[jkoritzinsky]

Switch the existing ILAsm NuGet packages to managed ilasm, then migrate their
pack ownership to the SDK without changing the consumer package IDs or native
asset paths.

Ordered phase checkpoints

1. eb5ed0ea244: retain pkgproj packaging and replace its payload with published
   managed ilasm. Add ilasm_inbuild.csproj for host packages, following the
   crossgen2 inbuild single-file/R2R pattern.
2. 5a183c36758: move RID-specific SDK packaging into the ilasm projects,
   including published symbols. Retain the pkgproj lineup at this checkpoint.
   Include package production in the tools.ilasm subset and existing CI.
3. e72d13142f7: replace the lineup pkgproj with an SDK NoTargets package
   project, reusing the shared official RID definitions and runtime.json
   generation. Preserve identity-package leg selection and additional host
   packages.

Package-layout comparison

Retained and compared actual phase-1 pkgproj archives against phases 2 and 3:
18 archives per phase across win-x64, win-x86, win-arm64, and an ARM64 target
build producing a separate win-x64 host package. Payload/resource entry paths,
symbol paths, Windows ZIP attributes, package identity/contract metadata and PE
architectures match. The final lineup's runtime.json is byte-identical to phase
1, including all 19 default RID mappings and dependency ranges. No new framework,
ILAssembler, System.CommandLine, or build-task dependencies are exposed.

Accounted differences: generated core-property UUIDs/relationship IDs and NuGet
generator version; real SDK repository revision/branch metadata; omission of
obsolete nuspec owners and explicit false license-acceptance metadata. Rebuilt
executable/PDB bytes differ; this is a layout/contract comparison, not a claim of
bit-identical codegen. SDK symbol archives are emitted beside regular packages
instead of the legacy symbols output subdirectory.

Validation

• Clean baseline: .\dotnet.cmd msbuild src\tools\ilasm\src\ilasm\ilasm.csproj -restore -t:Publish -p:Configuration=Release -p:NuGetAudit=false — passed.
• All three phases: .\.dotnet\dotnet.exe msbuild src\coreclr\.nuget\Microsoft.NETCore.ILAsm\Microsoft.NETCore.ILAsm.proj -restore -t:Pack -p:Configuration=Release -p:NuGetAudit=false -p:TargetArchitecture=<x64|x86|arm64> -p:PackageOutputPath=<phase-specific-directory> — passed, with matching per-target restores before phase-1 packaging.
• Host packaging: the same Pack command with -p:TargetArchitecture=arm64 -p:BuildHostILTools=true — passed in all phases.
• .\build.cmd tools.ilasm -c Release -test /p:NuGetAudit=false — passed after phases 2 and 3; 5,578 tests total, 5,575 passed, 3 existing skips, no failures/errors.
• Extracted phase-1 and final x64/x86/host executables: --help and assembly of a minimal IL DLL — passed.
• Isolated local-feed consumer restore with .\.dotnet\dotnet.exe restore <Consumer.csproj> --configfile <local-feed-config> -p:RuntimeIdentifier=<win-x64|win-x86|win-arm64> — passed; each selects exactly its RID package through the lineup.
• Identity-package suppression, shared RID-list parity (default, Windows-only, custom RID), archive comparisons, and git diff --check — passed.

Validation is Windows-only, as requested. ARM64 was cross-built, not executed.
Linux/macOS/community-platform production, Unix executable modes, bootstrap
source-build packs and official signing/release legs are unverified. All legacy
advertised RIDs remain; availability of compatible packs/toolchains for every
legacy platform is not established by this PR's local validation. Publish/restore
failures are not hidden by native fallbacks or synthetic payloads.

Note

This pull request was generated with GitHub Copilot.

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[am11]

Tested on openbsd and found some gaps (even in main), fixed in #136571.

[Copilot]

🟡 Changes recommended

Unresolved regressions cause duplicate or missing ILAsm packages across build configurations and break resource-enabled builds with the replacement managed tool.

4 open issues

• Preserve ILAsm packages for Mono and Tizen builds · New
• Fix host ILAsm selection in cross-architecture builds · New
• Restore BuildIdentityPackage selection policy · New
• Add resource support to managed ilasm · New

What changed in this PR

This PR moves ILAsm NuGet packaging from legacy pkgproj infrastructure to SDK projects, using managed ilasm while retaining the existing package IDs and native asset paths.

Changes:

• Adds shared SDK packaging settings and a separate host-tool publish project.
• Replaces the legacy lineup package with a NoTargets project and runtime-graph generation task.
• Integrates package production into build subsets and ILAsm CI.

File	Description
src/​tools/​ilasm/​src/​ilasm/​ilasm.props	Shares tool settings and packages published binaries and symbols.
src/​tools/​ilasm/​src/​ilasm/​ilasm.csproj	Imports shared packaging settings.
src/​tools/​ilasm/​src/​ilasm/​ilasm_inbuild.csproj	Adds single-file host-tool publishing.
src/​tasks/​installer.tasks/​installer.tasks.csproj	References NuGet.Versioning for runtime-graph generation.
src/​tasks/​installer.tasks/​GenerateILAsmRuntimeGraph.cs	Generates RID-specific package dependency mappings.
src/​coreclr/​.nuget/​pkgproj.props	Imports the extracted shared RID definitions.
src/​coreclr/​.nuget/​package-rids.props	Centralizes official and custom package RIDs.
src/​coreclr/​.nuget/​Microsoft.NETCore.ILAsm/​Microsoft.NETCore.ILAsm.proj	Removes the legacy packaging traversal.
src/​coreclr/​.nuget/​Microsoft.NETCore.ILAsm/​Microsoft.NETCore.ILAsm.pkgproj	Removes native ILAsm pkgproj packaging.
src/​coreclr/​.nuget/​Microsoft.NETCore.ILAsm/​Microsoft.NETCore.ILAsm.Package.csproj	Adds SDK-based lineup packaging.
src/​coreclr/​.nuget/​coreclr-packages.proj	Removes the legacy ILAsm project reference.
eng/​Subsets.props	Selects managed ILAsm and packaging projects.
eng/​pipelines/​coreclr/​ilasm.yml	Adds packaging triggers and enables CI packing.

_{Review effort: Balanced}