[gcc r14-9086] Fortran: fix passing array component ref to polymorphic procedures

[Harald Anlauf <anlauf@gcc.gnu.org>]

https://gcc.gnu.org/g:14ba8d5b87acd5f91ab8b8c02165a0fd53dcc2f2

commit r14-9086-g14ba8d5b87acd5f91ab8b8c02165a0fd53dcc2f2
Author: Peter Hill <peter.hill@york.ac.uk>
Date:   Tue Feb 20 20:42:53 2024 +0100

    Fortran: fix passing array component ref to polymorphic procedures
    
            PR fortran/105658
    
    gcc/fortran/ChangeLog:
    
            * trans-expr.cc (gfc_conv_intrinsic_to_class): When passing an
            array component reference of intrinsic type to a procedure
            with an unlimited polymorphic dummy argument, a temporary
            should be created.
    
    gcc/testsuite/ChangeLog:
    
            * gfortran.dg/PR105658.f90: New test.
    
    Signed-off-by: Peter Hill <peter.hill@york.ac.uk>

Diff:
---
 gcc/fortran/trans-expr.cc              |  8 ++++++
 gcc/testsuite/gfortran.dg/PR105658.f90 | 50 ++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/gcc/fortran/trans-expr.cc b/gcc/fortran/trans-expr.cc
index 3506e4e4cb0b..118dfd7c9b23 100644
--- a/gcc/fortran/trans-expr.cc
+++ b/gcc/fortran/trans-expr.cc
@@ -1019,6 +1019,14 @@ gfc_conv_intrinsic_to_class (gfc_se *parmse, gfc_expr *e,
   tmp = gfc_typenode_for_spec (&class_ts);
   var = gfc_create_var (tmp, "class");
 
+  /* Force a temporary for component or substring references.  */
+  if (unlimited_poly
+      && class_ts.u.derived->components->attr.dimension
+      && !class_ts.u.derived->components->attr.allocatable
+      && !class_ts.u.derived->components->attr.class_pointer
+      && is_subref_array (e))
+    parmse->force_tmp = 1;
+
   /* Set the vptr.  */
   ctree = gfc_class_vptr_get (var);
 
diff --git a/gcc/testsuite/gfortran.dg/PR105658.f90 b/gcc/testsuite/gfortran.dg/PR105658.f90
new file mode 100644
index 000000000000..8aacecf806e7
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/PR105658.f90
@@ -0,0 +1,50 @@
+! { dg-do compile }
+! { dg-options "-Warray-temporaries" }
+! Test fix for incorrectly passing array component to unlimited polymorphic procedure
+
+module test_PR105658_mod
+   implicit none
+   type :: foo
+     integer :: member1
+     integer :: member2
+   end type foo
+contains
+   subroutine print_poly(array)
+     class(*), dimension(:), intent(in) :: array
+     select type(array)
+     type is (integer)
+       print*, array
+     type is (character(*))
+       print *, array
+     end select
+   end subroutine print_poly
+
+   subroutine do_print(thing)
+     type(foo), dimension(3), intent(in) :: thing
+     type(foo), parameter :: y(3) = [foo(1,2),foo(3,4),foo(5,6)]
+     integer :: i, j, uu(5,6)
+
+     call print_poly(thing%member1)   ! { dg-warning "array temporary" }
+     call print_poly(y%member2)       ! { dg-warning "array temporary" }
+     call print_poly(y(1::2)%member2) ! { dg-warning "array temporary" }
+
+     ! The following array sections work without temporaries
+     uu = reshape([(((10*i+j),i=1,5),j=1,6)],[5,6])
+     print *, uu(2,2::2)
+     call print_poly (uu(2,2::2))     ! no temp needed!
+     print *, uu(1::2,6)
+     call print_poly (uu(1::2,6))     ! no temp needed!
+   end subroutine do_print
+
+   subroutine do_print2(thing2)
+     class(foo), dimension(:), intent(in) :: thing2
+     call print_poly (thing2% member2) ! { dg-warning "array temporary" }
+   end subroutine do_print2
+
+   subroutine do_print3 ()
+     character(3) :: c(3) = ["abc","def","ghi"]
+     call print_poly (c(1::2))      ! no temp needed!
+     call print_poly (c(1::2)(2:3)) ! { dg-warning "array temporary" }
+   end subroutine do_print3
+
+end module test_PR105658_mod