re PR tree-optimization/16115 (double-destruction problem with argument passing…

re PR tree-optimization/16115 (double-destruction problem with argument passing via temporary (breaks auto_ptr))

        PR c++/16115
        * decl.c (grokparms): Give the PARM_DECL reference type if the
        parameter is passed by invisible reference.

From-SVN: r83609

gcc/cp/ChangeLog

+2004-06-24  Jason Merrill  <jason@redhat.com>
+
+	PR c++/16115
+	* decl.c (grokparms): Give the PARM_DECL reference type if the
+	parameter is passed by invisible reference.
+
 2004-06-24  Andreas Schwab  <schwab@suse.de>
 
 	* cp-tree.h (enum cp_storage_class): Remove trailing comma.

gcc/cp/decl.c

@@ -8224,6 +8224,13 @@ grokparms (cp_parameter_declarator *first_parm, tree *parms)
 
       if (type != error_mark_node)
 	{
+	  /* If this type is passed by invisible reference, make the PARM_DECL
+	     reflect that so that alias analysis knows that the actual object
+	     is external to the function.  */
+	  if (TREE_ADDRESSABLE (type))
+	    decl = build_decl (PARM_DECL, DECL_NAME (decl),
+			       build_reference_type (type));
+
 	  /* Top-level qualifiers on the parameters are
 	     ignored for function types.  */
 	  type = cp_build_qualified_type (type, 0);
@@ -8258,7 +8265,7 @@ grokparms (cp_parameter_declarator *first_parm, tree *parms)
 	    }
 
 	  if (!any_error && init)
-	    init = check_default_argument (decl, init);
+	    init = check_default_argument (type, init);
 	  else
 	    init = NULL_TREE;
 	}

gcc/testsuite/g++.dg/init/call1.C

+// Bug c++/16115
+// { dg-do run }
+
+extern "C" void abort(); 
+ 
+int count = 0; 
+ 
+struct T { 
+    T() { count++; } 
+    T(const T&) { count++; } 
+    ~T() { if (count==0) abort(); --count; } 
+}; 
+ 
+struct auto_ptr { 
+    T* p; 
+ 
+    auto_ptr(T* __p) : p(__p) { } 
+    ~auto_ptr() { delete p; } 
+ 
+    T* release() { 
+      T* t = p; 
+      p = 0; 
+      return t; 
+    } 
+}; 
+ 
+void destroy (auto_ptr a) { 
+  delete a.release(); 
+} 
+ 
+ 
+int main () 
+{ 
+  destroy (new T); 
+}