[GHC] #15728: Program with safe array operations triggers debug runtime assertion

[GHC]

#15728: Program with safe array operations triggers debug runtime assertion
-------------------------------------+-------------------------------------
        Reporter:  osa1              |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Runtime System    |              Version:  8.6.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by bgamari):

 The assertion in question expects to see that the bits that we are about
 to return to the caller have been cleared with `0xaa` (since sanity
 checking is enabled). However, isn't quite the case,
 {{{
 #5  0x00000000008a0d6e in allocateMightFail (cap=0xc92500
 <MainCapability>, n=14) at rts/sm/Storage.c:978
 978         IF_DEBUG(sanity, ASSERT(*((StgWord8*)p) == 0xaa));
 >>> x/8a p
 0x4200105788:   0x420008da21    0xaaaaaaaaaaaaaaaa
 0x4200105798:   0xaaaaaaaaaaaaaaaa      0xaaaaaaaaaaaaaaaa
 0x42001057a8:   0xaaaaaaaaaaaaaaaa      0xaaaaaaaaaaaaaaaa
 0x42001057b8:   0xaaaaaaaaaaaaaaaa      0xaaaaaaaaaaaaaaaa
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15728#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler