[Xamarin.Android.Build.Tasks] ignore .csproj.user changes (#5283)

I noticed that changing the selected device or emulator in
Visual Studio 2019 16.8 on Windows was causing many MSBuild targets
to run again in the IDE.  The time taken was similar to a `Rebuild`!

Looking closer, I noticed:

	Building target "_CompileJava" completely.
	Input file "App42.csproj.user" is newer than output file "obj\Debug\_javac.stamp".

`.csproj.user` is where the IDE stores the selected device or
emulator.  The contents of the file:

	<?xml version="1.0" encoding="utf-8"?>
	<Project ToolsVersion="Current" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
	  <PropertyGroup>
	    <SelectedDevice>pixel_2_pie_9_0_-_api_28</SelectedDevice>
	    <DefaultDevice>pixel_2_pie_9_0_-_api_28</DefaultDevice>
	  </PropertyGroup>
	</Project>

The reason this triggers many targets is that
[`*.csproj.user` is actually imported][0], which in turn means this
file is automatically included in `$(MSBuildAllProjects)`,
which is used by many `Inputs` of Xamarin.Android MSBuild targets.

I first tried editing `$(MSBuildAllProjects)`, but this property
appears to be readonly, since it is a built-in property in MSBuild.
Attempts at setting it were ignored.

To solve this, create a new `@(_AndroidMSBuildAllProjects)` item
group to be used instead that excludes the `.csproj.user` file.

I was able to reproduce this issue in a new test in
`IncrementalBuildTest`.

TODO:

After this goes in, there is one place in the xamarin/monodroid repo
that needs to use `@(_AndroidMSBuildAllProjects)` instead of
`$(MSBuildAllProjects)`.

[0]: https://github.com/dotnet/msbuild/blob/7452552ce911efdca6aea5a189c409f083db7bc7/src/Tasks/Microsoft.Common.CurrentVersion.targets#L31

Documentation/guides/MSBuildBestPractices.md

@@ -308,6 +308,11 @@ will re-run the target completely. `$(MSBuildAllProjects)` is a list
 of every MSBuild file imported during a build, MSBuild automatically
 evaluates `$(MSBuildAllProjects)` since [MSBuild 16.0][allprojects].
 
+> NOTE: You might consider using `@(_AndroidMSBuildAllProjects)`
+> instead of `$(MSBuildAllProjects)` when working on the
+> Xamarin.Android MSBuild targets. We have excluded the `*.csproj.user`
+> file for performance reasons.
+
 One pitfall, is this `_GenerateDocumentation` example *must* touch the
 timestamps on all files in `Outputs` -- regardless if they were
 actually changed. Otherwise, your target can get into a state where it

Documentation/release-notes/5283.md

@@ -0,0 +1,8 @@
+### Build and deployment performance
+
+  * [GitHub PR 5283](https://github.com/xamarin/xamarin-android/pull/5283):
+    Fixed an issue where changing the selected device or emulator in
+    the IDE would cause many parts of the build to run on an
+    incremental build. This reduced the overall build time from 5.526
+    seconds to 1.451 seconds for this scenario in a small test
+    project.

src/Xamarin.Android.Build.Tasks/MSBuild/Xamarin/Android/Xamarin.Android.Aapt2.targets

@@ -90,7 +90,7 @@ Copyright (C) 2011-2012 Xamarin. All rights reserved.
 </Target>
 
 <Target Name="_ConvertResourcesCases"
-    Inputs="$(MSBuildAllProjects);$(_AndroidBuildPropertiesCache);@(AndroidResource);@(_LibraryResourceDirectories->'%(StampFile)')"
+    Inputs="@(_AndroidMSBuildAllProjects);$(_AndroidBuildPropertiesCache);@(AndroidResource);@(_LibraryResourceDirectories->'%(StampFile)')"
     Outputs="$(_AndroidStampDirectory)_ConvertResourcesCases.stamp"
     DependsOnTargets="_CollectLibraryResourceDirectories;$(_BeforeConvertResourcesCases)"
   >
@@ -116,7 +116,7 @@ Copyright (C) 2011-2012 Xamarin. All rights reserved.
 </Target>
 
 <Target Name="_CompileResources"
-    Inputs="$(MSBuildAllProjects);$(_AndroidBuildPropertiesCache);@(_CompileResourcesInputs)"
+    Inputs="@(_AndroidMSBuildAllProjects);$(_AndroidBuildPropertiesCache);@(_CompileResourcesInputs)"
     Outputs="@(_CompileResourcesInputs->'%(_ArchiveDirectory)%(_FlatFile)')"
     DependsOnTargets="$(_BeforeCompileResources);_ConvertResourcesCases;_CalculateResourceFileName"
   >

src/Xamarin.Android.Build.Tasks/MSBuild/Xamarin/Android/Xamarin.Android.Bindings.ClassParse.targets

@@ -14,7 +14,7 @@ This file is only used by binding projects.
   <UsingTask TaskName="Xamarin.Android.Tasks.ClassParse" AssemblyFile="Xamarin.Android.Build.Tasks.dll" />
 
   <Target Name="_ExportJarToXml"
-      Inputs="@(EmbeddedJar);@(EmbeddedReferenceJar);@(InputJar);@(ReferenceJar);$(MSBuildAllProjects)"
+      Inputs="@(EmbeddedJar);@(EmbeddedReferenceJar);@(InputJar);@(ReferenceJar);@(_AndroidMSBuildAllProjects)"
       Outputs="$(ApiOutputFile)">
     <ItemGroup>
       <_AndroidDocumentationPath Include="@(JavaDocIndex->'%(RootDir)\%(Directory)')" />

src/Xamarin.Android.Build.Tasks/MSBuild/Xamarin/Android/Xamarin.Android.Bindings.Core.targets

@@ -47,7 +47,7 @@ It is shared between "legacy" binding projects and .NET 5 projects.
   <Target Name="GenerateBindings"
       Condition=" '$(UsingAndroidNETSdk)' != 'true' Or '@(InputJar->Count())' != '0' Or '@(EmbeddedJar->Count())' != '0' Or '@(LibraryProjectZip->Count())' != '0' "
       DependsOnTargets="ExportJarToXml;_ResolveMonoAndroidSdks"
-      Inputs="$(ApiOutputFile);@(TransformFile);@(ReferencePath);@(ReferenceDependencyPaths);$(MSBuildAllProjects)"
+      Inputs="$(ApiOutputFile);@(TransformFile);@(ReferencePath);@(ReferenceDependencyPaths);@(_AndroidMSBuildAllProjects)"
       Outputs="$(_GeneratorStampFile)">
 
     <!-- Delete previous generated files if they still exist -->

src/Xamarin.Android.Build.Tasks/MSBuild/Xamarin/Android/Xamarin.Android.Bindings.JarToXml.targets

@@ -14,7 +14,7 @@ This file is only used by binding projects.
   <UsingTask TaskName="Xamarin.Android.Tasks.JarToXml" AssemblyFile="Xamarin.Android.Build.Tasks.dll" />
 
   <Target Name="_ExportJarToXml"
-      Inputs="@(EmbeddedJar);@(EmbeddedReferenceJar);@(InputJar);@(ReferenceJar);$(MSBuildAllProjects)"
+      Inputs="@(EmbeddedJar);@(EmbeddedReferenceJar);@(InputJar);@(ReferenceJar);@(_AndroidMSBuildAllProjects)"
       Outputs="$(ApiOutputFile)">
     <JarToXml
         JavaMaximumHeapSize="$(JavaMaximumHeapSize)"

src/Xamarin.Android.Build.Tasks/MSBuild/Xamarin/Android/Xamarin.Android.Designer.targets

@@ -142,7 +142,7 @@ Copyright (C) 2016 Xamarin. All rights reserved.
 
 <Target Name="SetupDependenciesForDesigner"
     DependsOnTargets="UpdateAndroidResources;_AdjustJavacVersionArguments;_GeneratePackageManagerJavaForDesigner;_GetMonoPlatformJarPath;_DetermineJavaLibrariesToCompile"
-    Inputs="$(MSBuildAllProjects);$(MonoPlatformJarPath);@(_JavaStubFiles);@(AndroidJavaSource)"
+    Inputs="@(_AndroidMSBuildAllProjects);$(MonoPlatformJarPath);@(_JavaStubFiles);@(AndroidJavaSource)"
     Outputs="$(_AndroidStampDirectory)SetupDependenciesForDesigner.stamp">
   <Javac
       JavaPlatformJarPath="$(JavaPlatformJarPath)"

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.BuildOrder.targets

@@ -15,6 +15,7 @@ projects, these properties are set in Xamarin.Android.Legacy.targets.
     <BuildDependsOn>
       _ValidateLinkMode;
       _CheckNonIdealConfigurations;
+      _SetupMSBuildAllProjects;
       _SetupDesignTimeBuildForBuild;
       _CategorizeAndroidLibraries;
       _CreatePropertiesCache;
@@ -70,6 +71,7 @@ projects, these properties are set in Xamarin.Android.Legacy.targets.
   <PropertyGroup Condition=" '$(AndroidApplication)' != 'True' ">
     <BuildDependsOn>
       _ValidateLinkMode;
+      _SetupMSBuildAllProjects;
       _SetupDesignTimeBuildForBuild;
       _CategorizeAndroidLibraries;
       _CreatePropertiesCache;
@@ -115,6 +117,7 @@ projects, these properties are set in Xamarin.Android.Legacy.targets.
       $([MSBuild]::Unescape($(CoreBuildDependsOn.Replace('IncrementalClean;', '$(_BeforeIncrementalClean);IncrementalClean;'))))
     </CoreBuildDependsOn>
     <CompileDependsOn>
+      _SetupMSBuildAllProjects;
       _SetupDesignTimeBuildForCompile;
       _AddAndroidDefines;
       _IncludeLayoutBindingSources;

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/IncrementalBuildTest.cs

@@ -673,6 +673,29 @@ public void LinkAssembliesNoShrink ()
 			}
 		}
 
+		[Test]
+		public void CSProjUserFileChanges ()
+		{
+			var proj = new XamarinAndroidApplicationProject ();
+			var selectedDevice = "foo";
+			var csproj_user_file = $"{proj.ProjectName}.csproj.user";
+			proj.Sources.Add (new BuildItem.NoActionResource (csproj_user_file) {
+				TextContent = () => $"<Project><PropertyGroup><SelectedDevice>{selectedDevice}</SelectedDevice></PropertyGroup></Project>"
+			});
+			using (var b = CreateApkBuilder ()) {
+				Assert.IsTrue (b.Build (proj), "first build should have succeeded.");
+
+				// Simulates a different device/emulator selection in the IDE
+				selectedDevice = "bar";
+				proj.Touch (csproj_user_file);
+
+				Assert.IsTrue (b.Build (proj), "second build should have succeeded.");
+				b.Output.AssertTargetIsSkipped ("_CompileJava");
+				b.Output.AssertTargetIsSkipped ("_CompileToDalvik");
+				b.Output.AssertTargetIsSkipped ("_Sign");
+			}
+		}
+
 		[Test]
 		[NonParallelizable] // /restore can fail on Mac in parallel
 		public void ConvertCustomView ([Values (true, false)] bool useAapt2)

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

@@ -819,7 +819,7 @@ because xbuild doesn't support framework reference assemblies.
 </Target>
 
 <Target Name="_GenerateAndroidAssetsDir"
-	Inputs="$(MSBuildAllProjects);@(_AndroidResolvedAssets)"
+	Inputs="@(_AndroidMSBuildAllProjects);@(_AndroidResolvedAssets)"
 	Outputs="@(_AndroidAssetsDest)">
 	<MakeDir Directories="$(MonoAndroidAssetsDirIntermediate)" />
 	<Copy SourceFiles="@(_AndroidResolvedAssets)" DestinationFiles="@(_AndroidAssetsDest)" SkipUnchangedFiles="true" />
@@ -924,7 +924,7 @@ because xbuild doesn't support framework reference assemblies.
 <Target Name="_BeforeManagedUpdateAndroidResgen">
   <PropertyGroup>
     <_ManagedUpdateAndroidResgenInputs>
-      $(MSBuildAllProjects);
+      @(_AndroidMSBuildAllProjects);
       @(AndroidResource);
       @(AndroidBoundLayout);
       @(_MonoAndroidReferencePath);
@@ -1007,7 +1007,7 @@ because xbuild doesn't support framework reference assemblies.
 </Target>
 
 <Target Name="_GenerateAndroidResourceDir"
-	Inputs="$(MSBuildProjectFullPath);$(MSBuildAllProjects);@(_AndroidResolvedResources);$(_AndroidBuildPropertiesCache)"
+	Inputs="$(MSBuildProjectFullPath);@(_AndroidMSBuildAllProjects);@(_AndroidResolvedResources);$(_AndroidBuildPropertiesCache)"
 	Outputs="$(_AndroidResFlagFile)"
 	DependsOnTargets="$(_OnResolveMonoAndroidSdks)">
 	<CheckForInvalidResourceFileNames
@@ -1147,7 +1147,7 @@ because xbuild doesn't support framework reference assemblies.
 		_DefineBuildTargetAbis;
 	</_UpdateAndroidResgenDependsOnTargets>
 	<_UpdateAndroidResgenInputs>
-		$(MSBuildAllProjects);
+		@(_AndroidMSBuildAllProjects);
 		@(_AndroidResourceDest);
 		$(_AndroidBuildPropertiesCache);
 		$(ProjectAssetsFile);
@@ -1379,7 +1379,7 @@ because xbuild doesn't support framework reference assemblies.
 
 <Target Name="_GenerateJavaStubs"
     DependsOnTargets="$(_GenerateJavaStubsDependsOnTargets);$(BeforeGenerateAndroidManifest)"
-    Inputs="$(MSBuildAllProjects);@(_ResolvedUserMonoAndroidAssemblies);$(_AndroidManifestAbs);$(_AndroidBuildPropertiesCache)"
+    Inputs="@(_AndroidMSBuildAllProjects);@(_ResolvedUserMonoAndroidAssemblies);$(_AndroidManifestAbs);$(_AndroidBuildPropertiesCache)"
     Outputs="$(_AndroidStampDirectory)_GenerateJavaStubs.stamp">
 
   <PropertyGroup>
@@ -1432,7 +1432,7 @@ because xbuild doesn't support framework reference assemblies.
 
 <Target Name="_ManifestMerger"
     Condition=" '$(AndroidManifestMerger)' == 'manifestmerger.jar' "
-    Inputs="$(IntermediateOutputPath)AndroidManifest.xml;@(ExtractedManifestDocuments);$(_AndroidBuildPropertiesCache);$(MSBuildAllProjects)"
+    Inputs="$(IntermediateOutputPath)AndroidManifest.xml;@(ExtractedManifestDocuments);$(_AndroidBuildPropertiesCache);@(_AndroidMSBuildAllProjects)"
     Outputs="$(IntermediateOutputPath)android\AndroidManifest.xml"
   >
   <ManifestMerger
@@ -1530,7 +1530,7 @@ because xbuild doesn't support framework reference assemblies.
 
 <Target Name="_GeneratePackageManagerJava"
   DependsOnTargets="$(_GeneratePackageManagerJavaDependsOn)"
-  Inputs="$(MSBuildAllProjects);$(_ResolvedUserAssembliesHashFile);$(MSBuildProjectFile);$(_AndroidBuildPropertiesCache);@(AndroidEnvironment);@(LibraryEnvironments)"
+  Inputs="@(_AndroidMSBuildAllProjects);$(_ResolvedUserAssembliesHashFile);$(MSBuildProjectFile);$(_AndroidBuildPropertiesCache);@(AndroidEnvironment);@(LibraryEnvironments)"
   Outputs="$(_AndroidStampDirectory)_GeneratePackageManagerJava.stamp">
   <!-- Create java needed for Mono runtime -->
   <GeneratePackageManagerJava
@@ -1576,7 +1576,7 @@ because xbuild doesn't support framework reference assemblies.
   <PropertyGroup>
     <_CreateBaseApkInputs>
       $(_CreateBaseApkInputs);
-      $(MSBuildAllProjects);
+      @(_AndroidMSBuildAllProjects);
       $(IntermediateOutputPath)android\AndroidManifest.xml;
       @(_ModifiedResources);
       @(_AndroidAssetsDest);
@@ -1703,7 +1703,7 @@ because xbuild doesn't support framework reference assemblies.
 
 <Target Name="_CompileJava"
   DependsOnTargets="$(_CompileJavaDependsOnTargets)"
-  Inputs="$(MSBuildAllProjects);$(MonoPlatformJarPath);@(_JavaStubFiles);@(AndroidJavaSource)"
+  Inputs="@(_AndroidMSBuildAllProjects);$(MonoPlatformJarPath);@(_JavaStubFiles);@(AndroidJavaSource)"
   Outputs="$(IntermediateOutputPath)_javac.stamp">
 
   <!-- remove existing <Javac /> outputs, since *.class files and classes.zip could contain old files -->
@@ -1758,7 +1758,7 @@ because xbuild doesn't support framework reference assemblies.
 		_CalculateProguardConfigurationFiles;
 	</_CompileToDalvikDependsOnTargets>
 	<_CompileToDalvikInputs>
-		$(MSBuildAllProjects)
+		@(_AndroidMSBuildAllProjects)
 		;@(_JavaLibrariesToCompileForApp)
 		;@(AndroidExternalJavaLibrary)
 		;$(_AndroidIntermediateClassesZip)
@@ -1982,7 +1982,7 @@ because xbuild doesn't support framework reference assemblies.
 
 <PropertyGroup>
 	<_BuildApkEmbedInputs>
-		$(MSBuildAllProjects)
+		@(_AndroidMSBuildAllProjects)
 		;$(_PackagedResources)
 		;@(_ShrunkAssemblies)
 		;@(AndroidNativeLibrary)
@@ -2285,7 +2285,7 @@ because xbuild doesn't support framework reference assemblies.
 <Target Name="_PrepareForSign">
   <PropertyGroup Condition=" '$(AndroidPackageFormat)' == 'aab' ">
     <_SignInputs>
-      $(MSBuildAllProjects);
+      @(_AndroidMSBuildAllProjects);
       $(_AndroidBuildPropertiesCache);
       $(_AppBundleIntermediate);
     </_SignInputs>
@@ -2295,7 +2295,7 @@ because xbuild doesn't support framework reference assemblies.
   </PropertyGroup>
   <PropertyGroup Condition=" '$(AndroidPackageFormat)' != 'aab' ">
     <_SignInputs>
-      $(MSBuildAllProjects);
+      @(_AndroidMSBuildAllProjects);
       $(_AndroidBuildPropertiesCache);
       $(ApkFileIntermediate);
     </_SignInputs>

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

@@ -26,6 +26,12 @@ This file is used by all project types, including binding projects.
     />
   </Target>
 
+  <Target Name="_SetupMSBuildAllProjects">
+    <ItemGroup>
+      <_AndroidMSBuildAllProjects Include="$(MSBuildAllProjects)" Exclude="$(MSBuildProjectFullPath).user" />
+    </ItemGroup>
+  </Target>
+
   <Target Name="_SetupDesignTimeBuildForBuild" DependsOnTargets="_CreateStampDirectory">
     <PropertyGroup>
       <DesignTimeBuild Condition=" '$(DesignTimeBuild)' == '' ">false</DesignTimeBuild>

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

@@ -27,6 +27,7 @@ projects. .NET 5 projects will not import this file.
     <BuildDependsOn>
       _ValidateLinkMode;
       _CheckNonIdealConfigurations;
+      _SetupMSBuildAllProjects;
       _SetupDesignTimeBuildForBuild;
       _CreatePropertiesCache;
       _CleanIntermediateIfNeeded;
@@ -58,6 +59,7 @@ projects. .NET 5 projects will not import this file.
   <PropertyGroup Condition=" '$(AndroidApplication)' != 'True' And '$(_AndroidIsBindingProject)' != 'True' ">
     <BuildDependsOn>
       _ValidateLinkMode;
+      _SetupMSBuildAllProjects;
       _SetupDesignTimeBuildForBuild;
       _CreatePropertiesCache;
       _CleanIntermediateIfNeeded;
@@ -82,6 +84,7 @@ projects. .NET 5 projects will not import this file.
       $([MSBuild]::Unescape($(CoreBuildDependsOn.Replace('IncrementalClean;', '$(_BeforeIncrementalClean);IncrementalClean;'))))
     </CoreBuildDependsOn>
     <CompileDependsOn>
+      _SetupMSBuildAllProjects;
       _SetupDesignTimeBuildForCompile;
       _AddAndroidDefines;
       _IncludeLayoutBindingSources;
@@ -162,13 +165,15 @@ projects. .NET 5 projects will not import this file.
 
   <PropertyGroup Condition=" '$(_AndroidIsBindingProject)' == 'True' ">
     <BuildDependsOn>
+      _SetupMSBuildAllProjects;
       _SetupDesignTimeBuildForBuild;
       AddLibraryJarsToBind;
       $(BuildDependsOn);
       BuildDocumentation;
     </BuildDependsOn>
 
     <CompileDependsOn>
+      _SetupMSBuildAllProjects;
       _SetupDesignTimeBuildForCompile;
       AddLibraryJarsToBind;
       $(CompileDependsOn);