Fix NativeAOT assembly name mangling collisions by Copilot · Pull Request #130012 · dotnet/runtime

Copilot · 2026-06-30T01:13:40Z

Summary of changes

NativeAOT could generate duplicate mangled type names when different assembly names sanitized to the same C identifier, causing ILCompiler to fail with a duplicate-key exception.

Deterministically computes mangled assembly name prefixes from the compiler context’s input/reference assembly simple names.
Keys mangled assembly prefixes by assembly simple name strings without loading all reference assemblies.
Uses existing disambiguation for sanitized non-System.Private.* assembly names.
Preserves System.Private.* → S.P.* mangling without disambiguation.
Adds end-to-end NativeAOT regression coverage under src/tests with colliding assembly names (A.B and A_B).

Validation

Baseline ./build.sh clr+libs+host
./build.sh clr+libs+host
./build.sh clr.aot+libs -rc Release -lc Release
src/tests/build.sh -nativeaot -test:nativeaot/SmokeTests/AssemblyNameCollision/AssemblyNameCollision.csproj x64 release
artifacts/tests/coreclr/linux.x64.Release/nativeaot/SmokeTests/AssemblyNameCollision/AssemblyNameCollision.sh

PR Checklist

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dotnet-policy-service · 2026-06-30T01:30:43Z

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Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>

MichalStrehovsky

@copilot

Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>

Copilot · 2026-06-30T06:10:43Z

@copilot

Addressed the review feedback in b4734ac89: the mangler now keys by EcmaAssembly, and the unit test was replaced with an end-to-end NativeAOT test under src/tests.

MichalStrehovsky

@copilot

Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>

MichalStrehovsky · 2026-07-02T03:27:38Z

@copilot

2026-06-30T09:09:11.7112339Z CSC : warning CS2008: No source files specified. [/__w/1/s/src/tests/nativeaot/SmokeTests/AssemblyNameCollision/AssemblyWithDot/AssemblyWithDot.csproj] [/__w/1/s/src/tests/build.proj]
2026-06-30T09:09:11.7113082Z CSC : warning CS2008: No source files specified. [/__w/1/s/src/tests/nativeaot/SmokeTests/AssemblyNameCollision/AssemblyWithUnderscore/AssemblyWithUnderscore.csproj] [/__w/1/s/src/tests/build.proj]
2026-06-30T09:09:11.7114176Z CSC : warning CS2008: No source files specified. [/__w/1/s/src/tests/nativeaot/SmokeTests/AssemblyNameCollision/AssemblyNameCollision.csproj] [/__w/1/s/src/tests/build.proj]

Also move the test out of SmokeTests to a src/tests/nativeaot/Regressions directory. Rename AssemblyNameCollision to Runtime112629.

Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>

Copilot · 2026-07-02T04:09:21Z

@copilot

2026-06-30T09:09:11.7112339Z CSC : warning CS2008: No source files specified. [/__w/1/s/src/tests/nativeaot/SmokeTests/AssemblyNameCollision/AssemblyWithDot/AssemblyWithDot.csproj]...

Addressed in 849c26f: moved the test to src/tests/nativeaot/Regressions/Runtime112629, renamed the main project/source to Runtime112629, and added explicit Compile items so the test projects no longer produce CS2008 empty-source warnings.

Removed OutputType property from the project file.

Copilot

Pull request overview

This PR updates NativeAOT’s name mangling to avoid collisions when different assembly simple names sanitize to the same C identifier, and adds a regression test scenario with colliding assembly names.

Changes:

Add cached, deterministic mangling for assembly-name prefixes to avoid sanitized-name collisions across input/reference assemblies.
Update type-name mangling to use the new mangled assembly prefix.
Add a NativeAOT regression test that references two assemblies whose names collide when sanitized (A.B vs A_B).

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/coreclr/tools/Common/Compiler/NativeAotNameMangler.cs	Adds deterministic disambiguation/caching for mangled assembly prefixes and uses it when building mangled type names.
src/tests/nativeaot/Regressions/Runtime112629/Runtime112629.csproj	Adds a new NativeAOT regression test project referencing two colliding-name assemblies.
src/tests/nativeaot/Regressions/Runtime112629/Runtime112629.cs	Implements the regression scenario that exercises two assemblies whose names sanitize to the same identifier.
src/tests/nativeaot/Regressions/Runtime112629/AssemblyWithDot/AssemblyWithDot.csproj	Adds helper library project with assembly name `A.B`.
src/tests/nativeaot/Regressions/Runtime112629/AssemblyWithDot/TestType.cs	Defines a simple type to validate correct binding to `A.B`.
src/tests/nativeaot/Regressions/Runtime112629/AssemblyWithUnderscore/AssemblyWithUnderscore.csproj	Adds helper library project with assembly name `A_B`.
src/tests/nativeaot/Regressions/Runtime112629/AssemblyWithUnderscore/TestType.cs	Defines a simple type to validate correct binding to `A_B`.

Copilot

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <CLRTestPriority>0</CLRTestPriority>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="Runtime112629.cs" />
+    <ProjectReference Include="AssemblyWithDot\AssemblyWithDot.csproj" Aliases="AssemblyWithDot" />
+    <ProjectReference Include="AssemblyWithUnderscore\AssemblyWithUnderscore.csproj" Aliases="AssemblyWithUnderscore" />
+  </ItemGroup>
+</Project>


+            static bool IsSystemPrivateAssemblyName(string assemblyName)
+            {
+                return assemblyName.StartsWith("System.Private.", StringComparison.Ordinal);
+            }


+        private Utf8String GetMangledAssemblyName(EcmaAssembly assembly)
+        {
+            string assemblyName = assembly.GetName().Name;
+            lock (this)
+            {
+                if (_mangledAssemblyNames.TryGetValue(assemblyName, out Utf8String mangledName))
+                    return mangledName;
+
+                return ComputeMangledAssemblyName(assemblyName, (CompilerTypeSystemContext)assembly.Context);


Initial plan

16e14ac

Copilot AI assigned Copilot and MichalStrehovsky Jun 30, 2026

Copilot AI requested review from Copilot and removed request for Copilot June 30, 2026 01:13

Copilot started work on behalf of MichalStrehovsky June 30, 2026 01:14 View session

github-actions Bot added the area-NativeAOT-coreclr label Jun 30, 2026

Fix NativeAOT assembly name disambiguation

cb840f1

Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>

Copilot AI requested review from Copilot and removed request for Copilot June 30, 2026 01:52

Copilot AI changed the title ~~[WIP] Fix AOT compilation error related to duplicate keys~~ Fix NativeAOT assembly name mangling collisions Jun 30, 2026

Copilot finished work on behalf of MichalStrehovsky June 30, 2026 01:54

Copilot AI requested a review from MichalStrehovsky June 30, 2026 01:54

MichalStrehovsky reviewed Jun 30, 2026

View reviewed changes

Comment thread src/coreclr/tools/Common/Compiler/NativeAotNameMangler.cs Outdated

Comment thread src/coreclr/tools/aot/ILCompiler.Compiler.Tests/ILCompiler.Compiler.Tests.csproj Outdated

Copilot started work on behalf of MichalStrehovsky June 30, 2026 05:38 View session

Address NativeAOT mangling review feedback

d3d11d8

Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>

Copilot AI requested review from Copilot and removed request for Copilot June 30, 2026 06:09

Copilot finished work on behalf of MichalStrehovsky June 30, 2026 06:11

Copilot AI requested a review from MichalStrehovsky June 30, 2026 06:11

MichalStrehovsky reviewed Jun 30, 2026

View reviewed changes

Comment thread src/coreclr/tools/Common/Compiler/NativeAotNameMangler.cs Outdated

Comment thread ...iler.Compiler.Tests/ILCompiler.Compiler.Tests.Assets/ILCompiler.Compiler.Tests.Assets.csproj Outdated

Comment thread src/tests/nativeaot/Regressions/Runtime112629/Runtime112629.csproj

Copilot started work on behalf of MichalStrehovsky June 30, 2026 07:45 View session

Address NativeAOT mangling review feedback

8e19dd9

Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>

Copilot AI requested review from Copilot and removed request for Copilot June 30, 2026 08:30

Align NativeAOT mangling simple-name comparer

81a70d3

Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>

Copilot AI requested review from Copilot and removed request for Copilot June 30, 2026 08:36

Copilot finished work on behalf of MichalStrehovsky June 30, 2026 08:37

Copilot AI requested a review from MichalStrehovsky June 30, 2026 08:37

build-analysis Bot mentioned this pull request Jun 30, 2026

The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#3008

Open

3 tasks

Copilot started work on behalf of MichalStrehovsky July 2, 2026 03:28 View session

Move NativeAOT assembly collision regression test

849c26f

Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>

Copilot AI requested review from Copilot and removed request for Copilot July 2, 2026 04:08

Copilot finished work on behalf of MichalStrehovsky July 2, 2026 04:10

Add Xunit test for TestEntryPoint method

3e86095

Copilot AI review requested due to automatic review settings July 2, 2026 06:24

Remove OutputType from Runtime112629.csproj

564e901

Removed OutputType property from the project file.

Copilot started reviewing on behalf of MichalStrehovsky July 2, 2026 06:24 View session

Copilot AI reviewed Jul 2, 2026

View reviewed changes

Refactor TestEntryPoint to use assertions

bca9aef

Copilot AI review requested due to automatic review settings July 3, 2026 03:57

Copilot started reviewing on behalf of MichalStrehovsky July 3, 2026 03:57 View session

Copilot AI reviewed Jul 3, 2026

View reviewed changes

build-analysis Bot mentioned this pull request Jul 3, 2026

ILC failing with exit code 139 for risc-v build #130145

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Copilot AI commented Jun 30, 2026 •

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