Add analyzer bootstrap phase (#2540)

The existing integration test build will now also use the live analyzer built first.

build.cmd

@@ -1,2 +1,2 @@
 @echo off
-powershell -ExecutionPolicy ByPass -NoProfile -command "& """%~dp0eng\common\Build.ps1""" -restore -build %*"
+powershell -ExecutionPolicy ByPass -NoProfile -command "& """%~dp0eng\Build.ps1""" -restore -build %*"

eng/Analyzers.props

@@ -4,4 +4,16 @@
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.CodeStyle" Version="$(MicrosoftCodeAnalysisCSharpCodeStyleVersion)" PrivateAssets="all" />
     <!-- <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.205" PrivateAssets="all" /> -->
   </ItemGroup>
+
+  <Import Project="$(BootstrapBuildPath)/Microsoft.NET.ILLink.Analyzers.props" Condition="'$(BootstrapBuildPath)' != ''" />
+
+  <!-- Don't enable for Cecil, as they can't be suppressed -->
+  <PropertyGroup Condition="'$(BootstrapBuildPath)' != '' and '$(MSBuildProjectName)' != 'Mono.Cecil.Pdb'">
+    <EnableTrimAnalyzer>true</EnableTrimAnalyzer>
+  </PropertyGroup>
+
+  <ItemGroup Condition="'$(BootstrapBuildPath)' != ''">
+    <Analyzer Include="$(BootstrapBuildPath)/ILLink.RoslynAnalyzer.dll" />
+  </ItemGroup>
+
 </Project>

eng/bootstrap.proj

@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.DotNet.Arcade.Sdk">
+
+    <Target Name="Build">
+        <MSBuild Projects="../src/ILLink.RoslynAnalyzer/ILLink.RoslynAnalyzer.csproj"
+                 Targets="Restore" />
+        <MSBuild Projects="../src/ILLink.RoslynAnalyzer/ILLink.RoslynAnalyzer.csproj"
+                 Properties="OutDir=$(ArtifactsDir)/bootstrap"
+                 Targets="Build" />
+    </Target>
+</Project>

eng/build.ps1

@@ -0,0 +1,17 @@
+[CmdletBinding(PositionalBinding=$false)]
+Param(
+  [switch] $integrationTest,
+  [Parameter(ValueFromRemainingArguments=$true)][String[]]$remaining
+)
+
+. (Join-Path $PSScriptRoot "common/tools.ps1")
+
+$args = $remaining.Clone()
+
+if ($integrationTest) {
+    dotnet build (Join-Path $PSScriptRoot bootstrap.proj)
+    $args += "-integrationTest"
+    $args += "/p:BootstrapBuildPath=$ArtifactsDir/bootstrap"
+}
+
+powershell -ExecutionPolicy ByPass -NoProfile (Join-Path $PSScriptRoot "common/build.ps1") @args

src/ILLink.RoslynAnalyzer/RequiresAnalyzerBase.cs

@@ -175,10 +175,10 @@ namespace ILLink.RoslynAnalyzer
 					for (int i = 0; i < typeParams.Length; i++) {
 						var typeParam = typeParams[i];
 						var typeArg = typeArgs[i];
-						if (!typeParam.HasConstructorConstraint)
+						if (!typeParam.HasConstructorConstraint ||
+							typeArg is not INamedTypeSymbol { InstanceConstructors: { } typeArgCtors })
 							continue;
 
-						var typeArgCtors = ((INamedTypeSymbol) typeArg).InstanceConstructors;
 						foreach (var instanceCtor in typeArgCtors) {
 							if (instanceCtor.Arity > 0)
 								continue;

src/linker/Linker.Steps/OutputStep.cs

@@ -174,8 +174,11 @@ namespace Mono.Linker.Steps
 
 			using (var fs = File.Open (Path.Combine (Context.OutputDirectory, Context.PInvokesListFile), FileMode.Create)) {
 				var values = Context.PInvokes.Distinct ().OrderBy (l => l);
+				// Ignore warning, since we're just enabling analyzer for dogfooding
+#pragma warning disable IL2026
 				var jsonSerializer = new DataContractJsonSerializer (typeof (List<PInvokeInfo>));
 				jsonSerializer.WriteObject (fs, values);
+#pragma warning restore IL2026
 			}
 		}
 

src/linker/Linker/Driver.cs

@@ -832,7 +832,11 @@ namespace Mono.Linker
 				if (File.Exists (assemblyPath)) {
 					// The CLR will return the already-loaded assembly if the same path is requested multiple times
 					// (or even if a different path specifies the "same" assembly, based on the MVID).
+
+					// Ignore warning, since we're just enabling analyzer for dogfooding
+#pragma warning disable IL2026
 					return AssemblyLoadContext.Default.LoadFromAssemblyPath (assemblyPath);
+#pragma warning restore IL2026
 				}
 				Context.LogError (null, DiagnosticId.AssemblyInCustomStepOptionCouldNotBeFound, arg);
 			} else
@@ -992,7 +996,10 @@ namespace Mono.Linker
 
 		Type? ResolveStepType (string type, Assembly assembly)
 		{
+			// Ignore warning, since we're just enabling analyzer for dogfooding
+#pragma warning disable IL2026
 			Type? step = assembly != null ? assembly.GetType (type) : Type.GetType (type, false);
+#pragma warning restore IL2026
 
 			if (step == null) {
 				Context.LogError (null, DiagnosticId.CustomStepTypeCouldNotBeFound, type);
@@ -1004,7 +1011,10 @@ namespace Mono.Linker
 
 		TStep? ResolveStep<TStep> (string type, Assembly assembly) where TStep : class
 		{
+			// Ignore warning, since we're just enabling analyzer for dogfooding
+#pragma warning disable IL2026
 			Type? step = assembly != null ? assembly.GetType (type) : Type.GetType (type, false);
+#pragma warning restore IL2026
 
 			if (step == null) {
 				Context.LogError (null, DiagnosticId.CustomStepTypeCouldNotBeFound, type);

test/Mono.Linker.Tests.Cases/RequiresCapability/BasicRequires.cs

@@ -5,6 +5,8 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
+using System.IO;
+using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;
 using System.Runtime.InteropServices;
@@ -190,9 +192,13 @@ namespace Mono.Linker.Tests.Cases.RequiresCapability
 
 			class TestType { }
 
+			static T MakeNew<T> () where T : new() => new T ();
+			static T MakeNew2<T> () where T : new() => MakeNew<T> ();
+
 			public static void Test ()
 			{
 				GenericTypeWithStaticMethodViaLdftn ();
+				MakeNew2<TestType> ();
 			}
 		}
 	}