[fpc-devel] Question on IsMemoryManagerSet logic

[Christo Crause]

Trying to detect at unit initialization if a memory manager has been
installed (xtensa-freertos) fails on FreeRTOS target.  It appears that
IsMemoryManagerSet[1] always returns false for this target, even if a
custom memory manager has been installed.  Looking at the implementation of
IsMemoryManagerSet shows that it will always return false if either
HAS_MEMORYMANAGER or FPC_NO_DEFAULT_MEMORYMANAGER is defined, if none of
these are defined, it will check if the getmem & freememare different to
the system defined routines.

For FreeRTOS both HAS_MEMORYMANAGER and  FPC_NO_DEFAULT_MEMORYMANAGER are
defined, so it is impossible to detect if a custom memory manager has been
installed using IsMemoryManagerSet.

a) Am I using the correct approach to detect if a memory manager is
installed?  I want to check if it is safe to use GetMem/FreeMem.
b) Is there a reason for the behaviour of IsMemoryManagerSet?

[1] From rtl/inc/heap.inc:
function IsMemoryManagerSet:Boolean;
begin
{$ifdef HAS_MEMORYMANAGER}
  Result:=false;
{$else HAS_MEMORYMANAGER}
{$ifdef FPC_NO_DEFAULT_MEMORYMANAGER}
  Result:=false;
{$else not FPC_NO_DEFAULT_MEMORYMANAGER}
  IsMemoryManagerSet := (MemoryManager.GetMem<>@SysGetMem)
    or (MemoryManager.FreeMem<>@SysFreeMem);
{$endif notFPC_NO_DEFAULT_MEMORYMANAGER}
{$endif HAS_MEMORYMANAGER}
end;
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