Re: [C++ PATCH] Fix all rvalue references PRs

["Doug Gregor" <doug dot gregor at gmail dot com>]

Idiot! I forgot to attach the patch... attached here:

  - Doug

On Nov 5, 2007 9:42 AM, Doug Gregor <doug.gregor@gmail.com> wrote:
> This patch fixes the three outstanding PRs against the rvalue
> references implementation in the C++0x mode. It's really three trivial
> patches rolled into one.
>
> 33996: This is a case where merge_types was failing to preserve rvalue
> references. The fix is to use cp_build_reference_type, not
> build_reference_type.
> 33235: This is a case where having a trivial constructor was causing
> us to elide a move constructor. The fix is to not elide move
> constructors in move_over_call.
> 33930: This is a case where we were having trouble overloading between
> a const lvalue reference and a (non-const) rvalue reference. Turns out
> that compare_ics just needed to properly fall through to the
> lvalue-vs-rvalue comparison if the cv-qualification comparison of an
> ICS didn't give us an answer.
>
> Paolo, could you try this patch against some of the library work
> you've been doing? I know some of these test cases are distilled from
> examples from the C++0x library.
>
> Tested i686-pc-linux-gnu. Okay for mainline?
>
>   - Doug
>
> 2007-11-05  Douglas Gregor  <doug.gregor@gmail.com>
>
>         PR c++/33996
>         PR c++/33235
>         PR c++/33930
>         * typeck.c (merge_types): Don't lose rvalue references when
>         merging types.
>         * call.c (build_over_call): Don't elide move constructors just
>         because the copy constructor is trivial (!).
>         (compare_ics): If comparing cv-qualifiers fails, we can still order
>         based on binding lvalues vs. rvalues.
>
> 2007-11-05  Douglas Gregor  <doug.gregor@gmail.com>
>
>         PR c++/33996
>         PR c++/33235
>         PR c++/33930
>         * g++.dg/cpp0x/pr33996.C: New
>         * g++.dg/cpp0x/rv-trivial-bug.C: New
>         * g++.dg/cpp0x/pr33930.C: New
>

Index: testsuite/g++.dg/cpp0x/pr33996.C
===================================================================
--- testsuite/g++.dg/cpp0x/pr33996.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/pr33996.C	(revision 0)
@@ -0,0 +1,52 @@
+// { dg-options "-std=c++0x" }
+
+#define BUG
+struct type
+{
+  type() { }
+  type(const type&) { }
+
+private:
+  type(type&&);
+};
+
+template<typename _Tp>
+  struct identity
+  {
+    typedef _Tp type;
+  };
+
+template<typename _Tp>
+  inline _Tp&&
+  forward(typename identity<_Tp>::type&& __t)
+  { return __t; }
+
+struct vec
+{
+  template<typename _Args>
+    void
+    bar(_Args&& __args)
+#ifdef BUG
+    ;
+#else
+    {
+      type(forward<_Args>(__args));
+    }
+#endif
+};
+
+#ifdef BUG
+template<typename _Args>
+  void
+  vec::bar(_Args&& __args)
+  {
+    type(forward<_Args>(__args));
+  }
+#endif
+
+int main()
+{
+  vec v;
+  type c;
+  v.bar(c);
+}
Index: testsuite/g++.dg/cpp0x/rv-trivial-bug.C
===================================================================
--- testsuite/g++.dg/cpp0x/rv-trivial-bug.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/rv-trivial-bug.C	(revision 0)
@@ -0,0 +1,33 @@
+// { dg-do "run" }
+// { dg-options "-std=c++0x" }
+// PR c++/33235
+#include <cassert>
+
+int move_construct = 0;
+int move_assign = 0;
+
+struct base2
+{
+    base2() {}
+    base2(base2&&) {++move_construct;}
+    base2& operator=(base2&&) {++move_assign; return *this;}
+};
+
+int test2()
+{
+    base2 b;
+    base2 b2(b);
+    assert(move_construct == 0);
+    base2 b3(static_cast<base2&&>(b));
+    assert(move_construct == 1);
+    b = b2;
+    assert(move_assign == 0);
+    b = static_cast<base2&&>(b2);
+    assert(move_assign == 1);
+}
+
+int main()
+{
+    test2();
+    return 0;
+}
Index: testsuite/g++.dg/cpp0x/pr33930.C
===================================================================
--- testsuite/g++.dg/cpp0x/pr33930.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/pr33930.C	(revision 0)
@@ -0,0 +1,10 @@
+// { dg-options "-std=c++0x" }
+typedef const int* type;
+
+float& foo( const type& ggg );
+int& foo( type&& ggg );
+
+void bar( int* someptr )
+{
+  int& x = foo( someptr );
+}
Index: cp/typeck.c
===================================================================
--- cp/typeck.c	(revision 129899)
+++ cp/typeck.c	(working copy)
@@ -620,7 +620,7 @@ merge_types (tree t1, tree t2)
 	if (code1 == POINTER_TYPE)
 	  t1 = build_pointer_type (target);
 	else
-	  t1 = build_reference_type (target);
+	  t1 = cp_build_reference_type (target, TYPE_REF_IS_RVALUE (t1));
 	t1 = build_type_attribute_variant (t1, attributes);
 	t1 = cp_build_qualified_type (t1, quals);
 
Index: cp/call.c
===================================================================
--- cp/call.c	(revision 129899)
+++ cp/call.c	(working copy)
@@ -5076,7 +5076,8 @@ build_over_call (struct z_candidate *can
 	    return build_target_expr_with_type (arg, DECL_CONTEXT (fn));
 	}
       else if (TREE_CODE (arg) == TARGET_EXPR
-	       || TYPE_HAS_TRIVIAL_INIT_REF (DECL_CONTEXT (fn)))
+	       || (TYPE_HAS_TRIVIAL_INIT_REF (DECL_CONTEXT (fn))
+		   && !move_fn_p (fn)))
 	{
 	  tree to = stabilize_reference
 	    (build_indirect_ref (TREE_VALUE (args), 0));
@@ -6118,7 +6119,11 @@ compare_ics (conversion *ics1, conversio
   if (ics1->kind == ck_qual
       && ics2->kind == ck_qual
       && same_type_p (from_type1, from_type2))
-    return comp_cv_qual_signature (to_type1, to_type2);
+    {
+      int result = comp_cv_qual_signature (to_type1, to_type2);
+      if (result != 0)
+	return result;
+    }
 
   /* [over.ics.rank]