[Bug fortran/46974] ICE with TRANSFER using a C_PTR entity

[sgk at troutmask dot apl.washington.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46974

--- Comment #2 from Steve Kargl <sgk at troutmask dot apl.washington.edu> 
2010-12-18 00:01:03 UTC ---
On Fri, Dec 17, 2010 at 11:15:44PM +0000, kargl at gcc dot gnu.org wrote:
> 
> Anyone know why this flag is needed?
> 

Well, the answer is to let simplify_transfer_[34].f90
in the testsuite to compile!  :-)

Given 

   program z
   use iso_c_binding
   type(c_ptr) m
   m = transfer(32512, m)
   m = transfer(32512, C_NULL_PTR)
   end program z

This patch compiles the above.

Index: simplify.c
===================================================================
--- simplify.c  (revision 167949)
+++ simplify.c  (working copy)
@@ -5954,6 +5954,11 @@ gfc_simplify_transfer (gfc_expr *source,
   if (source->expr_type == EXPR_FUNCTION)
     return NULL;

+  if ((mold->expr_type == EXPR_VARIABLE || mold->expr_type == EXPR_STRUCTURE)
+      && mold->ts.type == BT_DERIVED && mold->ts.u.derived
+      && strcmp(mold->ts.u.derived->name, "c_ptr") == 0)
+    return NULL;
+
   /* Calculate the size of the source.  */
   if (source->expr_type == EXPR_ARRAY
       && gfc_array_size (source, &tmp) == FAILURE)

The tree dump looks like

z ()
--More--(74%){
  void * m;

  {
    void * transfer.0;
    integer(kind=8) D.1524;
    integer(kind=8) D.1523;
    static integer(kind=4) C.1522 = 32512;
    integer(kind=8) D.1521;

    D.1521 = 4;
    D.1523 = 8;
    __builtin_memcpy ((void *) &transfer.0, (void *) &C.1522,
       MAX_EXPR <MIN_EXPR <D.1523, D.1521>, 0>);
    m = transfer.0;
  }
  {
    void * transfer.1;
    integer(kind=8) D.1530;
    integer(kind=8) D.1529;
    static void * C.1528 = 0B;
    static integer(kind=4) C.1527 = 32512;
    integer(kind=8) D.1526;

    D.1526 = 4;
    D.1529 = 8;
    __builtin_memcpy ((void *) &transfer.1, (void *) &C.1527,
       MAX_EXPR <MIN_EXPR <D.1529, D.1526>, 0>);
    m = transfer.1;
  }
}

So we are assigning a void * pointer to a void * pointer.  Not
sure this is the desired result.