ERL-1076: Unsafe receive optimization causes bug in socket.erl

[OTP-Maintainer]

Original reporter: bjorn
Affected version: OTP-22.1
Component: compiler
Migrated from: https://bugs.erlang.org/browse/ERL-1076

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The compiler does an unsafe optimization of the code of the following lines in {{socket}}:

https://github.com/erlang/otp/blob/f3e3ceb55/erts/preloaded/src/socket.erl#L2207-L2239

The compiler will apply the optimization that avoids scanning the entire message. In this function, the optimization is unsafe because the receive marker will be set, but the function can return without entering the {{receive}}.

This optimization causes the bug in {{socket}} described by this email to Erlang Questions:

http://erlang.org/pipermail/erlang-questions/2019-October/098591.html

[OTP-Maintainer]

bjorn said:

https://github.com/erlang/otp/pull/2434

[OTP-Maintainer]

bjorn said:

There is another bug in the run-time system. Here are the details:

http://erlang.org/pipermail/erlang-questions/2019-October/098660.html

[OTP-Maintainer]

g-andrade said:

As a nitpick, I would suggest editing the link to the code excerpt in the description and refer to a specific commit[*], so that it doesn't risk pointing to a different piece of code in the future (it's currently pointing to `master`.)

(I've shot myself in the foot more than once with this sort of thing.)

[*]: https://github.com/erlang/otp/blob/f3e3ceb55/erts/preloaded/src/socket.erl#L2207-L2239