6 +123,7 @@ test-system.config: Makefile $(TOP)/Make.config $(TOP)/mk/mono.mk $(TOP)/eng/Ver
 	@printf "ENABLE_XAMARIN=$(ENABLE_XAMARIN)\n" >> $@
 	@printf "XCODE_IS_STABLE=$(XCODE_IS_STABLE)\n" >> $@
 	@printf "XCODE_VERSION=$(XCODE_VERSION)\n" >> $@
+	@printf "$(foreach platform,$(DOTNET_PLATFORMS_UPPERCASE),DOTNET_MIN_$(platform)_SDK_VERSION=$(DOTNET_MIN_$(platform)_SDK_VERSION)\\n)" | sed 's/^ //' >> $@
 
 clean-local::
 	$(Q) $(SYSTEM_XBUILD) /t:Clean /p:Platform=iPhoneSimulator /p:Configuration=$(CONFIG) $(XBUILD_VERBOSITY) tests.sln

tests/dotnet/UnitTests/ProjectTest.cs

@@ -1861,7 +1861,7 @@ public void UnsupportedTargetPlatformVersion (ApplePlatform platform)
 			// Pick a target platform version that we don't really support,
 			// but don't show an error in .NET 8 because of backwards compat.
 			// The earliest target OS version should do.
-			var minSupportedOSVersion = GetSupportedTargetPlatformVersions (platform).First ();
+			var minSupportedOSVersion = GetMinSupportedOSPlatformVersion (platform);
 			var targetFrameworks = Configuration.DotNetTfm + "-" + platform.AsString ().ToLowerInvariant () + minSupportedOSVersion;
 			var supportedApiVersions = GetSupportedApiVersions (platform, isCompat: false);
 
@@ -1914,6 +1914,11 @@ string [] GetSupportedTargetPlatformVersions (ApplePlatform platform)
 				.ToArray ();
 		}
 
+		string GetMinSupportedOSPlatformVersion (ApplePlatform platform)
+		{
+			return Configuration.GetVariable ($"DOTNET_MIN_{platform.AsString ().ToUpperInvariant ()}_SDK_VERSION", "unknown MinSupportedOSPlatformVersion");
+		}
+
 		[Test]
 		[TestCase (ApplePlatform.MacCatalyst, "MtouchArch", "x86_64")]
 		[TestCase (ApplePlatform.iOS, "MtouchArch", "ARMv7s")]
@@ -2837,5 +2842,26 @@ static HashSet<string> GetLinkedWithFrameworks (string path)
 			}
 			return rv;
 		}
+
+		[Test]
+		[TestCase (ApplePlatform.MacCatalyst, "maccatalyst-x64", "13.1")]
+		[TestCase (ApplePlatform.iOS, "ios-arm64", "10.0")]
+		[TestCase (ApplePlatform.TVOS, "tvossimulator-x64", "10.0")]
+		[TestCase (ApplePlatform.MacOSX, "osx-arm64", "10.0")]
+		public void InvalidSupportedOSPlatformVersion (ApplePlatform platform, string runtimeIdentifiers, string version)
+		{
+			var project = "MySimpleApp";
+			Configuration.IgnoreIfIgnoredPlatform (platform);
+			Configuration.AssertRuntimeIdentifiersAvailable (platform, runtimeIdentifiers);
+
+			var minVersion = GetMinSupportedOSPlatformVersion (platform);
+			var project_path = GetProjectPath (project, runtimeIdentifiers: runtimeIdentifiers, platform: platform, out var appPath);
+			Clean (project_path);
+			var properties = GetDefaultProperties (runtimeIdentifiers);
+			properties ["SupportedOSPlatformVersion"] = version;
+			var rv = DotNet.AssertBuildFailure (project_path, properties);
+			var errors = BinLog.GetBuildLogErrors (rv.BinLogPath).ToArray ();
+			AssertErrorMessages (errors, $"The SupportedOSPlatformVersion value '{version}' in the project file is lower than the minimum value '{minVersion}'.");
+		}
 	}
 }