Looking at N1601.pdf, I see

R735 pointer-assignment-stmt is data-pointer-object [ (bounds-spec-
list) ] => data-target
or data-pointer-object (bounds-remapping-list ) => data-target
or proc-pointer-object => proc-target

And I see constraint C538:

"A pointer object that has the PROTECTED attribute and is accessed by
use association shall
not appear as (1) A pointer-object in a pointer-assignment-stmt..."

C538 doesn't forbid using a protected pointer as the target of a
pointer-assignment-stmt. But two (gfortran 4.4.0, Sun f90 8.3) out of
three compilers surveyed (ifort 10.1 is the third) disallow it. Am I
overlooking something? Thanks in advance.

%% cat p1.f90
module m
implicit none
integer, pointer, protected :: protected_pointer
end module m

Steven Correll <steven.correll@gmail.com> wrote:

I don't think you are overlooking anything. Seems to me like those two
compilers are though. C537 prohibits a protected nonpointer object from
being a target. Looks to me like those compilers overlooked the
"nonpointer" part.

The distinction makes sense (to me). If you set a pointer to point to a
nonpointer protected target, you would have just opened a potential way
for that protected object to be changed, possibly in contexts that are
impractical for the compiler to diagnose, thus subverting much of the
point of the protected attribute.