re PR fortran/85641 (ICE with string concatenate)

2018-06-06  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/85641
	* frontend-passes.c (is_fe_temp): Add prototype.
	(realloc_string_callback): Early return for frontend-generated
	temporary.

2018-06-06  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/85641
	* gfortran.dg/realloc_on_assign_30.f90: New test.

From-SVN: r261248

gcc/fortran/ChangeLog

+2018-06-06  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/85641
+	* frontend-passes.c (is_fe_temp): Add prototype.
+	(realloc_string_callback): Early return for frontend-generated
+	temporary.
+
 2018-06-05  Cesar Philippidis  <cesar@codesourcery.com>
 
 	PR fortran/85701

gcc/fortran/frontend-passes.c

@@ -57,6 +57,8 @@ static bool has_dimen_vector_ref (gfc_expr *);
 static int matmul_temp_args (gfc_code **, int *,void *data);
 static int index_interchange (gfc_code **, int*, void *);
 
+static bool is_fe_temp (gfc_expr *e);
+
 #ifdef CHECKING_P
 static void check_locus (gfc_namespace *);
 #endif
@@ -254,6 +256,9 @@ realloc_string_callback (gfc_code **c, int *walk_subtrees ATTRIBUTE_UNUSED,
       || !expr1->ts.deferred)
     return 0;
 
+  if (is_fe_temp (expr1))
+    return 0;
+
   expr2 = gfc_discard_nops (co->expr2);
 
   if (expr2->expr_type == EXPR_VARIABLE)

gcc/testsuite/ChangeLog

+2018-06-06  Thomas Koenig  <tkoenig@gcc.gnu.org>
+
+	PR fortran/85641
+	* gfortran.dg/realloc_on_assign_30.f90: New test.
+
 2018-06-06  Carl Love  <cel@us.ibm.com>
 
 	* gcc.target/powerpc/builtins-3.c: Move tests requiring -mvsx

gcc/testsuite/gfortran.dg/realloc_on_assign_30.f90

+! { dg-do compile }
+! PR 85641 - this used to ICE due do infinite recursion.
+! Test case by Antony Lewis.
+program tester
+character(LEN=:), allocatable :: fields
+integer j
+character(LEN=4), parameter :: CMB_CL_Fields = 'TEBP'
+
+fields = ''
+j=1
+fields = fields // CMB_CL_Fields(j:j)
+
+end program tester