call.c (implicit_conversion): Handle conversion from initializer-list to scalar.

	* call.c (implicit_conversion): Handle conversion from
	initializer-list to scalar.
	(convert_like_real): Likewise.  Avoid crashing on list
	initialization with bad conversions.
	(can_convert): Use LOOKUP_EXPLICIT.
	(can_convert_arg_bad): Add flags parm.
	* cp-tree.h: Adjust.
	* typeck.c (convert_for_assignment): Pass flags.

From-SVN: r147933

4 files changed, 53 insertions, 8 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index bd057f0..9efd93e 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,14 @@
+2009-05-27  Jason Merrill  <jason@redhat.com>
+
+	* call.c (implicit_conversion): Handle conversion from
+	initializer-list to scalar.
+	(convert_like_real): Likewise.  Avoid crashing on list
+	initialization with bad conversions.
+	(can_convert): Use LOOKUP_EXPLICIT.
+	(can_convert_arg_bad): Add flags parm.
+	* cp-tree.h: Adjust.
+	* typeck.c (convert_for_assignment): Pass flags.
+
 2009-05-27  Ian Lance Taylor  <iant@google.com>
 
 	* Make-lang.in (g++$(exeext)): Change $(COMPILER) to $(LINKER).
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index a9c0367..138abe0 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -1400,9 +1400,31 @@ implicit_conversion (tree to, tree from, tree expr, bool c_cast_p,
   if (conv)
     return conv;
 
-  if (is_std_init_list (to) && expr
-      && BRACE_ENCLOSED_INITIALIZER_P (expr))
-    return build_list_conv (to, expr, flags);
+  if (expr && BRACE_ENCLOSED_INITIALIZER_P (expr))
+    {
+      if (is_std_init_list (to))
+	return build_list_conv (to, expr, flags);
+
+      /* Allow conversion from an initializer-list with one element to a
+	 scalar type if this is copy-initialization.  Direct-initialization
+	 would be something like int i({1}), which is invalid.  */
+      if (SCALAR_TYPE_P (to) && CONSTRUCTOR_NELTS (expr) <= 1
+	  && (flags & LOOKUP_ONLYCONVERTING))
+	{
+	  tree elt;
+	  if (CONSTRUCTOR_NELTS (expr) == 1)
+	    elt = CONSTRUCTOR_ELT (expr, 0)->value;
+	  else
+	    elt = integer_zero_node;
+	  conv = implicit_conversion (to, TREE_TYPE (elt), elt,
+				      c_cast_p, flags);
+	  if (conv)
+	    {
+	      conv->check_narrowing = true;
+	      return conv;
+	    }
+	}
+    }
 
   if (expr != NULL_TREE
       && (MAYBE_CLASS_TYPE_P (from)
@@ -4669,6 +4691,7 @@ convert_like_real (conversion *convs, tree expr, tree fn, int argnum,
 
   if (convs->bad_p
       && convs->kind != ck_user
+      && convs->kind != ck_list
       && convs->kind != ck_ambig
       && convs->kind != ck_ref_bind
       && convs->kind != ck_rvalue
@@ -4748,6 +4771,17 @@ convert_like_real (conversion *convs, tree expr, tree fn, int argnum,
 	return expr;
       }
     case ck_identity:
+      if (BRACE_ENCLOSED_INITIALIZER_P (expr))
+	{
+	  int nelts = CONSTRUCTOR_NELTS (expr);
+	  if (nelts == 0)
+	    expr = integer_zero_node;
+	  else if (nelts == 1)
+	    expr = CONSTRUCTOR_ELT (expr, 0)->value;
+	  else
+	    gcc_unreachable ();
+	}
+
       if (type_unknown_p (expr))
 	expr = instantiate_type (totype, expr, complain);
       /* Convert a constant to its underlying value, unless we are
@@ -7185,7 +7219,7 @@ tourney (struct z_candidate *candidates)
 bool
 can_convert (tree to, tree from)
 {
-  return can_convert_arg (to, from, NULL_TREE, LOOKUP_NORMAL);
+  return can_convert_arg (to, from, NULL_TREE, LOOKUP_IMPLICIT);
 }
 
 /* Returns nonzero if ARG (of type FROM) can be converted to TO.  */
@@ -7213,7 +7247,7 @@ can_convert_arg (tree to, tree from, tree arg, int flags)
 /* Like can_convert_arg, but allows dubious conversions as well.  */
 
 bool
-can_convert_arg_bad (tree to, tree from, tree arg)
+can_convert_arg_bad (tree to, tree from, tree arg, int flags)
 {
   conversion *t;
   void *p;
@@ -7222,7 +7256,7 @@ can_convert_arg_bad (tree to, tree from, tree arg)
   p = conversion_obstack_alloc (0);
   /* Try to perform the conversion.  */
   t  = implicit_conversion (to, from, arg, /*c_cast_p=*/false,
-			    LOOKUP_NORMAL);
+			    flags);
   /* Free all the conversions we allocated.  */
   obstack_free (&conversion_obstack, p);
 
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 79bc928..e473695 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -4191,7 +4191,7 @@ extern tree build_op_call			(tree, VEC(tree,gc) **,
 extern tree build_op_delete_call		(enum tree_code, tree, tree, bool, tree, tree);
 extern bool can_convert				(tree, tree);
 extern bool can_convert_arg			(tree, tree, tree, int);
-extern bool can_convert_arg_bad			(tree, tree, tree);
+extern bool can_convert_arg_bad			(tree, tree, tree, int);
 extern bool enforce_access			(tree, tree, tree);
 extern tree convert_default_arg			(tree, tree, tree, int);
 extern tree convert_arg_to_ellipsis		(tree);
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index d7fddb1..29ae831 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -6702,7 +6702,7 @@ convert_for_assignment (tree type, tree rhs,
      We allow bad conversions here because by the time we get to this point
      we are committed to doing the conversion.  If we end up doing a bad
      conversion, convert_like will complain.  */
-  if (!can_convert_arg_bad (type, rhstype, rhs))
+  if (!can_convert_arg_bad (type, rhstype, rhs, flags))
     {
       /* When -Wno-pmf-conversions is use, we just silently allow
 	 conversions from pointers-to-members to plain pointers.  If