Duncan Coutts pushed to branch wip/dcoutts/issue-27284 at Glasgow Haskell Compiler / GHC

Commits:

• a476c9a2
  by Duncan Coutts at 2026-07-19T00:26:43+01:00

  Fix failing test GcStaticPointers for non-moving GC
  
  Minor mistake in asserting something before checking for that same
  thing.
  
  Specifically, Bdescr asserts HEAP_ALLOCED_GC, but Bdescr was being used
  prior to a guard that checks HEAP_ALLOCED_GC. The solution is just to
  move the use of Bdescr after the guard.
  
  Thanks to Simon Jakobi for identifying the problem.
  

1 changed file:

• rts/sm/NonMovingMark.c

Changes:

         // See Note [Weak pointer processing and the non-moving GC] in

         // MarkWeak.c

-        bdescr *key_bd = Bdescr((StgPtr) w->key);

-        bool key_in_nonmoving = HEAP_ALLOCED_GC(w->key) && block_get_flags(key_bd) & BF_NONMOVING;

+        bool key_in_nonmoving =

+               HEAP_ALLOCED_GC(w->key) &&

+               block_get_flags(Bdescr((StgPtr) w->key)) & BF_NONMOVING;

+

         if (!key_in_nonmoving || nonmovingIsNowAlive(w->key)) {

             nonmovingMarkLiveWeak(queue, w);

             did_work = true;