Erlang 26 regression: erlang:list_to_pid fails on 32-bit x86, ERTS_MAX_INTERNAL_PID_SERIAL is 0?

[leahneukirchen]

Describe the bug

The symptom of the bug is that erlang:list_to_pid doesn't work anymore, except for <0.N.0> (<0.0.0> is unit-tested...).

To Reproduce

2> erlang:list_to_pid("<0.0.1>").
               ** exception error: bad argument
     in function  list_to_pid/1
        called as list_to_pid("<0.0.1>")
        *** argument 1: not a textual representation of a pid

Expected behavior

It should return the PID <0.0.1>.

Affected versions

I can reproduce this on OTP 26.0.2/erts-14.0.2.

It worked on OTP 25/erts-13.2.2 and on 64-bit platforms.

Additional context

It turns out that ERTS_MAX_INTERNAL_PID_SERIAL is 0 now, is this intentional?

[rickard-green]

This is not a bug.

It turns out that ERTS_MAX_INTERNAL_PID_SERIAL is 0 now, is this intentional?

Yes. 32-bit emulators does not as of OTP 26 create pids for local processes with non-zero serial values.

list_to_pid/1 is intended to create a pid of a process that exist on the system. Since no local process on a 32-bit system can have a pid with a non-zero serial value it would be pointless with a list_to_pid/1 that could create such pid. Also note that list_to_pid/1 is purely intended for debugging and also clearly documented as such.

[leahneukirchen]

Thanks for the quick clarification, then I'll make sure that the Elixir test using this calls it with a 0 as serial.