[Issue 24756] New: SIGRTMIN and SIGRTMIN+1 previous sigaction are being silently ignored when set by crt_constructor

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=24756

          Issue ID: 24756
           Summary: SIGRTMIN and SIGRTMIN+1 previous sigaction are being
                    silently ignored when set by crt_constructor
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P1
         Component: druntime
          Assignee: nobody at puremagic.com
          Reporter: contact at lsferreira.net

Libraries that implement crt0 constructor (crt_constructor) that set SIGRTMIN
and SIGRTMIN+1 get silently ignored after runtime initialisation as it
overrides without checking sigaction previous assignments.

As specified by POSIX, this should be checked and SIGRTMIN+n should have
runtime checks, and not hardcoded.

Runtime, at bare minimum, should assert when silently trying to override a
previous sigaction.

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