Support C++ extension to run on Mac M1 x64 emulator

[Satvik-B]

Type: General

Describe the bug

• OS and Version: macOS BigSur 11.1
• VS Code Version: 1.53 Insider
• C/C++ Extension Version: 1.1.3
• Other extensions you installed (and if the issue persists after disabling them):
• Architecture arm64 is not supported.
  Check the bottom right corner for the error
  

[sean-mcmanus]

The fix was made available a week ago at https://github.com/microsoft/vscode-cpptools/releases/tag/1.2.0-preview .

[benphelps]

While this fix does let the extension install, it's still running under Rosetta 2 which causes functionality to not align with what would be expected.

This can be seen here with a simple test,

VS Code Insiders is running natively, and you can prove this by checking the target clang reports, which is arm64-apple-darwin20.2.0.

However, the extensions binaries are still running under Rosetta 2, which causes anything spawned by them to also run under Rosetta 2. You can see this behavior in the current stable build of VS Code when checking the clang target, where it reports x86_64-apple-darwin20.2.0, even while running on an M1 processor.

The cpptools binary needs to be compiled natively for arm64 for everything to function correctly.

OS and Version: macOS Big Sur 11.1 (20C69)
VS Code Version: 1.53.0-insider
C/C++ Extension Version: v1.2.0-preview

[bobbrow]

The cpptools binary needs to be compiled natively for arm64 for everything to function correctly.

Yep, we have a feature tracking that. #6595. The current solution is just a workaround to unblock folks until we get set up to compile the binaries in our CI system.

[bobbrow]

@michelleangela will the cross compile feature work address the preprocessor stuff mentioned above? I was thinking this should already work if intelliSenseMode is set to an arm64 variant, so I was expecting it would even work today with the preview build @sean-mcmanus shared. Unless there is another preprocessor define we need to add to the .json files...

[sean-mcmanus]

How do were check? Where are those TARGET_CPU macros defined? With 1.2.0-preview I believe there was a bug where it could choose a non-ARM intelliSenseMode by default, but if the intelliSenseMode is se to *-arm64 then it would be expected to work.

[michelleangela]

The IntelliSenseMode value will default to the host architecture and if the extension can detect the default target architecture of the default installed compiler, it will change the IntelliSenseMode to that default target architecture.

Configuring the IntelliSense in c_cpp_properties.json to use a specific IntelliSenseMode "macos-clang-arm64" and adding --target arguments for arm64 to the compilerArgs are needed for the extension to get the marcos for arm64.

[michelleangela]

I changed the title of this issue to better reflect that the current way to support Mac M1 is to only enable installing the extension but not to enable the extension to run natively on arm64, which is a separate feature #6595.