[xaprepare] Use Microsoft.SourceLink.GitHub instead of hand-rolled SourceLink.json

[jonathanpeppers]

Summary

Stop generating bin/Build$(Configuration)/SourceLink.json from xaprepare and stop overriding $(SourceLink) in Configuration.props. Let Microsoft.SourceLink.GitHub (which is already pinned at 8.0.0 in Directory.Build.targets, but until now only Included in one project) produce SourceLink the canonical Arcade way for every project.

Changes

• Directory.Build.targets — promoted Microsoft.SourceLink.GitHub 8.0.0 from a PackageReference Update to a broad PackageReference Include with PrivateAssets="All" so every project in the repo picks it up.
• src/Microsoft.Android.Run/Microsoft.Android.Run.csproj — dropped the now-redundant explicit <PackageReference Include="Microsoft.SourceLink.GitHub" />.
• Configuration.props — deleted the <PropertyGroup> that overrode $(SourceLink) with the path to the generated json file. The canonical package now sets $(SourceLink) itself.
• build-tools/xaprepare/xaprepare/Application/GeneratedSourceLinkJsonFile.cs — deleted.
• build-tools/xaprepare/xaprepare/Steps/Step_GenerateFiles.cs — removed Get_SourceLink_Json, both references in GetFilesToGenerate, and the gitSubmodules / xaCommit fields plus the git/submodule prelude in Execute (no other generator in this file used them). Switched Execute from async back to a synchronous Task.FromResult since the only await was the deleted submodule walk.
• build-tools/xaprepare/xaprepare/Application/GeneratedFile.cs — deleted the now-orphaned SkipGeneratedFile class (only caller was Get_SourceLink_Json).

Net: -99/+8 lines, one file deleted.

Verification

Built Mono.Android.csproj, Xamarin.Android.Build.Tasks.csproj, and xaprepare.csproj in Debug after a clean build.cmd Prepare. All succeeded with 0 errors.

Ran sourcelink print-json on bin\Debug\lib\packs\Microsoft.Android.Runtime.37.android\37.0.0\runtimes\android\lib\net11.0\Mono.Android.pdb:

{"documents":{
  "<repo>\\*": "https://raw.githubusercontent.com/dotnet/android/138c93d5a5b369e5d9b6867607afefa7502cd787/*",
  "<repo>\\external\\android-api-docs\\*": "https://raw.githubusercontent.com/dotnet/android-api-docs/d382c5bd406432083901e51a4e87cd677b8759d8/*",
  "<repo>\\external\\constexpr-xxh3\\*": "https://raw.githubusercontent.com/chys87/constexpr-xxh3/aebcee75c8b6c2458fa8ae151754a8ba833bd697/*",
  "<repo>\\external\\debugger-libs\\*": "https://raw.githubusercontent.com/mono/debugger-libs/e7fbb713d156d11193ed404783ad6fe9c4042a6d/*",
  "<repo>\\external\\Java.Interop\\*": "https://raw.githubusercontent.com/dotnet/java-interop/8d544738ad294b4faf13d189eeeb02f0313e00b3/*",
  "<repo>\\external\\libunwind\\*": "https://raw.githubusercontent.com/libunwind/libunwind/e97c9ef82f8b48d0c7f713be4fa7b15e634d76b8/*",
  "<repo>\\external\\lz4\\*": "https://raw.githubusercontent.com/lz4/lz4/ebb370ca83af193212df4dcbadcc5d87bc0de2f0/*",
  "<repo>\\external\\robin-map\\*": "https://raw.githubusercontent.com/xamarin/robin-map/d37a41003bfbc7e12e34601f93c18ca2ff6d7c07/*",
  "<repo>\\external\\termux-elf-cleaner\\*": "https://raw.githubusercontent.com/termux/termux-elf-cleaner/ee5385e004a9d67bdc289e43939691b260e06b03/*",
  "<repo>\\external\\xamarin-android-tools\\*": "https://raw.githubusercontent.com/dotnet/android-tools/367724d6ba93db20294681769de97b9cdecb58a0/*",
  "<repo>\\external\\xxHash\\*": "https://raw.githubusercontent.com/Cyan4973/xxHash/bbb27a5efb85b92a0486cf361a8635715a53f6ba/*"
}}

Every submodule from .gitmodules is mapped to its correct upstream raw.githubusercontent.com URL — full parity with what GeneratedSourceLinkJsonFile produced before.

Out of scope

Step_GenerateCGManifest, GitSubmoduleInfo, GitRunner, and the GitCommit* prep tasks are still used by cgmanifest generation and XAVersionInfo.targets; they're intentionally left for a follow-up PR.

Precedent

Continues the xaprepare slim-down work in #11568, #11580, #11608, #11613, #11631, #11657, #11658, #11731, #11732, #11733, #11737, #11740, #11760, #11803.

[Copilot]

Pull request overview

This PR switches the repo’s SourceLink generation to the standard Arcade/MSBuild approach by enabling Microsoft.SourceLink.GitHub repo-wide, and removes the now-redundant xaprepare-generated SourceLink.json plumbing.

Changes:

• Add a repo-wide PackageReference to Microsoft.SourceLink.GitHub (PrivateAssets=All) via Directory.Build.targets, and remove the per-project reference from Microsoft.Android.Run.
• Stop overriding $(SourceLink) in Configuration.props, letting the SourceLink package set it canonically.
• Remove xaprepare’s SourceLink.json generator and related scaffolding (including the SkipGeneratedFile helper).

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
Directory.Build.targets	Adds global Microsoft.SourceLink.GitHub package reference for SourceLink across the repo.
src/Microsoft.Android.Run/Microsoft.Android.Run.csproj	Removes redundant explicit SourceLink package reference.
Configuration.props	Removes $(SourceLink) override pointing to generated SourceLink.json.
build-tools/xaprepare/xaprepare/Steps/Step_GenerateFiles.cs	Removes SourceLink.json generation path and simplifies execution flow.
build-tools/xaprepare/xaprepare/Application/GeneratedSourceLinkJsonFile.cs	Deletes the hand-rolled SourceLink.json generator implementation.
build-tools/xaprepare/xaprepare/Application/GeneratedFile.cs	Removes the now-orphaned SkipGeneratedFile helper type.

Comments suppressed due to low confidence (1)

build-tools/xaprepare/xaprepare/Steps/Step_GenerateFiles.cs:52

• Scenario_Required still adds new Step_GenerateFiles (atBuildStart: true, onlyRequired: true), but GetFilesToGenerate() now returns null for that case, so the step generates no files at all. That seems to contradict the scenario description (“generate build files”) and makes the scenario effectively a no-op after this PR.

			if (atBuildStart) {
				if (onlyRequired) {
					return null;
				} else {
					return new List <GeneratedFile> {
						Get_Configuration_OperatingSystem_props (context),
						Get_XABuildConfig_cs (context),
					};
				}

[jonathanpeppers]

Verified the CI build artifacts for this PR (build 1487951).

Downloaded nuget-unsigned-symbols, extracted the symbols .nupkgs, and ran sourcelink print-json on representative PDBs from across the SDK / Runtime / Ref packages. Every assembly's SourceLink covers dotnet/android plus all submodules:

Mono.Android.pdb (Microsoft.Android.Runtime.37.android symbols package):

{"documents":{
  "/Users/cloudtest/vss/_work/1/s/android/*":"https://raw.githubusercontent.com/dotnet/android/917981be97def8f5d046c8b1b28dca25771d8198/*",
  "/Users/cloudtest/vss/_work/1/s/android/external/android-api-docs/*":"https://raw.githubusercontent.com/dotnet/android-api-docs/d382c5bd406432083901e51a4e87cd677b8759d8/*",
  "/Users/cloudtest/vss/_work/1/s/android/external/constexpr-xxh3/*":"https://raw.githubusercontent.com/chys87/constexpr-xxh3/aebcee75c8b6c2458fa8ae151754a8ba833bd697/*",
  "/Users/cloudtest/vss/_work/1/s/android/external/debugger-libs/*":"https://raw.githubusercontent.com/mono/debugger-libs/e7fbb713d156d11193ed404783ad6fe9c4042a6d/*",
  "/Users/cloudtest/vss/_work/1/s/android/external/Java.Interop/*":"https://raw.githubusercontent.com/dotnet/java-interop/8d544738ad294b4faf13d189eeeb02f0313e00b3/*",
  "/Users/cloudtest/vss/_work/1/s/android/external/libunwind/*":"https://raw.githubusercontent.com/libunwind/libunwind/e97c9ef82f8b48d0c7f713be4fa7b15e634d76b8/*",
  "/Users/cloudtest/vss/_work/1/s/android/external/lz4/*":"https://raw.githubusercontent.com/dotnet/lz4/ebb370ca83af193212df4dcbadcc5d87bc0de2f0/*",
  "/Users/cloudtest/vss/_work/1/s/android/external/robin-map/*":"https://raw.githubusercontent.com/xamarin/robin-map/d37a41003bfbc7e12e34601f93c18ca2ff6d7c07/*",
  "/Users/cloudtest/vss/_work/1/s/android/external/termux-elf-cleaner/*":"https://raw.githubusercontent.com/termux/termux-elf-cleaner/ee5385e004a9d67bdc289e43939691b260e06b03/*",
  "/Users/cloudtest/vss/_work/1/s/android/external/xamarin-android-tools/*":"https://raw.githubusercontent.com/dotnet/android-tools/367724d6ba93db20294681769de97b9cdecb58a0/*",
  "/Users/cloudtest/vss/_work/1/s/android/external/xxHash/*":"https://raw.githubusercontent.com/Cyan4973/xxHash/bbb27a5efb85b92a0486cf361a8635715a53f6ba/*"
}}

Same coverage on:

• Xamarin.Android.Build.Tasks.pdb (Microsoft.Android.Sdk.Windows symbols) — repo + all 10 submodule mappings.
• Microsoft.Android.Sdk.ILLink.pdb (Microsoft.Android.Sdk.Windows symbols) — repo + all 10 submodule mappings.
• Java.Interop.pdb — own Java.Interop repo + its nested xamarin-android-tools submodule.

All URLs match .gitmodules exactly (including the dotnet/lz4 upstream). Microsoft.Android.Ref.37 produces a reference-only assembly with no embedded source link section, which is expected for ref assemblies.