Add content for config source gen with interceptors

[IEvangelist]

Summary

• Extend config extensions doc with binding source generator info

Fixes #36939, /cc @ericstj

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Internal previews

📄 File	🔗 Preview link
docs/core/extensions/configuration-generator.md	docs/core/extensions/configuration-generator
docs/core/extensions/configuration.md	docs/core/extensions/configuration

[ericstj]

@dotnet/area-extensions-configuration @tarekgh @eiriktsarpalis cc @eerhardt @steveharter

[tarekgh]

The changes LGTM. Thanks @IEvangelist!

I have a suggestion but I'm not sure if it is worth adding. The provided sample is good, we can show a sample of the generated source too with warning the users may not get exact generated code as the source gen is evolving.

Also, using <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles> in the project will make the build process keep the generated code that allow users to inspect it.

[IEvangelist]

EmitCompilerGeneratedFiles

Hi @tarekgh - thanks for the quick review. I just tried adding the <EmitCompilerGeneratedFiles>true</EmitCompilerGeneratedFiles> but even after multiple forced clean/builds, it is not working.

Here's the error I'm seeing:

Exception details

``` 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : Unhandled Exception: System.IO.DirectoryNotFoundException: Could not find a part of the path 'C:\Users\david\source\repos\docs\docs\core\extensions\snippets\configuration\console-binder-gen\obj\Debug\net8.0\generated\Microsoft.Extensions.Configuration.Binder.SourceGeneration\Microsoft.Extensions.Configuration.Binder.SourceGeneration.ConfigurationBindingGenerator'. 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at System.IO.Directory.InternalCreateDirectory(String fullPath, String path, Object dirSecurityObj, Boolean checkHost) 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at System.IO.Directory.InternalCreateDirectoryHelper(String path, Boolean checkHost) 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at Microsoft.CodeAnalysis.CommonCompiler.CompileAndEmit(TouchedFileLogger touchedFilesLogger, Compilation& compilation, ImmutableArray`1 analyzers, ImmutableArray`1 generators, ImmutableArray`1 additionalTextFiles, AnalyzerConfigSet analyzerConfigSet, ImmutableArray`1 sourceFileAnalyzerConfigOptions, ImmutableArray`1 embeddedTexts, DiagnosticBag diagnostics, ErrorLogger errorLogger, CancellationToken cancellationToken, CancellationTokenSource& analyzerCts, AnalyzerDriver& analyzerDriver, Nullable`1& generatorTimingInfo) 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at Microsoft.CodeAnalysis.CommonCompiler.RunCore(TextWriter consoleOutput, ErrorLogger errorLogger, CancellationToken cancellationToken) 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at Microsoft.CodeAnalysis.CommonCompiler.Run(TextWriter consoleOutput, CancellationToken cancellationToken) 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at Microsoft.CodeAnalysis.CSharp.CommandLine.Csc.<>c__DisplayClass1_0.b__0(TextWriter tw) 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at Microsoft.CodeAnalysis.CommandLine.ConsoleUtil.RunWithUtf8Output[T](Func`2 func) 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at Microsoft.CodeAnalysis.CSharp.CommandLine.Csc.Run(String[] args, BuildPaths buildPaths, TextWriter textWriter, IAnalyzerAssemblyLoader analyzerLoader) 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at Microsoft.CodeAnalysis.CommandLine.BuildClient.RunLocalCompilation(String[] arguments, BuildPaths buildPaths, TextWriter textWriter) 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at Microsoft.CodeAnalysis.CommandLine.BuildClient.RunCompilation(IEnumerable`1 originalArguments, BuildPaths buildPaths, TextWriter textWriter, String pipeName) 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at Microsoft.CodeAnalysis.CommandLine.BuildClient.Run(IEnumerable`1 arguments, RequestLanguage language, CompileFunc compileFunc, CompileOnServerFunc compileOnServerFunc, ICompilerServerLogger logger) 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at Microsoft.CodeAnalysis.CSharp.CommandLine.Program.MainCore(String[] args) 1>C:\Program Files\Microsoft Visual Studio\2022\Preview\MSBuild\Current\Bin\Roslyn\Microsoft.CSharp.Core.targets(89,5): error : at Microsoft.CodeAnalysis.CSharp.CommandLine.Program.Main(String[] args) ```

[tarekgh]

I just tried adding the true but even after multiple forced clean/builds, it is not working.

EmitCompilerGeneratedFiles is documented here https://learn.microsoft.com/en-us/dotnet/csharp/roslyn-sdk/source-generators-overview and worked all the time for me. Could your machine not be enabled for long paths? https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation?tabs=registry#enable-long-paths-in-windows-10-version-1607-and-later