Dear all,

the attached patch fixes issues exhibited by the testcase in comment#19 of PR55978.

First, when passing an allocatable optional dummy array to an optional dummy,
we need to prevent accessing the data component of the array when the argument
is not present, and pass a null pointer instead.  This is straightforward.

Second, the case of a missing pointer optional dummy array should have worked,
but the presence check surprisingly did not work as expected at -O0 or -Og,
but at higher optimization levels.  Interestingly, the dump-tree looked right,
but running under gdb or investigating the assembler revealed that the order
of tests in a logical AND expression was opposed to what the tree-dump looked
like.  Replacing TRUTH_AND_EXPR by TRUTH_ANDIF_EXPR and checking the optimized
dump confirmed that this does fix the issue.

Note that the tree-dump is not changed by this replacement.  Does this mean
thar AND and ANDIF currently are not differentiated at this level?

Regtested on x86_64-pc-linux-gnu.  OK for mainline?

Would it be ok to backport this to 14-branch, too?

Thanks,
Harald