Preserve "notnull" and "allows ref struct" constraints in GenAPI#54455
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Fix GenAPI reference source generation so generic type, method, and delegate declarations preserve notnull constraints from metadata. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Pull request overview
Updates GenAPI’s C# syntax generation so notnull generic constraints are preserved when emitting declarations from metadata, addressing missing constraints that can cause downstream API-compat deltas.
Changes:
- Augments generated type/method/delegate declarations to add
where T : notnullconstraint clauses whenITypeParameterSymbol.HasNotNullConstraintis present (while suppressing emission for overrides and explicit interface implementations). - Adds/updates unit tests and baselines to validate
notnullconstraint preservation across types, methods, delegates, and synthesized struct dummy-field scenarios.
Show a summary per file
| File | Description |
|---|---|
| test/Microsoft.DotNet.GenAPI.Tests/CSharpFileBuilderTests.cs | Adds a focused notnull constraint generation test and updates struct baseline expectations to include where T : notnull. |
| src/Compatibility/GenAPI/Microsoft.DotNet.GenAPI/SyntaxGeneratorExtensions.cs | Implements post-processing to inject notnull constraint clauses into generated syntax nodes, with special-casing to avoid invalid emission on overrides/explicit impls. |
Copilot's findings
- Files reviewed: 2/2 changed files
- Comments generated: 2
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
ViktorHofer
changed the title
ViktorHofer
changed the title
Preserve generated constraint clause ordering when adding missing metadata-only constraints, and add regression coverage for explicit interface implementations. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
This was referenced May 27, 2026
MichaelSimons
approved these changes
May 27, 2026
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Fixes #54450.
Fixes #47113.
Summary
notnullgeneric constraints when GenAPI generates C# declarations from metadata.allows ref structgeneric constraints and keep them last in generated constraint lists.Testing
.\.dotnet\dotnet.exe build test\Microsoft.DotNet.GenAPI.Tests\Microsoft.DotNet.GenAPI.Tests.csproj -p:SdkTargetFramework=net10.0 --no-restore.\.dotnet\dotnet.exe exec artifacts\bin\Microsoft.DotNet.GenAPI.Tests\Debug\net10.0\Microsoft.DotNet.GenAPI.Tests.dll -method "*TestAllowsRefStructGenericConstraintGeneration*" -method "*TestNotNullGenericConstraintGeneration*" -method "*TestSynthesizePrivateFieldsForNestedGenericTypes*" -method "*TestSynthesizePrivateFieldsAngleBrackets*"