[ci-scan] Build break: Crossgen2 TypeLoadException 'Gen' from assembly 'b27077' generic explicit layout

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Build Information

Build: https://dev.azure.com/dnceng-public/public/_build/results?buildId=1582971
Build error leg or test failing: runtime-coreclr crossgen2 outerloop (definition 134) — R2R_CG2 Regression_4 leg. Crossgen2 aborts compiling test assembly b27077.

Pipeline: runtime-coreclr crossgen2 outerloop (definition 134), branch main. When Crossgen2 lays out the exception-info lookup table for assembly b27077, it throws a TypeLoadException: the type Gen is a generic type declared with explicit layout, which is invalid. Crossgen2 exits -1073740791 and the R2R_CG2 work item fails. This is a compile-time crossgen2 break, distinct from the runtime failures tracked elsewhere. Reproduces across source build 1582971 and follow-up build 1584221.

Error Details

Unhandled exception. Internal.TypeSystem.TypeSystemException+TypeLoadException: Failed to load type 'Gen' from assembly 'b27077' because generic types cannot have explicit layout
   at ILCompiler.DependencyAnalysis.ReadyToRun.ExceptionInfoLookupTableNode.LayoutMethodsWithEHInfo() in /_/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/ExceptionInfoLookupTableNode.cs:line 95
   at ILCompiler.DependencyAnalysis.ReadyToRun.ExceptionInfoLookupTableNode.ShouldSkipEmittingObjectNode(NodeFactory) in /_/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/ExceptionInfoLookupTableNode.cs:line 154
Crossgen2 failed with exitcode - -1073740791

Error Message

{
  "ErrorMessage": "Failed to load type 'Gen' from assembly 'b27077' because generic types cannot have explicit layout",
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Agentic workflow metadata (ci-failure-scan)

Workflow artifact: ci-failure-scan
Artifact kind: kbe-verification
Verified match count: 1 hits in failure.log
First build it occurred: 1582971
Related: #133216 (distinct Crossgen2 TypeLoadException on 'Negative002' / 'format is invalid')

Duplicate search

Searched open/closed Known Build Error issues and merged PRs for the Gen/b27077/explicit layout signature. Open #133216 tracks a distinct Crossgen2 TypeLoadException (Negative002, format is invalid); Build Analysis matches on the verbatim substring, so this explicit layout signature is filed separately. No fix PR has merged after the source build.

---

Filed by ci-failure-scan (detection only). ci-failure-fix walks open [ci-scan] KBEs and either opens a small fix PR or comments to loop in owners — it never disables the test.

Note

Generated by the CI Outer-Loop Failure Scanner agentic workflow (AI-generated content).

Generated by CI Outer-Loop Failure Scanner · opus48 · 457.6 AIC · ⌖ 13 AIC · ⊞ 20.7K · ◷

Report

Build	Repository	Test	Pull Request
1592131	dotnet/runtime	Regression_4.WorkItemExecution
1590362	dotnet/runtime	Regression_4.WorkItemExecution

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
1	2	2

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Tagging subscribers to this area: @dotnet/crossgen-contrib
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[VincentBu]

Failed in: runtime-coreclr outerloop 20260909.9

Failed tests:

R2R-CG2 linux x64 Checked no_tiered_compilation @ AzureLinux.3.Amd64.Open
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 linux x64 Checked @ AzureLinux.3.Amd64.Open
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 osx x64 Checked no_tiered_compilation @ OSX.15.Amd64.Open
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 osx x64 Checked @ OSX.15.Amd64.Open
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 linux x64 Checked @ (Alpine.324.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:alpine-3.24-helix-amd64@sha256:27b4b25f2c1dde8d0349818f8a93adc8e797cd1fb5f0cbac07089c25abdce49d
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 linux x64 Checked no_tiered_compilation @ (Alpine.324.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:alpine-3.24-helix-amd64@sha256:27b4b25f2c1dde8d0349818f8a93adc8e797cd1fb5f0cbac07089c25abdce49d
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 windows x86 Checked no_tiered_compilation @ Windows.10.Amd64.Open
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 windows x64 Checked @ Windows.Amd64.Open.rt
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 windows x64 Checked no_tiered_compilation @ Windows.Amd64.Open.rt
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 windows x86 Checked @ Windows.10.Amd64.Open
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 linux arm64 Checked no_tiered_compilation @ (Alpine.324.Arm64.Open)AzureLinux.3.Arm64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:alpine-3.24-helix-arm64v8@sha256:7229985457fd1fb60afe60d1550bc9ccf93c5d54d3429aba079f4de6a7ffe7cf
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 linux arm64 Checked @ (Alpine.324.Arm64.Open)AzureLinux.3.Arm64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:alpine-3.24-helix-arm64v8@sha256:7229985457fd1fb60afe60d1550bc9ccf93c5d54d3429aba079f4de6a7ffe7cf
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 linux arm64 Checked @ AzureLinux.3.Arm64.Open
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 linux arm64 Checked no_tiered_compilation @ AzureLinux.3.Arm64.Open
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 windows arm64 Checked @ Windows.11.Arm64.Open
- LoaderClassloaderGenerics.WorkItemExecution
R2R-CG2 windows arm64 Checked no_tiered_compilation @ Windows.11.Arm64.Open
- LoaderClassloaderGenerics.WorkItemExecution

Error message:

Unhandled exception. Internal.TypeSystem.TypeSystemException+TypeLoadException: Failed to load type 'Gen`1<System.__Canon>' from assembly 'Negative002' because the format is invalid
   at Internal.TypeSystem.ThrowHelper.ThrowTypeLoadException(ExceptionStringID, String, String) in /_/src/coreclr/tools/Common/TypeSystem/Common/ThrowHelper.cs:line 17
   at Internal.TypeSystem.MetadataFieldLayoutAlgorithm.ComputeInstanceLayout(DefType, InstanceLayoutKind) in /_/src/coreclr/tools/Common/TypeSystem/Common/MetadataFieldLayoutAlgorithm.cs:line 78
   at Internal.TypeSystem.DefType.ComputeInstanceLayout(InstanceLayoutKind) in /_/src/coreclr/tools/Common/TypeSystem/Common/DefType.FieldLayout.cs:line 505
   at ILCompiler.CompilerTypeSystemContext.EnsureLoadableTypeUncached(TypeDesc) in /_/src/coreclr/tools/Common/Compiler/CompilerTypeSystemContext.Validation.cs:line 371
   at ILCompiler.CompilerTypeSystemContext.EnsureLoadableType(TypeDesc) in /_/src/coreclr/tools/Common/Compiler/CompilerTypeSystemContext.Validation.cs:line 83
   at ILCompiler.CompilerTypeSystemContext.EnsureLoadableMethod(MethodDesc) in /_/src/coreclr/tools/Common/Compiler/CompilerTypeSystemContext.Validation.cs:line 230
   at ILCompiler.DependencyAnalysis.ReadyToRun.MethodFixupSignature..ctor(ReadyToRunFixupKind, MethodWithToken, Boolean) in /_/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/MethodFixupSignature.cs:line 37
   at ILCompiler.DependencyAnalysis.NodeFactory.<>c.<CreateNodeCaches>b__63_15(NodeFactory.MethodFixupKey) in /_/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRunCodegenNodeFactory.cs:line 485
   at ILCompiler.DependencyAnalysis.NodeFactory.CreateMethodEntrypoint(TypeAndMethod) in /_/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRunCodegenNodeFactory.cs:line 673
   at ILCompiler.DependencyAnalysis.NodeFactory.<EnumerateCompiledMethods>d__106.MoveNext() in /_/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRunCodegenNodeFactory.cs:line 707
   at ILCompiler.DependencyAnalysis.ReadyToRun.ExceptionInfoLookupTableNode.LayoutMethodsWithEHInfo() in /_/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/ExceptionInfoLookupTableNode.cs:line 95
   at ILCompiler.DependencyAnalysis.ReadyToRun.ExceptionInfoLookupTableNode.ShouldSkipEmittingObjectNode(NodeFactory) in /_/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/ExceptionInfoLookupTableNode.cs:line 154
   at ILCompiler.DependencyAnalysis.ReadyToRun.ReadyToRunHeaderNode.GetData(NodeFactory, Boolean) in /_/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/DependencyAnalysis/ReadyToRun/ReadyToRunHeaderNode.cs:line 184
   at ILCompiler.ObjectWriter.ObjectWriter.EmitObject(Stream, IReadOnlyCollection`1, IObjectDumper, Logger) in /_/src/coreclr/tools/Common/Compiler/ObjectWriter/ObjectWriter.cs:line 391
   at ILCompiler.DependencyAnalysis.ReadyToRunObjectWriter.EmitReadyToRunObjects(ReadyToRunContainerFormat, Logger) in /_/src/coreclr/tools/aot/ILCompiler.ReadyToRun/CodeGen/ReadyToRunObjectWriter.cs:line 197
   at ILCompiler.ReadyToRunCodegenCompilation.Compile(String) in /_/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/ReadyToRunCodegenCompilation.cs:line 447
   at ILCompiler.Program.RunSingleCompilation(Dictionary`2, InstructionSetSupport, String, Dictionary`2, HashSet`1, ReadyToRunCompilerContext, Logger) in /_/src/coreclr/tools/aot/crossgen2/Program.cs:line 728
   at ILCompiler.Program.Run() in /_/src/coreclr/tools/aot/crossgen2/Program.cs:line 343
   at ILCompiler.Crossgen2RootCommand.<>c__DisplayClass228_0.<.ctor>b__0(ParseResult) in /_/src/coreclr/tools/aot/crossgen2/Crossgen2RootCommand.cs:line 287
   at System.CommandLine.Invocation.InvocationPipeline.Invoke(ParseResult) in /_/src/command-line-api/src/System.CommandLine/Invocation/InvocationPipeline.cs:line 127
   at ILCompiler.Program.Main(String[] args) in /_/src/coreclr/tools/aot/crossgen2/Program.cs:line 1009
DOTNET_DbgEnableMiniDump is set and the createdump binary does not exist: /root/helix/work/correlation/crossgen2/createdump
Loader/classloader/generics/LoaderClassloaderGenerics/LoaderClassloaderGenerics.sh: line 258:  1603 Aborted                    (core dumped) $__Command
02:20:49
Crossgen2 failed with exitcode: 134