BlazorWasm AOT not requiring trimming

[agocke]

Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1320866
Build error leg or test failing: Wasm.Build.Tests.Blazor.NativeTests.BlazorWasm_CannotAOT_WithNoTrimming(config: Release)
Pull request: #125193

Error Message

Fill the error message using step by step known issues guidance.

{
  "ErrorMessage": "AOT is not supported without IL trimming",
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1320866
Error message validated: [AOT is not supported without IL trimming]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 3/5/2026 7:15:21 PM UTC

Report

Build	Definition	Test	Pull Request
1329602	dotnet/runtime	WBT-Workloads-MONO-ST-Wasm.Build.Tests.NativeBuildTests.WorkItemExecution	#125419
1333107	dotnet/runtime	WBT-Workloads-MONO-ST-Wasm.Build.Tests.NativeBuildTests.WorkItemExecution	#125192
1331285	dotnet/runtime	WBT-Workloads-MONO-ST-Wasm.Build.Tests.NativeBuildTests.WorkItemExecution	#125192
1329289	dotnet/runtime	WBT-NoWebcil-MONO-ST-Wasm.Build.Tests.NativeBuildTests.WorkItemExecution	#125250
1326416	dotnet/runtime	Wasm.Build.Tests.NativeBuildTests.AOTNotSupportedWithNoTrimming(config: Release, aot: True)	#125329
1326330	dotnet/runtime	Wasm.Build.Tests.Blazor.NativeTests.BlazorWasm_CannotAOT_WithNoTrimming(config: Release)	#125309
1320866	dotnet/runtime	WBT-NoWebcil-MONO-ST-Wasm.Build.Tests.Blazor.NativeTests.WorkItemExecution	#125193

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
1	6	7

[lewing]

Updated analysis (from binlog inspection)

My earlier analysis was incorrect about ILLink being involved. The binlog from the failing Helix run is truncated/corrupt — the MCP binlog tool reports:

Error when reading the file: System.IO.EndOfStreamException: Unable to read beyond the end of the stream.

This is the same "Error when reading the fil..." string visible in the test output. The actual sequence:

1. Test runs dotnet publish with PublishTrimmed=false + RunAOTCompilation=true
2. The dotnet process gets killed mid-build on Helix (the other test in the same work item got exit code 137 = SIGKILL/OOM)
3. The binlog is left truncated on disk
4. The test infrastructure sees no "Build failed" in stdout, falls back to parsing the binlog
5. The binlog reader hits EndOfStreamException and emits that as the only error message
6. The test asserts on "AOT is not supported without IL trimming" but only finds the file-reading error

This is an infrastructure flake — OOM kill on Helix before the build reaches the _WasmAotCompileApp target where the validation error would be emitted. With only 1 hit/month, this seems consistent with sporadic memory pressure on Helix machines.