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…pendency reference assembly name When TrimDepsJsonLibrariesWithoutAssets=true (now default in SDK 11.x), DependencyContextBuilder.Build() calls runtimeLibraries.ToDictionary() which crashes if two libraries share the same name. The existing fix (f1c92d6) used GetUniqueLibraryName() for the project library name, which handles conflicts with NuGet package names and with _directReferences (since GetProjectDependencies() pre-registers them). However, _dependencyReferences (from ReferenceDependencyPaths) are NOT processed by GetProjectDependencies(). If the project name matches a dependency reference assembly name (and neither is a NuGet package), both get the same unique name, causing the ToDictionary crash. Fix: After computing the unique project library name, add it to _usedLibraryNames so that subsequent GetReferenceLibraryName() calls for dependency references with the same name produce a disambiguated name. Co-authored-by: marcpopMSFT <12663534+marcpopMSFT@users.noreply.github.com>
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marcpopMSFT
March 13, 2026 20:20
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I couldn't get a repro project even with copilot's help to repro the original issue. The original issue appears to be a duplicate name from the main project and a reference project. Looking at the code, the fix looks correct to me based on the explanation and at least one customer hit it. I think the risk is low so marking for review. |
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Pull request overview
Fixes a crash in GenerateDepsFile/DependencyContextBuilder.Build() where runtimeLibraries.ToDictionary(...) throws ArgumentException when the main project name collides with a dependency reference assembly name (from ReferenceDependencyPaths).
Changes:
- Ensure the computed project runtime library name is registered in
_usedLibraryNamesso subsequent reference libraries are disambiguated. - Add a regression unit test covering the project-name vs dependency-reference collision path via
WithDependencyReferences.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| src/Tasks/Microsoft.NET.Build.Tasks/DependencyContextBuilder.cs | Adds the project library name to _usedLibraryNames to avoid duplicate runtime library keys during ToDictionary. |
| src/Tasks/Microsoft.NET.Build.Tasks.UnitTests/GivenADependencyContextBuilder.cs | Adds a regression test to validate unique runtime library names when a dependency reference matches the project name. |
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https://developercommunity.visualstudio.com/t/Error-when-building-a-project-in-Microso/11045675
SDK 11.x enabled
TrimDepsJsonLibrariesWithoutAssets=trueby default, which introduced aruntimeLibraries.ToDictionary()call inDependencyContextBuilder.Build(). Any pre-existing duplicate library name inruntimeLibrariesnow causes anArgumentExceptioncrash instead of silently producing a malformed deps.json.A prior fix (
f1c92d6ca) addressed collisions between the project library name and NuGet package names (in_usedLibraryNamesat construction time) and_directReferences(pre-registered byGetProjectDependencies()). However,_dependencyReferences— assemblies fromReferenceDependencyPaths— are not processed byGetProjectDependencies(). If the project name matches one of these assembly names and neither appears as a NuGet package, both libraries receive the same name fromGetUniqueLibraryName, crashingToDictionary.Changes
DependencyContextBuilder.GetProjectRuntimeLibrary(): After computing the unique project library name viaGetUniqueLibraryName, add it to_usedLibraryNames. This ensures that when the reference loop subsequently callsGetReferenceLibraryName()for a_dependencyReferencewith the same base name, the name is detected as taken and a disambiguated name (e.g.,MyApp.Reference) is returned instead.GivenADependencyContextBuilder: Added regression testItHandlesProjectNameMatchingDirectReferenceAssemblyNameusingWithDependencyReferences(notWithDirectReferences) to exercise the specific code path that was unguarded — verifying no exception is thrown and the runtime library names are unique.