re PR c++/27210 (ICE on c++ template)

	PR c++/27210
	* cp-tree.h (cp_save_expr): New function.
	* init.c (build_new): Correct logic for zero-element array
	warning.  Use cp_save_expr.
	* tree.c (cp_save_expr): New function.
	PR c++/27210
	* g++.dg/warn/new1.C: New test.
	* g++.dg/template/new5.C: Likewise.

From-SVN: r113958

gcc/cp/ChangeLog

+2006-05-21  Mark Mitchell  <mark@codesourcery.com>
+
+	PR c++/27210
+	* cp-tree.h (cp_save_expr): New function.
+	* init.c (build_new): Correct logic for zero-element array
+	warning.  Use cp_save_expr.
+	* tree.c (cp_save_expr): New function.
+
 2006-05-21  Volker Reichelt  <reichelt@igpm.rwth-aachen.de>
 
 	PR c++/27398

gcc/cp/cp-tree.h

@@ -4336,6 +4336,7 @@ extern int cp_auto_var_in_fn_p			(tree,tree);
 extern tree fold_if_not_in_template		(tree);
 extern tree rvalue                              (tree);
 extern tree convert_bitfield_to_declared_type   (tree);
+extern tree cp_save_expr                        (tree);
    
 /* in typeck.c */
 extern int string_conv_p			(tree, tree, int);

gcc/cp/init.c

@@ -2088,9 +2088,22 @@ build_new (tree placement, tree type, tree nelts, tree init,
     {
       if (!build_expr_type_conversion (WANT_INT | WANT_ENUM, nelts, false))
 	pedwarn ("size in array new must have integral type");
-      nelts = save_expr (cp_convert (sizetype, nelts));
-      if (nelts == integer_zero_node)
-	warning (0, "zero size array reserves no space");
+      nelts = cp_save_expr (cp_convert (sizetype, nelts));
+      /* It is valid to allocate a zero-element array:
+
+	   [expr.new]
+
+	   When the value of the expression in a direct-new-declarator
+	   is zero, the allocation function is called to allocate an
+	   array with no elements.  The pointer returned by the
+	   new-expression is non-null.  [Note: If the library allocation
+	   function is called, the pointer returned is distinct from the
+	   pointer to any other object.]  
+
+	 However, that is not generally useful, so we issue a
+	 warning.  */
+      if (integer_zerop (nelts))
+	warning (0, "allocating zero-element array");
     }
 
   /* ``A reference cannot be created by the new operator.  A reference

gcc/cp/tree.c

@@ -2083,6 +2083,20 @@ cp_auto_var_in_fn_p (tree var, tree fn)
 	  && nonstatic_local_decl_p (var));
 }
 
+/* Like save_expr, but for C++.  */
+
+tree
+cp_save_expr (tree expr)
+{
+  /* There is no reason to create a SAVE_EXPR within a template; if
+     needed, we can create the SAVE_EXPR when instantiating the
+     template.  Furthermore, the middle-end cannot handle C++-specific
+     tree codes.  */
+  if (processing_template_decl)
+    return expr;
+  return save_expr (expr);
+}
+
 /* Initialize tree.c.  */
 
 void

gcc/testsuite/ChangeLog

+2006-05-21  Mark Mitchell  <mark@codesourcery.com>
+
+	PR c++/27210
+	* g++.dg/warn/new1.C: New test.
+	* g++.dg/template/new5.C: Likewise.
+
 2006-05-21  Roger Sayle  <roger@eyesopen.com>
 
 	* gcc.target/i386/20060512-1.c: Add -msse2 command line option.

gcc/testsuite/g++.dg/template/new5.C

+// PR c++/27210
+
+template <class foo> class junk {
+  void bar(int a)
+  {
+    unsigned char *c = new unsigned char[a*sizeof(foo)];
+  }
+};
+

gcc/testsuite/g++.dg/warn/new1.C

+void f() {
+  new int[0]; // { dg-warning "zero" }
+}