[gcc r10-9181] This patch fixes PRs 96100 and 96101.

[gcc r10-9181] This patch fixes PRs 96100 and 96101.

[Paul Thomas]

https://gcc.gnu.org/g:47c1d976146913fad43688d45727d0038de174c7

commit r10-9181-g47c1d976146913fad43688d45727d0038de174c7
Author: Paul Thomas <pault@gcc.gnu.org>
Date:   Thu Aug 20 18:17:59 2020 +0100

    This patch fixes PRs 96100 and 96101.
    
    2020-08-20  Paul Thomas  <pault@gcc.gnu.org>
    
    gcc/fortran
            PR fortran/96100
            PR fortran/96101
            * trans-array.c (get_array_charlen): Tidy up the evaluation of
            the string length for array constructors. Avoid trailing array
            references. Ensure string lengths of deferred length components
            are set. For parentheses operator apply string  length to both
            the primary expression and the enclosed expression.
    
    gcc/testsuite/
            PR fortran/96100
            PR fortran/96101
            * gfortran.dg/char_length_23.f90: New test.
    
    (cherry picked from commit 300ef2fcc10e98359d14654be23bbb84a5d141e1)

Diff:
---
 gcc/fortran/trans-array.c                    | 21 +++++++++++++++++++--
 gcc/testsuite/gfortran.dg/char_length_23.f90 | 25 +++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
index befe7bb06ee..ad8772932e9 100644
--- a/gcc/fortran/trans-array.c
+++ b/gcc/fortran/trans-array.c
@@ -7019,7 +7019,12 @@ get_array_charlen (gfc_expr *expr, gfc_se *se)
       e = gfc_constructor_first (expr->value.constructor)->expr;
 
       gfc_init_se (&tse, NULL);
+
+      /* Avoid evaluating trailing array references since all we need is
+	 the string length.  */
       if (e->rank)
+	tse.descriptor_only = 1;
+      if (e->rank && e->expr_type != EXPR_VARIABLE)
 	gfc_conv_expr_descriptor (&tse, e);
       else
 	gfc_conv_expr (&tse, e);
@@ -7037,14 +7042,26 @@ get_array_charlen (gfc_expr *expr, gfc_se *se)
       gfc_add_modify (&se->pre, expr->ts.u.cl->backend_decl,
 		      tse.string_length);
 
+      /* Make sure that deferred length components point to the hidden
+	 string_length component.  */
+      if (TREE_CODE (tse.expr) == COMPONENT_REF
+	  && TREE_CODE (tse.string_length) == COMPONENT_REF
+	  && TREE_OPERAND (tse.expr, 0) == TREE_OPERAND (tse.string_length, 0))
+	e->ts.u.cl->backend_decl = expr->ts.u.cl->backend_decl;
+
       return;
 
     case EXPR_OP:
       get_array_charlen (expr->value.op.op1, se);
 
-      /* For parentheses the expression ts.u.cl is identical.  */
+      /* For parentheses the expression ts.u.cl should be identical.  */
       if (expr->value.op.op == INTRINSIC_PARENTHESES)
-	return;
+	{
+	  if (expr->value.op.op1->ts.u.cl != expr->ts.u.cl)
+	    expr->ts.u.cl->backend_decl
+			= expr->value.op.op1->ts.u.cl->backend_decl;
+	  return;
+	}
 
       expr->ts.u.cl->backend_decl =
 		gfc_create_var (gfc_charlen_type_node, "sln");
diff --git a/gcc/testsuite/gfortran.dg/char_length_23.f90 b/gcc/testsuite/gfortran.dg/char_length_23.f90
new file mode 100644
index 00000000000..e9ddbc7b8fd
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/char_length_23.f90
@@ -0,0 +1,25 @@
+! { dg-do compile }
+!
+! Test the fix for PRs 96100 and 96101.
+!
+! Contributed by Gerhardt Steinmetz  <gscfq@t-online.de>
+!
+program p
+   type t
+      character(:), allocatable :: c(:)
+   end type
+   type(t) :: x
+   character(:), allocatable :: w
+
+! PR96100
+   allocate(x%c(2), source = 'def')
+   associate (y => [x%c(1:1)])       ! ICE
+     print *,y
+   end associate
+
+! PR96101
+   associate (y => ([w(:)]))
+      print *, y                     ! ICE
+   end associate
+
+end