未在配置的文件夹中发出的 C# 源生成的文件

问：

给定以下 C# 源代码生成器项目文件：

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
      <EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.7.0" />
  </ItemGroup>

</Project>

和生成器源代码：

    [Generator]
    public class HFGen1 : ISourceGenerator {
        public void Execute(GeneratorExecutionContext context)
        {
            StringBuilder sourceBuilder = new StringBuilder(@"
using System;
namespace HelloWorldGenerated
{
    public static class HelloWorld
    {
        public static void SayHello() 
        {
            Console.WriteLine(""Hello from generated code!"");
            Console.WriteLine(""The following syntax trees existed in the compilation that created this program:"");
");

            // using the context, get a list of syntax trees in the users compilation
            IEnumerable<SyntaxTree> syntaxTrees = context.Compilation.SyntaxTrees;

            // add the filepath of each tree to the class we're building
            foreach (SyntaxTree tree in syntaxTrees) {
                sourceBuilder.AppendLine($@"Console.WriteLine(@"" - {tree.FilePath}"");");
            }

            // finish creating the source to inject
            sourceBuilder.Append(@"
        }
    }
}");

            // inject the created source into the users compilation
            context.AddSource("helloWorldGenerated.g.cs", SourceText.From(sourceBuilder.ToString(), Encoding.UTF8));

        }

        public void Initialize(GeneratorInitializationContext context)
        {
        }
    }

以及生成器目标项目的以下补充：

  <ItemGroup>
    <ProjectReference Include="..\HFGen\HFGen.csproj" 
                      OutputItemType="Analyzer"
                      ReferenceOutputAssembly="false" />
  </ItemGroup>
    <PropertyGroup>
        <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles>
        <CompilerGeneratedFilesOutputPath>Generated</CompilerGeneratedFilesOutputPath>
    </PropertyGroup>    

结果是有效的，除了：

生成的文件不会在“Generated”文件夹中发出。创建“Generated”文件夹，生成的代码文件写入 Temp 文件夹（默认行为，不带 EmitCompilerGeneratedFiles）。

怎么了？