Hello world,
with Fortran 2018, recursive is becoming the default. This will likely
have a serious impact on many user codes, which often declare large
arrays which could then overflow stacks, leading to segfaults without
further explanation.
What could we do? A few options, not all mutally exclusive.
We could extend -fmax-stack-var-size so it allocates memory
from the heap in recursive procedures, too, and set this to
some default value. Of course, it would also have to free them
afterwards, but we manage that for allocatable arrays already.
We could warn when large arrays with sizes known at compile time
are translated.
We could use -fsplit-stack by default. How reliable is that
option? Can it be used, for example, with -fopenmp?
Is it available on all (relevant) platforms?
One drawback would be that this would allow for infinite
recursions to go on for much longer.
A -fcheck=stack option could be added (implemented similar to
-fsplit-stack), to be included in -fcheck=all, which would abort
with a sensible error message instead of a segfault.
Other ideas / options?
Regards
Thomas
