[release/8.0] Remove package baseline infrastructure

[Copilot]

Backport of #64337 to release/8.0 - removes unused package baseline validation and generation tooling.

Description

Package baseline infrastructure was designed to prevent dependency version regressions in servicing builds. The code path is no longer executed, making it dead code.

Removed:

• eng/Baseline.Designer.props (8.0.21 version definitions)
• eng/Baseline.xml (baseline configuration)
• eng/tools/BaselineGenerator/ (generation tool)

Updated:

• Directory.Build.targets - removed baseline import and BaselinePackageVersion logic
• eng/targets/ResolveReferences.targets - removed BaselinePackageReference resolution and validation
• eng/targets/Packaging.targets - removed EnsureBaselineIsUpdated target
• AspNetCore.sln - removed BaselineGenerator project references
• eng/scripts/CodeCheck.ps1 - removed baseline regeneration step
• src/Components/Components/src/*.csproj - removed SuppressBaselineReference items
• Documentation updates (PreparingPatchUpdates.md, ReferenceResolution.md, UpdatingMajorVersionAndTFM.md)

Customer Impact

None. Internal build infrastructure cleanup only.

Regression?

• Yes
• No

Risk

• High
• Medium
• Low

Removing dead code that never executes. Validated with successful C# project builds (Http.Abstractions, Components).

Verification

• Manual (required)
• Automated

Packaging changes reviewed?

• Yes
• No
• N/A

Baseline validation/generation is removed from build process.

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When servicing release/2.1

• Make necessary changes in eng/PatchConfig.props

Original prompt

Backport the changes from PR #64337 ([release/10.0] Get rid of package baseline) in dotnet/aspnetcore to the release/8.0 branch.

Context:

• Original PR: [release/10.0] Get rid of package baseline #64337
• Intent: Remove the package baseline in release/8.0 in the same manner as was done for release/10.0.

Requirements:

• Cherry-pick or reapply the commits from PR [release/10.0] Get rid of package baseline #64337 onto release/8.0, resolving any conflicts appropriately for the 8.0 codebase.
• Ensure any version-specific paths, package names, or baseline configurations that differ in 8.0 are handled correctly.
• Build and run tests to verify there are no regressions.
• Update any documentation or configs if the package baseline removal affects them.
• Prepare a PR targeting release/8.0 with a clear description including links to the original PR and a summary of changes.

PR description should include:

• "Backport of [release/10.0] Get rid of package baseline #64337 to release/8.0"
• Notes on any differences from the 10.0 change, if applicable.
• Validation steps performed.

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[Copilot]

Pull request overview

This PR backports changes from release/10.0 (#64337) to remove the unused package baseline validation and generation infrastructure from release/8.0. The baseline infrastructure was originally designed to prevent dependency version regressions in servicing builds but is no longer executed, making it dead code.

Changes:

• Removed baseline configuration files (Baseline.xml, Baseline.Designer.props) and the BaselineGenerator tool
• Cleaned up MSBuild targets to remove baseline validation, reference resolution, and version logic
• Updated project files and scripts to remove baseline references and generation steps
• Updated documentation to remove instructions for baseline maintenance

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
eng/Baseline.xml	Deleted baseline configuration with version 8.0.21 package definitions
eng/Baseline.Designer.props	Deleted generated MSBuild properties file (998 lines) with baseline package versions and references
eng/tools/BaselineGenerator/.	Deleted complete baseline generation tool (README, Program.cs, .csproj)
eng/targets/ResolveReferences.targets	Removed BaselinePackageReference resolution logic and validation warnings/errors
eng/targets/Packaging.targets	Removed EnsureBaselineIsUpdated validation target
Directory.Build.targets	Removed Baseline.Designer.props import and BaselinePackageVersion-based versioning logic
eng/scripts/CodeCheck.ps1	Removed baseline regeneration step from code check script
eng/Versions.props	Removed ValidateBaseline property
eng/Dependencies.props	Removed comment references to BaselinePackageReference
AspNetCore.sln	Removed BaselineGenerator project and configuration
eng/tools/tools.slnf	Removed BaselineGenerator project reference
src/Components/Components/src/Microsoft.AspNetCore.Components.csproj	Removed SuppressBaselineReference item group with comments
docs/PreparingPatchUpdates.md	Removed instructions to update package baselines
docs/ReferenceResolution.md	Removed baseline-related documentation and examples
docs/UpdatingMajorVersionAndTFM.md	Removed baseline update instructions