[Bug fortran/93148] New: Pointer-function-result as LVALUE variable – function called multiple times with copy-in/out

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93148

            Bug ID: 93148
           Summary: Pointer-function-result as LVALUE variable – function
                    called multiple times with copy-in/out
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
                CC: tkoenig at gcc dot gnu.org
  Target Milestone: ---

Created attachment 47588
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47588&action=edit
Test case – compile & run

Found when looking at PR91640, cf.
https://gcc.gnu.org/ml/gcc-patches/2020-01/threads.html#00070

If one uses:
   call foo(f())

where foo takes a nonpointer dummy argument and f returns a pointer, the
pointer result is regarded as normal variable. (= gfc_is_variable == true).

Unfortunately, "f()" is called twice: once for the copy in and once for the
copy out.

Expected: It is only called once. See attached test case.