Tighten NodeLaunchData.EnvironmentOverrides nullability to IDictionary<string, string?>?#13815
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OvesN merged 3 commits intoJun 4, 2026
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…y<string, string?>? Agent-Logs-Url: https://github.com/dotnet/msbuild/sessions/2e8dcdf9-a529-41ff-87b3-72b3b671a758 Co-authored-by: OvesN <150850103+OvesN@users.noreply.github.com>
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[WIP] Fix nullability mismatch in NodeLaunchData.EnvironmentOverrides
Tighten NodeLaunchData.EnvironmentOverrides nullability to IDictionary<string, string?>?
May 19, 2026
AlesProkop
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Jun 1, 2026
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Pull request overview
This PR tightens the nullability contract for node-launch environment overrides so that null values can be represented explicitly as “remove this environment variable” sentinels (used to clear DOTNET_ROOT_* variants during apphost bootstrap), eliminating previous null-forgiveness and #nullable disable workarounds.
Changes:
- Retypes
NodeLaunchData.EnvironmentOverrides(and related plumbing) toIDictionary<string, string?>?to encode null-as-sentinel semantics in the type system. - Updates
DotnetHostEnvironmentHelper.ApplyEnvironmentOverridesto accept nullable values and removes a straynull!. - Removes the
!suppression and workaround comment fromMSBuildClient, and adjusts a#nullable disablecall site viavar.
Reviewed changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| src/Framework/DotnetHostEnvironmentHelper.cs | Accept nullable override values and apply null-as-remove semantics; remove null!. |
| src/Build/BackEnd/Components/Communications/NodeProviderOutOfProcTaskHost.cs | Uses var to preserve nullable element type flow in a #nullable disable context. |
| src/Build/BackEnd/Components/Communications/NodeLauncher.cs | Retypes environment override parameter for env-block construction (Windows). |
| src/Build/BackEnd/Components/Communications/INodeLauncher.cs | Updates NodeLaunchData.EnvironmentOverrides to IDictionary<string, string?>?. |
| src/Build/BackEnd/Components/Communications/DetouredNodeLauncher.cs | Retypes override parameter for BuildXL detoured launch environment creation. |
| src/Build/BackEnd/Client/MSBuildClient.cs | Drops null-forgiveness and related workaround comment when setting overrides. |
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
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Fixes #13761
Context
DotnetHostEnvironmentHelper.CreateDotnetRootEnvironmentOverrides()returnsIDictionary<string, string?>?where null values are intentional sentinels meaning "remove this variable from the child environment" (consumed byApplyEnvironmentOverrides→environment.Remove(key)to clearDOTNET_ROOT_*arch-specific variants). ButNodeLaunchData.EnvironmentOverrideswas typedIDictionary<string, string>?, forcing both call sites to paper over the mismatch —MSBuildClient.cswith!,NodeProviderOutOfProc.csvia#nullable disable.Changes Made
INodeLauncher.cs:EnvironmentOverrides→IDictionary<string, string?>?.DotnetHostEnvironmentHelper.cs:ApplyEnvironmentOverridesoverrides param and foreach KVP retyped; drop straynull!(target dict is alreadyDictionary<string, string?>).MSBuildClient.cs: drop!and the#13761workaround comment.NodeLauncher.BuildEnvironmentBlock,DetouredNodeLauncher.CreateEnvironmentVariables: param retyped. Files are#nullable disable, so the signature is wrapped in a narrow#nullable enable annotations/#nullable disable annotationsblock rather than flipping the whole file.NodeProviderOutOfProcTaskHost.cs: local switched tovarto flow the nullable element type through without touching the file's#nullable disablecontext.Testing
Full repo build (net472 + net10.0) clean with 0 warnings.
AppHostSupport_Testspass.Notes
Type-system tightening only — no runtime behavior change. The
#nullable enable annotationsscoping inNodeLauncher.cs/DetouredNodeLauncher.csis a deliberately minimal alternative to converting those files to#nullable enablewholesale.