crossgen2 crashes with CommandLineException when --strip-debug-info is passed via ExtraArgs on Apple mobile

[PureWeen]

Description

crossgen2 crashes with an unhandled System.CommandLine.CommandLineException when --strip-debug-info is passed on Apple mobile platforms (iOS, MacCatalyst). The System.CommandLine parser treats the next argument (--instruction-set:apple-m1) as a file path value for --strip-debug-info, then fails in AppendExpandedPaths trying to glob-expand it.

Exception

Microsoft.NET.CrossGen.targets(501,5): error :
Unhandled exception. System.CommandLine.CommandLineException: No files matching --strip-debug-info --instruction-set:apple-m1
   at System.CommandLine.Helpers.AppendExpandedPaths(Dictionary`2, String, Boolean)
   at System.CommandLine.Helpers.BuildPathDictionary(IReadOnlyList`1, Boolean)
   at System.CommandLine.Argument`1.<>c__DisplayClass8_0.<set_CustomParser>b__0(ArgumentResult, Object&)
   at System.CommandLine.Parsing.ArgumentResult.ValidateAndConvert(Boolean)
   at System.CommandLine.Parsing.CommandResult.ValidateAndAddDefaultResults(Boolean)
   at System.CommandLine.Parsing.ParseOperation.ValidateAndAddDefaultResults()
   at System.CommandLine.Parsing.ParseOperation.Parse()
   at System.CommandLine.Parsing.CommandLineParser.Parse(Command, IReadOnlyList`1, String, ParserConfiguration)
   at ILCompiler.Program.Main(String[] args)

Root Cause

dotnet/runtime#124604 added --strip-debug-info and --strip-inlining-info as boolean flags to crossgen2. dotnet/sdk#53514 passes these via PublishReadyToRunCrossgen2ExtraArgs in Microsoft.NET.CrossGen.targets for Apple mobile RIDs.

The issue appears to be that --strip-debug-info is not correctly declared as a zero-arity (boolean) option in crossgen2's System.CommandLine configuration. The parser consumes the next positional argument (--instruction-set:apple-m1) as its value and attempts to resolve it as a file path.

Reproduction

• SDK: 11.0.100-preview.3.26202.110 (first build containing sdk#53514)
• Target: net11.0-maccatalyst or net11.0-ios with CoreCLR (PublishReadyToRun=true)
• Platform: Apple ARM64

Previous SDK builds (26171.106 and earlier) do not have this issue as they predate sdk#53514.

Affected CI Builds

• dotnet/maui PR Compiler optimizing needed variable away #34799: Build #1365537 — maui-pr-devicetests, "Build Device Tests (CoreCLR)" step
• Only affects CoreCLR builds on Apple mobile RIDs; Mono builds are unaffected

Related PRs

• [clr-ios] Add options to strip inlining and debug info in Crossgen2 on Apple mobile #124604 — Added --strip-debug-info and --strip-inlining-info to crossgen2
• Add --strip-inlining-info and --strip-debug-info crossgen2 args for Apple mobile RIDs sdk#53514 — SDK targets to pass these args for Apple mobile RIDs

/cc @kotlarmilos

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Tagging subscribers to 'os-ios': @vitek-karas, @kotlarmilos, @steveisok, @akoeplinger
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[PureWeen]

Crossgen2 Response File Contents

RunReadyToRunCompiler (in dotnet/sdk) inherits from MSBuild ToolTask and overrides GenerateResponseFileCommands() → GenerateCrossgen2ResponseFile(). At runtime, MSBuild writes these contents to a temporary .rsp file, invokes crossgen2 as crossgen2 @/path/to/temp.rsp, and then deletes the temp file in a finally block. The binlog captures the response file contents (not the @file reference), which is why the temp .rsp is not in CI artifacts but the binlog is the authoritative record.

Here are the effective response file contents extracted from the binlog:

--targetos:maccatalyst
--targetarch:arm64
-O
--obj-format:macho
--strip-inlining-info
--strip-debug-info --instruction-set:apple-m1
--composite
--out:"/Users/cloudtest/vss/_work/1/s/artifacts/obj/Controls.DeviceTests/Release/net11.0-maccatalyst/maccatalyst-arm64/R2R/Microsoft.Maui.Controls.DeviceTests.r2r.o"
/Users/cloudtest/vss/_work/1/s/artifacts/obj/Controls.DeviceTests/Release/net11.0-maccatalyst/maccatalyst-arm64/linked/Microsoft.DotNet.XHarness.TestRunners.Common.dll
/Users/cloudtest/vss/_work/1/s/artifacts/obj/Controls.DeviceTests/Release/net11.0-maccatalyst/maccatalyst-arm64/linked/Microsoft.DotNet.XHarness.TestRunners.Xunit.dll
/Users/cloudtest/vss/_work/1/s/artifacts/obj/Controls.DeviceTests/Release/net11.0-maccatalyst/maccatalyst-arm64/linked/Microsoft.Extensions.Configuration.dll
...
(90+ more linked dlls)

Root cause

The bug is on this line:

--strip-debug-info --instruction-set:apple-m1

Crossgen2 reads the .rsp file line-by-line (via TryReadResponseFile()), treating each line as a single token. Because --strip-debug-info and --instruction-set:apple-m1 are on the same line, System.CommandLine receives the entire string --strip-debug-info --instruction-set:apple-m1 as one token. It cannot match it as a known option, so it falls through to the input-file argument where AppendExpandedPaths(..., strict: true) tries to glob-expand it as a file path and throws:

CommandLineException: No files matching --strip-debug-info --instruction-set:apple-m1

The MSBuild property feeding the extra args is:

PublishReadyToRunCrossgen2ExtraArgs = ;--strip-inlining-info;--strip-debug-info

Set at Microsoft.NET.CrossGen.targets (46,5).

It appears the extra args are appended via GenerateCrossgen2ResponseFile() in the SDK's RunReadyToRunCompiler.cs using StringBuilder.AppendLine() for each semicolon-delimited arg, but --strip-debug-info ends up on the same line as the subsequent --instruction-set:apple-m1 argument rather than getting its own line.

References

• Crossgen2 tool: microsoft.netcore.app.crossgen2.osx-arm64/11.0.0-preview.3.26202.110/tools/crossgen2
• Task exit code: 134
• Binlog: Build #1365537 artifact (Build.binlog, project ID 386, target 1004, task 651)
• SDK source: RunReadyToRunCompiler.cs — GenerateCrossgen2ResponseFile() builds the response file content