Add unsafe evolution migration code fixers by EgorBo · Pull Request #130611 · dotnet/runtime

EgorBo · 2026-07-13T09:23:32Z

Spec: https://github.com/dotnet/csharplang/blob/main/proposals/unsafe-evolution.md

What it does:

Adds IL5005 to remove legacy or invalid unsafe modifiers.
- Type declarations such as classes, structs, interfaces, records, record structs, and enums.
- Delegate declarations, static constructors, and destructors.
- Methods, instance constructors, operators, conversion operators, local functions, properties, indexers, and events when:
  - no pointer or function pointer in the signature (we keep those caller-unsafe)
  - no <safety> comment. It's a sign that this unsafe was from unsafe-v1.
- Keeps unsafe when required by interop, partial members, overrides, or interface contracts.
Adds IL5006 to add required unsafe blocks, expressions, and contract modifiers.
Adds unsafe and <safety> placeholders to unannotated interop declarations.
Covers partial members, interfaces, accessors, stackalloc, async code, top-level statements, and scoped refs.

How to run it from the repo root:

C:\prj\dotnet-latest\dotnet.cmd build .\src\tools\illink\src\ILLink.CodeFix\ILLink.CodeFixProvider.csproj -c Debug --no-restore

$env:EnableUnsafeMigration = 'true'

C:\prj\dotnet-latest\dotnet.cmd format analyzers .\src\libraries\System.Text.Json\src\System.Text.Json.csproj -f net11.0 --diagnostics IL5005 --severity info --no-restore
C:\prj\dotnet-latest\dotnet.cmd format analyzers .\src\libraries\System.Text.Json\src\System.Text.Json.csproj -f net11.0 --diagnostics IL5006 --severity info --no-restore
C:\prj\dotnet-latest\dotnet.cmd format analyzers .\src\libraries\System.Text.Json\src\System.Text.Json.csproj -f net11.0 --diagnostics IL5006 --severity info --no-restore

C:\prj\dotnet-latest\dotnet.cmd build .\src\libraries\System.Text.Json\src\System.Text.Json.csproj -f net11.0 -c Debug --no-restore -p:BuildProjectReferences=false -p:EnableUnsafeMigration=true

I was using the latest daily SDK in C:\prj\dotnet-latest, not sure the bootstrapped one contains all the new C# features.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: c3ccf7c6-8a32-4c31-9e31-12f0f1d2a026

Copilot

Pull request overview

This PR adds a DEBUG-only “unsafe evolution” migration analyzer + code fixers to ILLink, introducing two new IL* diagnostics (IL5005/IL5006) to (1) remove legacy/invalid unsafe modifiers and (2) migrate unsafe usages by adding explicit unsafe contexts and safety placeholders. It also wires up additional MSBuild properties and live-ILLink behavior to enable the migration experience, and adds/extends Roslyn analyzer/codefix tests.

Changes:

Add UnsafeMigrationAnalyzer + UnsafeMigrationAnalysis to detect modifier removals, required declaration updates, and unsafe-operation sites (behind #if DEBUG).
Add two new code fix providers (modifier removal + usage migration) and supporting document/AST rewrite helpers (behind #if DEBUG).
Add new diagnostic strings/IDs and update build/targets/tests to enable and validate the migration workflow.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/tools/illink/test/ILLink.RoslynAnalyzer.Tests/RequiresUnsafeCodeFixTests.cs	Adds test helpers and extensive test coverage for IL5005/IL5006 codefix behavior.
src/tools/illink/src/ILLink.Shared/SharedStrings.resx	Adds user-facing title/message strings for the new unsafe migration diagnostics.
src/tools/illink/src/ILLink.Shared/DiagnosticId.cs	Adds DEBUG-only diagnostic IDs and introduces an “Unsafe” category range mapping.
src/tools/illink/src/ILLink.Shared/DiagnosticCategory.cs	Adds DEBUG-only `Unsafe` category constant.
src/tools/illink/src/ILLink.RoslynAnalyzer/UnsafeMigrationAnalyzer.cs	New analyzer that reports file-level migration diagnostics when migration is enabled.
src/tools/illink/src/ILLink.RoslynAnalyzer/UnsafeMigrationAnalysis.cs	New analysis engine for modifier removals, contract/declaration updates, and unsafe operation locations.
src/tools/illink/src/ILLink.RoslynAnalyzer/MSBuildPropertyOptionNames.cs	Adds DEBUG-only MSBuild property names used to toggle unsafe migration behavior.
src/tools/illink/src/ILLink.RoslynAnalyzer/build/Microsoft.NET.ILLink.Analyzers.props	Exposes additional compiler-visible MSBuild properties used by the migration flow.
src/tools/illink/src/ILLink.CodeFix/UnsafeUsageMigrationCodeFixProvider.cs	New code fix provider that migrates unsafe usage sites (wrap blocks/expressions, etc.).
src/tools/illink/src/ILLink.CodeFix/UnsafeUsageDocumentFixer.cs	New document fixer implementing the migration transformations and heuristics.
src/tools/illink/src/ILLink.CodeFix/UnsafeModifierMigrationCodeFixProvider.cs	New code fix provider that removes legacy `unsafe` modifiers when eligible.
src/tools/illink/src/ILLink.CodeFix/UnsafeCodeFixHelpers.cs	New shared helpers for adding unsafe contexts and safety documentation.
src/tools/illink/src/ILLink.CodeFix/Resources.resx	Adds code fix titles for the new migration fixers.
eng/liveILLink.targets	Updates live-ILLink wiring to support enabling unsafe migration and design-time analyzer referencing.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: c3ccf7c6-8a32-4c31-9e31-12f0f1d2a026

Copilot

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated 3 comments.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: c3ccf7c6-8a32-4c31-9e31-12f0f1d2a026

Copilot

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated 3 comments.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: c3ccf7c6-8a32-4c31-9e31-12f0f1d2a026

Copilot

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated no new comments.

Copilot

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated 2 comments.

+        private static SyntaxNode AddUnsafeModifier(
+            SyntaxNode declaration,
+            SyntaxGenerator generator)
+            => declaration is AccessorDeclarationSyntax accessor
+                ? accessor
+                    .WithModifiers(accessor.Modifiers.Insert(
+                        0,
+                        SyntaxFactory.Token(SyntaxKind.UnsafeKeyword)
+                            .WithTrailingTrivia(SyntaxFactory.Space)))
+                    .WithKeyword(accessor.Keyword.WithLeadingTrivia(SyntaxFactory.TriviaList()))
+                    .WithLeadingTrivia(accessor.GetLeadingTrivia())
+                : generator.WithModifiers(
+                    declaration,
+                    generator.GetModifiers(declaration).WithIsUnsafe(true))
+                    .WithLeadingTrivia(declaration.GetLeadingTrivia());


+            if (expression.DescendantNodesAndSelf().Any(static node => node is AwaitExpressionSyntax))
+                return false;
+
+            ITypeSymbol? type = semanticModel.GetTypeInfo(expression).Type;
+            return type?.SpecialType != SpecialType.System_Void;
+        }


Add unsafe evolution migration code fixers

8b667be

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: c3ccf7c6-8a32-4c31-9e31-12f0f1d2a026

Copilot AI review requested due to automatic review settings July 13, 2026 09:23

EgorBo requested a review from sbomer as a code owner July 13, 2026 09:23

github-actions Bot added the area-Tools-ILLink .NET linker development as well as trimming analyzers label Jul 13, 2026

Copilot started reviewing on behalf of EgorBo July 13, 2026 09:24 View session

EgorBo mentioned this pull request Jul 13, 2026

ILLink: codefix for C# unsafe evolution #128304

Closed