re PR fortran/81116 (Last character of allocatable-length string reset to blank in an assigment)

2017-08-16  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/81116
	* frontend-passes.c (realloc_string_callback): If expression is a
	concatenation, also check for dependency.
	(constant_string_length): Check for presence of symtree.

2017-08-16  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/81116
	* gfortran.dg/realloc_on_assignment_29.f90:  New test.

From-SVN: r251125

gcc/fortran/ChangeLog

+2017-08-16  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/81116
+	* frontend-passes.c (realloc_string_callback): If expression is a
+	concatenation, also check for dependency.
+	(constant_string_length): Check for presence of symtree.
+
 2017-08-13  Thomas Koenig  <tkoenig@gcc.gnu.org>
 
 	* gfortran.texi: Document format of unformatted sequential files.

gcc/fortran/frontend-passes.c

@@ -238,9 +238,9 @@ realloc_string_callback (gfc_code **c, int *walk_subtrees ATTRIBUTE_UNUSED,
     return 0;
 
   expr2 = gfc_discard_nops (co->expr2);
-  if (expr2->expr_type != EXPR_VARIABLE)
-    return 0;
 
+  if (expr2->expr_type == EXPR_VARIABLE)
+    {
       found_substr = false;
       for (ref = expr2->ref; ref; ref = ref->next)
 	{
@@ -252,6 +252,10 @@ realloc_string_callback (gfc_code **c, int *walk_subtrees ATTRIBUTE_UNUSED,
 	}
       if (!found_substr)
 	return 0;
+    }
+  else if (expr2->expr_type != EXPR_OP
+	   || expr2->value.op.op != INTRINSIC_CONCAT)
+    return 0;
   
   if (!gfc_check_dependency (expr1, expr2, true))
     return 0;
@@ -625,7 +629,8 @@ constant_string_length (gfc_expr *e)
 
   /* Return length of char symbol, if constant.  */
 
-  if (e->symtree->n.sym->ts.u.cl && e->symtree->n.sym->ts.u.cl->length
+  if (e->symtree && e->symtree->n.sym->ts.u.cl
+      && e->symtree->n.sym->ts.u.cl->length
       && e->symtree->n.sym->ts.u.cl->length->expr_type == EXPR_CONSTANT)
     return gfc_copy_expr (e->symtree->n.sym->ts.u.cl->length);
 

gcc/testsuite/ChangeLog

+2017-08-16  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/81116
+	* gfortran.dg/realloc_on_assignment_29.f90:  New test.
+
 2017-08-16  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/46091

gcc/testsuite/gfortran.dg/realloc_on_assign_29.f90

+! { dg-do run }
+! PR fortran/81116
+! The assignment was broken due to a missing temporary.
+! Original test case by Clive Page.
+
+program test10
+  implicit none
+  character(:), allocatable :: string
+  !
+  string = '1234567890'
+  string = string(1:5) // string(7:)
+  if (string /= '123457890') call abort
+end program test10