[Xamarin.Android.Build.Tasks] downgrade d8/r8 warning messages to `…

…info` (#7643)

Fixes: dotnet/maui#10901

Context: https://r8.googlesource.com/r8/+/refs/tags/3.3.75/src/main/java/com/android/tools/r8/BaseCompilerCommandParser.java#246

Building a .NET MAUI project such as:

	dotnet new maui
	dotnet build -c Release -f net6.0-android -p:AndroidLinkMode=r8

Results in build warnings from R8 such as:

	R8 : warning : Missing class androidx.window.extensions.WindowExtensions

In 92bc705, we already had attempted to silence warnings from R8:

	R8 : warning : Resource 'META-INF/MANIFEST.MF' already exists.

At the time, there was no option to hide warnings, but now there is!

	--map-diagnostics[:<type>] <from-level> <to-level>
	    # Map diagnostics of <type> (default any) reported as
	    # <from-level> to <to-level> where <from-level> and
	    # <to-level> are one of 'info', 'warning', or 'error' and the
	    # optional <type> is either the simple or fully qualified
	    # Java type name of a diagnostic. If <type> is unspecified,
	    # all diagnostics at <from-level> will be mapped.
	    # Note that fatal compiler errors cannot be mapped.

We can pass:

	--map-diagnostics warning info

Which can be done in existing apps via:

	<AndroidD8ExtraArguments>--map-diagnostics warning info</AndroidD8ExtraArguments>
	<AndroidR8ExtraArguments>--map-diagnostics warning info</AndroidR8ExtraArguments>

To solve this problem, let's create a new `$(AndroidD8IgnoreWarnings)`
MSBuild property and make use of one we already have
`$(AndroidR8IgnoreWarnings)`:

	<ItemGroup>
	  <_AndroidD8MapDiagnostics Condition=" '$(AndroidD8IgnoreWarnings)' == 'true' " Include="warning" To="info" />
	  <_AndroidR8MapDiagnostics Condition=" '$(AndroidR8IgnoreWarnings)' == 'true' " Include="warning" To="info" />
	</ItemGroup>

We can then use these item groups to pass `--map-diagnostics` as
appropriate.  Developers can turn off either property to disable this
behavior.

We can then remove the weird `Regex` code added in 92bc705.
The existing tests from 92bc705 should also be sufficient for
testing this change.

Documentation/guides/building-apps/build-properties.md

@@ -1110,6 +1110,14 @@ or use `-p:AndroidCreateProguardMappingFile=False` on the command line.
 
 This property was added in Xamarin.Android 11.2.
 
+## AndroidD8IgnoreWarnings
+
+Specifies `--map-diagnostics warning info` to be passed to `d8`. The
+default value is `True`, but can be set to `False` to enforce more
+strict behavior. See the [D8 and R8 source code][r8-source] for details.
+
+Added in .NET 8.
+
 ## AndroidR8IgnoreWarnings
 
 Specifies
@@ -1118,8 +1126,13 @@ to continue with dex compilation even if certain warnings are
 encountered. The default value is `True`, but can be set to `False` to
 enforce more strict behavior. See the [ProGuard manual](https://www.guardsquare.com/manual/configuration/usage) for details.
 
+Starting in .NET 8, specifies `--map-diagnostics warning info`. See
+the [D8 and R8 source code][r8-source] for details.
+
 Added in Xamarin.Android 10.3.
 
+[r8-source]: https://r8.googlesource.com/r8/+/refs/tags/3.3.75/src/main/java/com/android/tools/r8/BaseCompilerCommandParser.java#246
+
 ## AndroidR8JarPath
 
 The path to `r8.jar` for use with the

src/Xamarin.Android.Build.Tasks/Tasks/D8.cs

@@ -2,7 +2,6 @@
 using Microsoft.Build.Utilities;
 using System.Collections.Generic;
 using System.IO;
-using System.Text.RegularExpressions;
 using Xamarin.Android.Tools;
 using Microsoft.Android.Build.Tasks;
 
@@ -39,6 +38,7 @@ public class D8 : JavaToolTask
 		public ITaskItem [] JavaLibrariesToEmbed { get; set; }
 		public ITaskItem [] AlternativeJarLibrariesToEmbed { get; set; }
 		public ITaskItem [] JavaLibrariesToReference { get; set; }
+		public ITaskItem [] MapDiagnostics { get; set; }
 
 		public string ExtraArguments { get; set; }
 
@@ -110,22 +110,19 @@ protected virtual CommandLineBuilder GetCommandLineBuilder ()
 			foreach (var jar in injars)
 				cmd.AppendFileNameIfNotNull (jar);
 
-			return cmd;
-		}
-
-		/// <summary>
-		/// r8 tends to print:
-		/// Warning: Resource 'META-INF/MANIFEST.MF' already exists.
-		/// </summary>
-		static readonly Regex resourceWarning = new Regex ("Warning: Resource.+already exists", RegexOptions.IgnoreCase | RegexOptions.Compiled);
-
-		protected override void LogEventsFromTextOutput (string singleLine, MessageImportance messageImportance)
-		{
-			if (resourceWarning.IsMatch (singleLine)) {
-				Log.LogMessage (messageImportance, singleLine);
-			} else {
-				base.LogEventsFromTextOutput (singleLine, messageImportance);
+			if (MapDiagnostics != null) {
+				foreach (var diagnostic in MapDiagnostics) {
+					var from = diagnostic.ItemSpec;
+					var to = diagnostic.GetMetadata ("To");
+					if (string.IsNullOrEmpty (from) || string.IsNullOrEmpty (to))
+						continue;
+					cmd.AppendSwitch ("--map-diagnostics");
+					cmd.AppendSwitch (from);
+					cmd.AppendSwitch (to);
+				}
 			}
+
+			return cmd;
 		}
 	}
 }

src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets

@@ -261,6 +261,7 @@ Copyright (C) 2011-2012 Xamarin. All rights reserved.
 	<AndroidEnableProguard Condition=" '$(AndroidLinkTool)' != '' ">True</AndroidEnableProguard>
 	<AndroidEnableDesugar  Condition=" '$(AndroidEnableDesugar)' == '' And ('$(AndroidDexTool)' == 'd8' Or '$(AndroidLinkTool)' == 'r8') ">True</AndroidEnableDesugar>
 	<AndroidEnableDesugar  Condition=" '$(AndroidEnableDesugar)' == '' ">False</AndroidEnableDesugar>
+	<AndroidD8IgnoreWarnings    Condition=" '$(AndroidD8IgnoreWarnings)' == '' ">True</AndroidD8IgnoreWarnings>
 	<AndroidR8IgnoreWarnings    Condition=" '$(AndroidR8IgnoreWarnings)' == '' ">True</AndroidR8IgnoreWarnings>
 	<AndroidCreateProguardMappingFile Condition="'$(AndroidCreateProguardMappingFile)' == '' And '$(AndroidLinkTool)' == 'r8'">True</AndroidCreateProguardMappingFile>
 

src/Xamarin.Android.Build.Tasks/Xamarin.Android.D8.targets

@@ -48,6 +48,11 @@ Copyright (C) 2018 Xamarin. All rights reserved.
         Condition=" '$(AndroidLinkTool)' != '' "
     />
 
+    <ItemGroup>
+      <_AndroidD8MapDiagnostics Condition=" '$(AndroidD8IgnoreWarnings)' == 'true' " Include="warning" To="info" />
+      <_AndroidR8MapDiagnostics Condition=" '$(AndroidR8IgnoreWarnings)' == 'true' " Include="warning" To="info" />
+    </ItemGroup>
+
     <R8
         Condition=" '$(_UseR8)' == 'True' "
         ToolPath="$(JavaToolPath)"
@@ -77,6 +82,7 @@ Copyright (C) 2018 Xamarin. All rights reserved.
         ExtraArguments="$(AndroidR8ExtraArguments)"
         IntermediateOutputPath="$(IntermediateOutputPath)"
         AssemblyIdentityMapFile="$(_AndroidLibrayProjectAssemblyMapFile)"
+        MapDiagnostics="@(_AndroidR8MapDiagnostics)"
     />
     <D8
         Condition=" '$(_UseR8)' != 'True' "
@@ -96,6 +102,7 @@ Copyright (C) 2018 Xamarin. All rights reserved.
         ExtraArguments="$(AndroidD8ExtraArguments)"
         IntermediateOutputPath="$(IntermediateOutputPath)"
         AssemblyIdentityMapFile="$(_AndroidLibrayProjectAssemblyMapFile)"
+        MapDiagnostics="@(_AndroidD8MapDiagnostics)"
     />
 
     <Touch Files="$(_AndroidStampDirectory)_CompileToDalvik.stamp" AlwaysCreate="true" />