re PR c++/36741 (Bogus "large integer implicitly truncated" passing size_t constant to new)

2008-08-28  Dodji Seketeli  <dodji@redhat.com>

	PR c++/36741
	* tree.c (int_fits_type_p): Don't forget unsigned integers
	  of type sizetype which higher end word equals -1.

From-SVN: r139712

gcc/ChangeLog

+2008-08-28  Dodji Seketeli  <dodji@redhat.com>
+
+	PR c++/36741
+	* tree.c (int_fits_type_p): Don't forget unsigned integers
+	  of type sizetype which higher end word equals -1.
+
 2008-08-28  Ira Rosen  <irar@il.ibm.com>
 
 	* target.h (struct vectorize): Add new target builtin.

gcc/testsuite/ChangeLog

+2008-08-28  Dodji Seketeli  <dodji@redhat.com>
+
+	PR c++/36741
+	* g++.dg/other/new-size-type.C: New test.
+
 2008-08-28  Ira Rosen  <irar@il.ibm.com>
 
 	* lib/target-supports.exp (check_effective_target_vect_perm): New.

gcc/testsuite/g++.dg/other/new-size-type.C

+// Contributed by Dodji Seketeli <dodji@redhat.com>
+// Origin: PR c++/36741
+
+#include <stddef.h>
+const char*
+foo()
+{
+    return new char[~static_cast<size_t>(0)];// { dg-bogus "large" }
+}
+

gcc/tree.c

@@ -6319,6 +6319,21 @@ int_fits_type_p (const_tree c, const_tree type)
      for "unknown if constant fits", 0 for "constant known *not* to fit" and 1
      for "constant known to fit".  */
 
+  if (TREE_TYPE (c) == sizetype
+      && TYPE_UNSIGNED (TREE_TYPE (c))
+      && TREE_INT_CST_HIGH (c) == -1
+      && !TREE_OVERFLOW (c))
+      /* So c is an unsigned integer which type is sizetype.
+         sizetype'd integers are sign extended even though they are
+	 unsigned. If the integer value fits in the lower end word of c,
+	 and if the higher end word has all its bits set to 1, that
+	 means the higher end bits are set to 1 only for sign extension.
+	 So let's convert c into an equivalent zero extended unsigned
+	 integer.  */
+      c = force_fit_type_double (size_type_node,
+				 TREE_INT_CST_LOW (c),
+				 TREE_INT_CST_HIGH (c),
+				 false, false);
   /* Check if C >= type_low_bound.  */
   if (type_low_bound && TREE_CODE (type_low_bound) == INTEGER_CST)
     {