[gcc(refs/users/mikael/heads/pr126895_v01)] fortran: Make IS_CONTIGUOUS true for assumed-rank scalars [PR126895]

https://gcc.gnu.org/g:559861d6562f9bd42073a29a379bb24a128a5dc8

commit 559861d6562f9bd42073a29a379bb24a128a5dc8
Author: Mikael Morin <[email protected]>
Date:   Sat Aug 15 21:54:06 2026 +0200

    fortran: Make IS_CONTIGUOUS true for assumed-rank scalars [PR126895]
    
    If the argument to IS_CONTIGUOUS is an assumed-rank variable, add a
    condition making the intrinsic return true if the variable rank is zero at
    execution time.  With the testcase, the function returned false regardless
    of the rank, because of a check of the span against the element size that
    compared unequal.
    
            PR fortran/126895
    
    gcc/fortran/ChangeLog:
    
            * trans-intrinsic.cc (gfc_conv_is_contiguous_expr): If the argument
            to IS_CONTIGUOUS is an assumed-rank variable, add a conditional
            making the value true if the runtime rank is zero.
    
    gcc/testsuite/ChangeLog:
    
            * gfortran.dg/is_contiguous_7.f90: New test.

Diff:
---
 gcc/fortran/trans-intrinsic.cc                |  9 +++++++++
 gcc/testsuite/gfortran.dg/is_contiguous_7.f90 | 26 ++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/gcc/fortran/trans-intrinsic.cc b/gcc/fortran/trans-intrinsic.cc
index 69a6034b3d38..31d81e517e72 100644
--- a/gcc/fortran/trans-intrinsic.cc
+++ b/gcc/fortran/trans-intrinsic.cc
@@ -2400,6 +2400,15 @@ gfc_conv_is_contiguous_expr (gfc_se *se, gfc_expr *arg)
 				  convert (boolean_type_node, se->expr));
     }
 
+  if (as && as->type == AS_ASSUMED_RANK)
+    {
+      tree rank = gfc_conv_descriptor_rank_get (desc);
+      tree scalar = fold_build2_loc (input_location, EQ_EXPR, boolean_type_node,
+				     rank, gfc_rank_cst[0]);
+      se->expr = fold_build2_loc (input_location, TRUTH_ORIF_EXPR,
+				  TREE_TYPE (se->expr), scalar, se->expr);
+    }
+
   gfc_free_ss_chain (ss);
 }
 
diff --git a/gcc/testsuite/gfortran.dg/is_contiguous_7.f90 b/gcc/testsuite/gfortran.dg/is_contiguous_7.f90
new file mode 100644
index 000000000000..806f1f318744
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/is_contiguous_7.f90
@@ -0,0 +1,26 @@
+! { dg-do run }
+!
+! PR fortran/126895
+! The IS_CONTIGUOUS intrinsic used to erroneously return FALSE for pointer
+! assumed-rank dummies associated with a scalar value.
+
+program prog
+  implicit none
+  type :: t
+    integer :: c1
+  end type
+  type, extends(t) :: u
+    integer :: c2
+  end type
+  type(t), target :: x
+  type(u), target :: y
+  call s1(x, 1)
+  call s1(y, 2)
+contains
+  subroutine s1(a, e)
+    class(t), pointer, intent(in) :: a(..)
+    integer, value :: e
+    !print *, is_contiguous(a)
+    if (.not. is_contiguous(a)) error stop e
+  end subroutine
+end program