[GHC] #15975: semantics of concurrent program depends on -O level, -f[no-]omit-yields

[GHC]

#15975: semantics of concurrent program depends on -O level, -f[no-]omit-yields
-------------------------------------+-------------------------------------
        Reporter:  j.waldmann        |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  Research
                                     |  needed
       Component:  Runtime System    |              Version:  8.6.2
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Incorrect result  |  (amd64)
  at runtime                         |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by j.waldmann):

 (based on https://mail.haskell.org/pipermail/haskell-
 cafe/2018-November/130280.html )

 So my implicit assumption was
 that a run of the transaction manager (because "atomically")
 is also a yield - but this example shows that it isn't.

 If this is indeed the case, then this deserves to be mentioned
 in the documentation of Control.Concurrent.STM ?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15975#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler