[gcc r10-10075] Fortran: Fix for class defined operators [PR99125].

[gcc r10-10075] Fortran: Fix for class defined operators [PR99125].

[Harald Anlauf]

https://gcc.gnu.org/g:4cecfae4b57e052008e2febe25607d5e2cad5dbb

commit r10-10075-g4cecfae4b57e052008e2febe25607d5e2cad5dbb
Author: Paul Thomas <pault@gcc.gnu.org>
Date:   Sat Mar 13 11:39:57 2021 +0000

    Fortran: Fix for class defined operators [PR99125].
    
    2021-03-13  Paul Thomas  <pault@gcc.gnu.org>
    
    gcc/fortran
            PR fortran/99125
            * trans-array.c (gfc_conv_expr_descriptor): For deferred length
            length components use the ss_info string length instead of
            gfc_get_expr_charlen. Make sure that the deferred string length
            is a variable before assigning to it. Otherwise use the expr.
            * trans-expr.c (gfc_conv_string_length): Make sure that the
            deferred string length is a variable before assigning to it.
    
    gcc/testsuite/
            PR fortran/99125
            * gfortran.dg/alloc_deferred_comp_1.f90: New test.
    
    (cherry picked from commit 7987beec679898cfa75839551d55ae5234a216bd)

Diff:
---
 gcc/fortran/trans-array.c                           | 10 ++++++++--
 gcc/fortran/trans-expr.c                            |  2 +-
 gcc/testsuite/gfortran.dg/alloc_deferred_comp_1.f90 | 18 ++++++++++++++++++
 3 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
index 46fd1dda4c4..c0a43c33613 100644
--- a/gcc/fortran/trans-array.c
+++ b/gcc/fortran/trans-array.c
@@ -7722,15 +7722,21 @@ gfc_conv_expr_descriptor (gfc_se *se, gfc_expr *expr)
       /* Set the string_length for a character array.  */
       if (expr->ts.type == BT_CHARACTER)
 	{
-	  se->string_length =  gfc_get_expr_charlen (expr);
+	  if (deferred_array_component)
+	    se->string_length = ss_info->string_length;
+	  else
+	    se->string_length =  gfc_get_expr_charlen (expr);
+
 	  if (VAR_P (se->string_length)
 	      && expr->ts.u.cl->backend_decl == se->string_length)
 	    tmp = ss_info->string_length;
 	  else
 	    tmp = se->string_length;
 
-	  if (expr->ts.deferred)
+	  if (expr->ts.deferred && VAR_P (expr->ts.u.cl->backend_decl))
 	    gfc_add_modify (&se->pre, expr->ts.u.cl->backend_decl, tmp);
+	  else
+	    expr->ts.u.cl->backend_decl = tmp;
 	}
 
       /* If we have an array section or are assigning make sure that
diff --git a/gcc/fortran/trans-expr.c b/gcc/fortran/trans-expr.c
index d88ad2b293a..cb901437965 100644
--- a/gcc/fortran/trans-expr.c
+++ b/gcc/fortran/trans-expr.c
@@ -2471,7 +2471,7 @@ gfc_conv_string_length (gfc_charlen * cl, gfc_expr * expr, stmtblock_t * pblock)
 			     se.expr, build_zero_cst (TREE_TYPE (se.expr)));
   gfc_add_block_to_block (pblock, &se.pre);
 
-  if (cl->backend_decl)
+  if (cl->backend_decl && VAR_P (cl->backend_decl))
     gfc_add_modify (pblock, cl->backend_decl, se.expr);
   else
     cl->backend_decl = gfc_evaluate_now (se.expr, pblock);
diff --git a/gcc/testsuite/gfortran.dg/alloc_deferred_comp_1.f90 b/gcc/testsuite/gfortran.dg/alloc_deferred_comp_1.f90
new file mode 100644
index 00000000000..0fc54d5331c
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/alloc_deferred_comp_1.f90
@@ -0,0 +1,18 @@
+! { dg-do run }
+!
+! Test the fix for PR99125, where the array reference in the print
+! statement caused an ICE because the gimplifier complained about '0'
+! being used as an lvalue.
+!
+! Contributed by Gerhard Steinmetz  <gscfq@t-online.de>
+!
+program p
+   type t
+      character(:), allocatable :: a(:)
+   end type
+   type(t) :: x
+   character(8) :: c(3) = ['12 45 78','23 56 89','34 67 90']
+   x%a = c
+   if (any (x%a(2:3) .ne. ['23 56 89','34 67 90'])) stop 1
+   if (any (x%a(2:3)(4:5) .ne. ['56','67'])) stop 2 ! Bizarrely this worked.
+end