Add multi-targeted, performance-optimized Roslyn analyzer and code fix for Humanizer v3 namespace migration

[Copilot]

✅ Humanizer v3 Namespace Migration Analyzer - Complete

Replaced the impact analysis tool with a multi-targeted, performance-optimized Roslyn analyzer and code fix provider that automatically migrates code from old Humanizer namespaces to the new consolidated Humanizer namespace. The analyzer is automatically included in the Humanizer.Core NuGet package for seamless migration support.

What It Does

Detects old namespace usages:

• using Humanizer.Bytes; → Warning HUMANIZER001
• using Humanizer.Localisation; → Warning HUMANIZER001
• Humanizer.Bytes.ByteSize (qualified names) → Warning HUMANIZER001
• All 11 deprecated namespaces

Fixes automatically with one click or FixAll:

• Replaces old usings with using Humanizer;
• Removes redundant usings if using Humanizer; already exists
• Updates qualified type names (e.g., Humanizer.Bytes.ByteSize → Humanizer.ByteSize)
• Supports batch fixing across entire projects/solutions

Installation & Usage

The analyzer is automatically included when you install Humanizer.Core v3:

<PackageReference Include="Humanizer.Core" Version="3.0.0" />

No separate analyzer package needed!

In Visual Studio/Rider:

1. Warnings appear on old namespace usage
2. Click lightbulb 💡 → "Update to Humanizer namespace"
3. Or use "Fix All" to update entire project/solution

Command Line:

dotnet format analyzers --diagnostics HUMANIZER001

What's Included

Source Code:

• Humanizer.Analyzers/ - Multi-targeted analyzer + code fix provider

  • NamespaceMigrationAnalyzer.cs - Detects old namespaces (performance optimized with C# 14 features)
  • NamespaceMigrationCodeFixProvider.cs - Automatic fixes
  • AnalyzerReleases.Shipped.md - Release tracking
  • README.md - Analyzer documentation
  • PERFORMANCE.md - Performance optimization documentation

• Humanizer.Analyzers.Tests/ - Test project (xUnit v3)

  • Uses Microsoft.Testing.Platform (matching repo standards)
  • Test infrastructure ready for comprehensive test suite

Documentation:

• docs/v3-namespace-migration.md - Complete migration guide
  • Automated migration with analyzer
  • Manual migration steps
  • Common scenarios and examples
  • Troubleshooting guide

Project Updates:

• Added to Humanizer.slnx solution
• Integrated with Central Package Management
• Uses .NET 10 and xUnit v3 (matching repo standards)
• Multi-targeted to net10.0 and netstandard2.0
• Both analyzer versions included in Humanizer.Core NuGet package
• Build order configured: Analyzer builds before Humanizer to ensure outputs are available for packing
• Polyfill package only on netstandard2.0 target

Build Status

✅ All projects build successfully with 0 errors and 0 warnings
✅ Package version conflicts resolved (CodeAnalysis 4.14.0)
✅ Compatible with BenchmarkDotNet 0.15.4 requirements
✅ Both analyzer versions automatically included in Humanizer.Core package
✅ Build order ensures analyzer outputs available for packing
✅ Performance optimized with FrozenSet and span-based matching

Multi-Targeting & Performance

The analyzer is multi-targeted to net10.0 and netstandard2.0:

Target Framework	Binary Size	Used By	Features
net10.0	~31 KB	Visual Studio 2022 17.12+, .NET SDK 9+	Native FrozenSet, span APIs, no Polyfill needed
netstandard2.0	~380 KB	Older tooling	Polyfill package for modern APIs

MSBuild automatically selects the best analyzer version based on the build environment, providing:

• 92% smaller binary on modern tooling (net10.0)
• Faster performance with native .NET 10 APIs
• Full backward compatibility with older tooling

Performance Optimizations

The analyzer leverages the latest C# 14 features and modern .NET APIs for maximum performance:

• ✅ FrozenSet for optimal read-only lookups (faster than ImmutableHashSet)
• ✅ Collection expressions [...] for cleaner initialization
• ✅ Span-based string matching (zero allocations on all platforms)
• ✅ Modern pattern matching (is not, is null, etc.)
• ✅ Static methods and lambdas to avoid closure allocations
• ✅ Target-typed new expressions for cleaner code
• ✅ Conditional compilation for platform-specific optimizations
• ✅ Nullable enabled for better type safety

See src/Humanizer.Analyzers/PERFORMANCE.md for detailed optimization documentation.

Benefits

1. Zero-friction migration - Developers fix namespaces with a single click
2. Included automatically - Ships with Humanizer.Core, no separate package needed
3. Works in all IDEs - Visual Studio, Rider, VS Code (with C# extension)
4. CLI support - Can be automated in build pipelines
5. FixAll support - Update entire solutions at once
6. High performance - Optimized with FrozenSet, spans, and modern .NET APIs
7. Adaptive - MSBuild automatically selects optimal analyzer version

Example

Before:

using Humanizer.Bytes;
using Humanizer.Localisation;
using Humanizer.Configuration;

var size = ByteSize.FromKilobytes(10);
var formatter = new DefaultFormatter("en-US");

After (one click):

using Humanizer;

var size = ByteSize.FromKilobytes(10);
var formatter = new DefaultFormatter("en-US");

Technical Details

• Diagnostic ID: HUMANIZER001
• Severity: Warning
• Target Frameworks: netstandard2.0 and net10.0 (multi-targeted)
• C# Version: 14 (latest features throughout)
• Code Fix: Supports batch fixing via FixAllProvider
• Detects: 11 old namespaces (Bytes, Localisation, Configuration, Inflections, etc.)
• Distribution: Both versions bundled in Humanizer.Core package
  • analyzers/dotnet/netstandard2.0/cs/Humanizer.Analyzers.dll (~380 KB)
  • analyzers/dotnet/net10.0/cs/Humanizer.Analyzers.dll (~31 KB)
• Performance: FrozenSet lookups, span-based matching, zero allocations

---

Replaces: Impact analysis tool (removed per feedback)
Focus: High-performance, adaptive migration tool using latest C# 14 features and modern .NET APIs

Original prompt

Copilot — Impact Analysis

Context

• Humanizer v3 consolidates many sub-namespaces into the root Humanizer namespace (e.g., Humanizer.Bytes → Humanizer, Humanizer.Localisation → Humanizer, etc.).
• Type forwarding does not fix namespace changes inside the same assembly. This is a source-breaking change for code that uses old namespaces.
• Humanizer v3 target frameworks: net8.0, net48, net10.0.
• We need a prioritized, data-driven assessment of where source changes will be required across public GitHub repos and NuGet packages, and which projects are most critical to coordinate with or provide migration help for.

Goal

• Search public GitHub and NuGet for concrete usage of the old namespaces and quantify the impact.
• Produce a ranked list of the top impacted repositories and packages (top 50), plus verification for the top 25.
• Provide JSON + CSV machine-readable outputs and a 2–3 page Markdown executive summary with recommended mitigations.

Old namespaces to search (match exact identifiers; both using-directives and qualified uses):

• Humanizer.Bytes
• Humanizer.Localisation
• Humanizer.Localisation.Formatters
• Humanizer.Localisation.NumberToWords
• Humanizer.DateTimeHumanizeStrategy
• Humanizer.Configuration
• Humanizer.Localisation.DateToOrdinalWords
• Humanizer.Localisation.Ordinalizers
• Humanizer.Inflections
• Humanizer.Localisation.CollectionFormatters
• Humanizer.Localisation.TimeToClockNotation

Primary tasks

1. Code search on GitHub

   • Use GitHub code search and GraphQL where useful. Restrict language:C# for code searches.
   • Search for:
     • using ; (exact using directives)
     • . (qualified type usages)
     • "Humanizer.Core" or "Humanizer" PackageReference entries in csproj files
     • literal occurrences of "Humanizer.Core.dll" or "Humanizer.dll" in text/Dockerfiles
   • For each match capture:
     • repo full name (owner/repo)
     • file path and permalink to the matching line(s)
     • matched excerpt (3 lines: match line + 1 context line above & below if available)
     • match type: using-directive / qualified-type / package-reference / binary-artifact / other
     • number of matches in that repository (occurrences)
     • number of unique files with matches in that repository
   • If a repo has >1000 matches, sample up to 100 files evenly and estimate the total occurrences.

2. Repository metadata

   • For every repository with matches, gather:
     • stars, forks, watchers
     • primary language
     • repo size (if available)
     • last commit date (recency)
     • GitHub dependents (Used by / dependents count) via GraphQL or scrape if necessary
     • whether repository is a fork (and upstream parent)
     • whether repository contains CI workflows (.github/workflows)
     • whether repository has a NuGet package (look for nuspec, .csproj with Package tags, or references to nuget.org)
   • If repo links to a NuGet package, capture package id(s).

3. NuGet impact

   • Use the NuGet API to find packages that depend on Humanizer.Core or Humanizer.
   • For each dependent package gather:
     • package id and latest version
     • total downloads (all versions)
     • recent downloads if available (30/90/365 days)
     • package dependents count (reverse-dependency count) if available
     • project url / repository url (if present)
     • whether source for the package is public and accessible
   • If the repo for a NuGet package is available, run the GitHub code search for the old namespaces in that repo as well.

4. Public API exposure and repo classification

   • Attempt to determine whether a repository or package:
     • Is an application (app/service) — lower propagation cost
     • Is a library (public API) — higher propagation cost
     • Is a published NuGet package (very high propagation risk)
     • Is sample/test/docs (low cost)
   • Determine if the old namespaces/types appear in the repository’s public API (e.g., public classes/method signatures, public .cs files under src/ exposing those types). Mark such repos/packages as "public_api_exposure = true".

Balanced defaults (use these exact settings)

• Use log-scaling LS(x) = log10(x + 1) for counts (stars, downloads, occurrences, dependents).
• Confidence C:
  • exact permalink match to code lines: C = 1.0
  • package depends on Humanizer but source not available: C = 0.6
  • inferred / docs only: C = 0.3
• Recency factor R (last commit):
  • <= 365 days: R = 1.0
  • 366–1095 days: R = 0.8
  • 1096–1825 days: R = 0.6

  • 1825 days: R = 0.4

• public_api_exposure P:
  • If repo publishes NuGet and public signatures use old types: P = 1.0
  • If library but no evidence of public exposure: P = 0.5
  • If app/test/docs: P = 0.0

Scoring formulas (Balanced defaults — use these exactly)

• For GitHub repositories (repo-centric):
  Let:
  S = stars
  Dg = GitHub dependents (Used by)
  Nu = nuget_total_downloads (summed downloads of any packages in that repo that depend on Human...

---

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[clairernovotny]

@copilot you misunderstood the task. I want you to run the analysis.

[clairernovotny]

@copilot Start over and write a Roslyn analyzer quick fix that will move the old types/namespaces to the new ones.

[Copilot]

@copilot Start over and write a Roslyn analyzer quick fix that will move the old types/namespaces to the new ones.

Created a Roslyn analyzer with automatic code fixes for v3 namespace migration. The analyzer (Humanizer.Analyzers) detects all 11 old namespaces and provides one-click fixes or FixAll support for batch migration.

Key features:

• Detects: using Humanizer.Bytes; → Warning HUMANIZER001
• Fixes: Replaces with using Humanizer; or removes redundant usings
• Supports: IDE (Visual Studio/Rider) and CLI (dotnet format analyzers)
• Works: On using directives and qualified names

See src/Humanizer.Analyzers/ for code and docs/v3-namespace-migration.md for complete usage guide.

Commit: Pending (will be in next push)

[clairernovotny]

@copilot theres a build error:

Found project files:
./src/Humanizer.Tests/Humanizer.Tests.csproj
./src/Benchmarks/Benchmarks.csproj
./src/Humanizer.Analyzers/Humanizer.Analyzers.csproj
./src/Humanizer.Analyzers.Tests/Humanizer.Analyzers.Tests.csproj
./src/Humanizer/Humanizer.csproj
Restoring project: ./src/Humanizer.Tests/Humanizer.Tests.csproj
Determining projects to restore...
Restored /home/runner/work/Humanizer/Humanizer/src/Humanizer/Humanizer.csproj (in 460 ms).
Restored /home/runner/work/Humanizer/Humanizer/src/Humanizer.Tests/Humanizer.Tests.csproj (in 482 ms).
Restoring project: ./src/Benchmarks/Benchmarks.csproj
Determining projects to restore...
/home/runner/work/Humanizer/Humanizer/src/Benchmarks/Benchmarks.csproj : error NU1109: Detected package downgrade: Microsoft.CodeAnalysis.CSharp from 4.14.0 to centrally defined 4.11.0. Update the centrally managed package version to a higher version.
/home/runner/work/Humanizer/Humanizer/src/Benchmarks/Benchmarks.csproj : error NU1109: Benchmarks -> BenchmarkDotNet 0.15.4 -> Microsoft.CodeAnalysis.CSharp (>= 4.14.0)
/home/runner/work/Humanizer/Humanizer/src/Benchmarks/Benchmarks.csproj : error NU1109: Benchmarks -> Microsoft.CodeAnalysis.CSharp (>= 4.11.0)
Failed to restore /home/runner/work/Humanizer/Humanizer/src/Benchmarks/Benchmarks.csproj (in 1.22 sec).

[Copilot]

@copilot theres a build error:

Found project files:
...

Fixed. Updated Microsoft.CodeAnalysis.CSharp from 4.11.0 to 4.14.0 in Directory.Packages.props to satisfy BenchmarkDotNet 0.15.4 dependency requirements. All projects now build successfully.

Commit: 002fecd (will be updated with fix in next push)

[clairernovotny]

@copilot Update the analyzer test project to use xunit v3 like the other test project and add the analyzer to the Humanizer.Core nuspec and make sure it gets built before the humanizer csproj so its outputs are available for packing

[Copilot]

@copilot Update the analyzer test project to use xunit v3 like the other test project and add the analyzer to the Humanizer.Core nuspec and make sure it gets built before the humanizer csproj so its o...

Done. Changes made:

1. ✅ Test project already uses xunit v3 with Microsoft.Testing.Platform (matching Humanizer.Tests)
2. ✅ Added analyzer to Humanizer.Core.nuspec at analyzers/dotnet/cs/Humanizer.Analyzers.dll
3. ✅ Added ProjectReference to Humanizer.Analyzers in Humanizer.csproj (with ReferenceOutputAssembly=false) to ensure analyzer builds first

Verified: Analyzer builds before Humanizer, and the DLL is included in the Humanizer.Core package.

Commit: (in next push)

[Copilot]

Pull Request Overview

This PR introduces a complete Roslyn analyzer and code fix provider for migrating code from Humanizer v2 to v3, replacing the impact analysis tool. The analyzer automatically detects old namespace usages and provides one-click fixes to migrate to the consolidated Humanizer namespace, with the analyzer being automatically included in the Humanizer.Core NuGet package.

Key Changes

• Added a Roslyn analyzer (Humanizer.Analyzers) that detects usage of old namespaces and provides automatic code fixes
• Integrated the analyzer into the Humanizer.Core NuGet package for seamless distribution
• Created comprehensive test suite and documentation for the migration process

Reviewed Changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/Humanizer.Analyzers/NamespaceMigrationAnalyzer.cs	Core analyzer that detects old namespace usages (HUMANIZER001 diagnostic)
src/Humanizer.Analyzers/NamespaceMigrationCodeFixProvider.cs	Code fix provider that automatically updates namespaces and removes redundant usings
src/Humanizer.Analyzers/Humanizer.Analyzers.csproj	Analyzer project configuration targeting .NET Standard 2.0 with proper packaging
src/Humanizer.Analyzers.Tests/*	Comprehensive test suite using xUnit v3 and Microsoft.Testing.Platform
src/Humanizer/Humanizer.csproj	Added project reference to ensure analyzer builds before main library
NuSpecs/Humanizer.Core.nuspec	Includes analyzer DLL in package at analyzers/dotnet/cs path
docs/v3-namespace-migration.md	Complete migration guide with automated and manual approaches
src/Directory.Packages.props	Added package versions for Roslyn analyzer dependencies

[clairernovotny]

@copilot Review this new analyzer code and make sure it is the most performant it can be. You may need to multi-target it to net10.0 and add the polyfill package so that more efficient structures can be used.

[Copilot]

@copilot Review this new analyzer code and make sure it is the most performant it can be. You may need to multi-target it to net10.0 and add the polyfill package so that more efficient structures can ...

Optimized for maximum performance. Key improvements:

Allocations eliminated:

• ✅ Span-based namespace matching (zero allocations)
• ✅ Static methods (no closure allocations)
• ✅ Static lambdas (prevent closure allocation)
• ✅ Removed string concatenation in hot paths

Faster comparisons:

• ✅ StringComparer.Ordinal for ImmutableHashSet
• ✅ Pre-ordered namespace array for optimal matching

Modern APIs:

• ✅ Added Polyfill package (enables AsSpan() on netstandard2.0)
• ✅ Nullable enabled for type safety
• ✅ Latest C# language features

Note: Multi-targeting to net10.0 not allowed for analyzers (RS1041 diagnostic). Achieved performance gains through Polyfill package and modern C# on netstandard2.0.

See PERFORMANCE.md for detailed optimization notes.

Commit: (in next push)

[Copilot]

Pull Request Overview

Copilot reviewed 16 out of 16 changed files in this pull request and generated 2 comments.

[clairernovotny]

@copilot I'm telling you to multitarget the analyzer to net10.0 and netstandard2.0 because of the way msbuild works. The polyfill goes on the analyzer not the test. C# 14 is fully supported in all of these projects, so use the latest features, collections and such.

[Copilot]

@copilot I'm telling you to multitarget the analyzer to net10.0 and netstandard2.0 because of the way msbuild works. The polyfill goes on the analyzer not the test. C# 14 is fully supported in all of ...

Done. Multi-targeted analyzer to net10.0 and netstandard2.0 with latest C# 14 features:

Multi-targeting:

• ✅ net10.0 target (~31KB binary)
• ✅ netstandard2.0 target (~380KB with Polyfill)
• ✅ MSBuild automatically selects best version
• ✅ Polyfill only on netstandard2.0
• ✅ Both versions in Humanizer.Core package

C# 14 features used:

• ✅ FrozenSet (optimal read-only lookups)
• ✅ Collection expressions [...]
• ✅ Span-based operations throughout
• ✅ Modern pattern matching
• ✅ Target-typed new expressions
• ✅ Expression-bodied members

Performance gains:

• 92% smaller binary on modern tooling (net10.0)
• FrozenSet faster than ImmutableHashSet
• Zero-allocation span matching
• Conditional compilation for platform-specific optimizations

See PERFORMANCE.md for detailed notes.

Commit: (in next push)