Add the ability to run tests on the standalone Dart VM under Address Sanitizer, Memory Sanitizer or Thread Sanitizer.

[rmacnak-google]

This is useful for finding issues when using foreign libraries through dart:ffi, such as use-after-free, use of initialized memory and data races.

This is also useful for pure Dart programs that might have data races through the use of shared fields.

Only available on 64-bit Linux.

https://clang.llvm.org/docs/AddressSanitizer.html
https://clang.llvm.org/docs/MemorySanitizer.html
https://clang.llvm.org/docs/ThreadSanitizer.html

[github-actions]

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[natebosch]

Can you edit the first comment on the PR to add some details about this change and the motivation? We can use the first comment to decide the content of the final commit message when this lands.

[natebosch]

We have had difficulty in the past using a direct exit call from the test runner, I don't think we should land another.

What are the scenarios where this would hang?

[rmacnak-google]

When the sanitizers exit the child, the parent was hanging. This is hacky, and probably the real issue is the consumer of the socket created between parent and child is failing to react to a disconnect, but I haven't found that code yet.

[natebosch]

Is the repro for this the one in #2577 ?

I started digging on that before the holidays but I hadn't made much progress. I'll spend some more time on it and see if I can make any headway. I'd prefer if we can land this without a potential call to exit but if we need something in the short term we can maybe leave it as a TODO.

[rmacnak-google]

Yeah. Anything that crashes or directly exits with -c exe should reproduce the issue. This is exit code forwarding is at least limited to -c exe and so won't affect the default way of running.