Debugging not working with XCode 12 selected

[DavidKarlas]

Description

In VSMac, we are using vsdbg(same as Omnisharp) to debug .NET Core applications... We have unit tests, but ever since bumping XCode from 11 to 12, debugging started failing... So here are repro steps:

1. sudo xcode-select -s /Applications/Xcode_12.app
2. mkdir xcodeTestProj
3. cd xcodeTestProj
4. dotnet new console
5. dotnet publish --runtime osx-x64
6. code .
7. create launch.json via VSCode, and change:

• "program": "${workspaceFolder}/bin/Debug/net5.0/xcodeTestProj.dll",
• to
• "program": "${workspaceFolder}/bin/Debug/net5.0/osx-x64/publish/xcodeTestProj.dll",

7. Start debugging
8. Observe Debug Console print Unable to attach to CoreCLR. Unknown Error: 0x80131c3c

Now try all steps, but change step 1 to sudo xcode-select -s /Applications/Xcode_11.app(notice change of Xcode version), it will work fine.

I tried to change to not use published version... But when tests are executing they fail either wrong variables values are reported or “Unable to evaluate expression because the code is optimized o...”.(Only when using XCode 12, fine with XCode 11). I believe underlining problem is same, hence I suggest trying debugging published app since its easier repro...

Im not sure how is selecting XCode 12 vs 11 effecting debugging of CoreCLR, but it does, I suspect its something related to lldb or some libraries used...

Configuration

• Which version of .NET is the code running on? 3.1, but also tried with 5.0
• What OS and version, and what distro if applicable? macOs
• What is the architecture (x64, x86, ARM, ARM64)? x64
• Do you know whether it is specific to that configuration? Yes(macOs)
• If you're using Blazor, which web browser(s) do you see this issue in? N/A

Regression?

No.

Other information

We have to disable .NET Core unit tests for until this is resolved, but I also believe this will effect users when doing some complex debugging.

Tagging subscribers to this area: @tommcdon
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[tommcdon]

@hoyosjs
FYI @caslan

[mrward]

Looks like we may be seeing some customers running into this problem when debugging in VS Mac with Xcode 12 installed.

• https://developercommunity.visualstudio.com/content/problem/1190334/unable-to-attach-to-coreclr-unknown-error-0x80131c.html - Xcode 12 being used here.

• https://developercommunity.visualstudio.com/content/problem/1189274/unable-to-debug-azure-function-locally-on-mac.html - Not confirmed Xcode 12 use here.

[c-lamont]

I can confirm this workaround.

1. Download Xcode 11: https://download.developer.apple.com/Developer_Tools/Xcode_11.7/Xcode_11.7.xip
2. Unzip and rename to Xcode_11
3. Move it to your Applications folder
4. Open terminal
5. Go to root: cd /
6. Run: sudo xcode-select -s /Applications/Xcode_11.app

Now everything works for me.

[TheCodeTraveler]

Thanks!

Download Xcode

The direct link to the Xcode 11.7 file didn't work for me.

In case anyone else is having trouble, go to Apple's More Downloads for Apple Developers page and search Xcode 11.7 👍

[DavidKarlas]

Hi @tommcdon @hoyosjs,

Im wonder how could priority on this be increased so someone takes a look at this since more and more developers will start switching to XCode 12 since it was released last week, and milestone .NET 6 feels too far away... At first I though this would only be problem for unit tests but looks like its effecting also developers...

Regards,
David

[borzuyehr]

@c-lamont and @brminnick solution worked for me as a workaround as well. Just to mention, my initial workaround was to Dockerize my .NET core app and run it in a Linux container. Just in case the above workaround does not work for others out there.

[hoyosjs]

@DavidKarlas the milestone means that it will be completed in master first. If there's enough customer feedback, we take it to ship room for backport approval. I can imagine this fitting the requirements easily.

And sorry for the time it's taken me. I've had an avalanche of issues coming in and I tried getting XCode 12, but my Mac seems... a little hesitant to help here. With all of us working from home, I haven't been able to access a different device. I'll see if a teammate can help me out to repro this.

[DavidKarlas]

@hoyosjs Tnx for explaining, I just thought that milestone means it will have to wait few months... If you want me to do some testing/debugging let me know.

[mklement0]

Re workaround:

It seems that downloading and installing the "Command Line Developer Tools for Xcode 11.5" (*.dmg, contains an installer package (*.pkg), about 260MB) from https://developer.apple.com/download/more/ is sufficient (no need for Xcode 11 as a whole).

Once installed, switch to this version of the tools with sudo xcode-select -s /Library/Developer/CommandLineTools