re PR fortran/67939 (ICE on using data with negative substring range)

2015-10-21  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/67939
	* data.c (create_character_initializer): Deal with zero length string.


2015-10-21  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/67939
	* gfortran.dg/pr67939.f90: New test.

From-SVN: r229153

gcc/fortran/ChangeLog

+2015-10-21  Steven G. Kargl  <kargl@gcc.gnu.org>
+
+	PR fortran/67939
+	* data.c (create_character_initializer): Deal with zero length string.
+
 2015-10-19  Steven G. Kargl  <kargl@gcc.gnu.org>
 
 	* resolve.c (gfc_verify_binding_labels): Check for NULL pointer.

gcc/fortran/data.c

@@ -104,7 +104,7 @@ static gfc_expr *
 create_character_initializer (gfc_expr *init, gfc_typespec *ts,
 			      gfc_ref *ref, gfc_expr *rvalue)
 {
-  int len, start, end;
+  int len, start, end, tlen;
   gfc_char_t *dest;
   bool alloced_init = false;
 	    
@@ -162,12 +162,22 @@ create_character_initializer (gfc_expr *init, gfc_typespec *ts,
   else
     len = rvalue->value.character.length;
 
-  if (len > end - start)
+  tlen = end - start;
+  if (len > tlen)
     {
-      gfc_warning_now (0, "Initialization string starting at %L was "
-		       "truncated to fit the variable (%d/%d)",
-		       &rvalue->where, end - start, len);
-      len = end - start;
+      if (tlen < 0)
+	{
+	  gfc_warning_now (0, "Unused initialization string at %L because "
+			   "variable has zero length", &rvalue->where);
+	  len = 0;
+	}
+      else
+	{
+	  gfc_warning_now (0, "Initialization string at %L was truncated to "
+			   "fit the variable (%d/%d)", &rvalue->where,
+			   tlen, len);
+	  len = tlen;
+	}
     }
 
   if (rvalue->ts.type == BT_HOLLERITH)
@@ -181,7 +191,7 @@ create_character_initializer (gfc_expr *init, gfc_typespec *ts,
 	    len * sizeof (gfc_char_t));
 
   /* Pad with spaces.  Substrings will already be blanked.  */
-  if (len < end - start && ref == NULL)
+  if (len < tlen && ref == NULL)
     gfc_wide_memset (&dest[start + len], ' ', end - (start + len));
 
   if (rvalue->ts.type == BT_HOLLERITH)

gcc/testsuite/ChangeLog

+2015-10-21  Steven G. Kargl  <kargl@gcc.gnu.org>
+
+	PR fortran/67939
+	* gfortran.dg/pr67939.f90: New test.
+
 2015-10-21  Aditya Kumar  <aditya.k7@samsung.com>
 	    Sebastian Pop  <s.pop@samsung.com>
 

gcc/testsuite/gfortran.dg/pr67939.f90

+! { dg-do compile }
+! PR fortran/67939
+! Original code by Gerhard Steinmetz
+! gerhard dot steinmetz dot fortran at t-online dot de
+!
+program p
+   character(100) :: x
+   data x(998:99) /'ab'/   ! { dg-warning "Unused initialization string" }
+   call a
+end
+
+subroutine a
+   character(2) :: x
+   data x(:-1) /'ab'/      ! { dg-warning "Unused initialization string" }
+end subroutine a
+
+subroutine b
+   character(8) :: x
+   data x(3:1) /'abc'/     ! { dg-warning "Unused initialization string" }
+end subroutine b
+