re PR c++/11867 (static_cast ignores ambiguity)

	PR c++/11687
	* call.c (standard_conversion): Improve comments.
	(perform_direct_initialization): Make sure we return an expression
	of the correct type.
	* typeck.c (build_static_cast): Check for ambiguity and
	accessibility when performing conversions.

	PR c++/11687
	* g++.dg/expr/static_cast5.C: New test.

From-SVN: r71157

5 files changed, 64 insertions, 20 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 755168e..1c8fef0 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,12 @@
+2003-09-06  Mark Mitchell  <mark@codesourcery.com>
+
+	PR c++/11687
+	* call.c (standard_conversion): Improve comments.
+	(perform_direct_initialization): Make sure we return an expression
+	of the correct type.
+	* typeck.c (build_static_cast): Check for ambiguity and
+	accessibility when performing conversions.
+
 2003-09-06  Gabriel Dos Reis  <gdr@integrable-solutions.net>
 
 	* cp-tree.h (add_binding): Remove declaration.
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index cc03adc..bc7e3b8 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -701,16 +701,25 @@ standard_conversion (tree to, tree from, tree expr)
 	    }
 	}
       else if (IS_AGGR_TYPE (TREE_TYPE (from))
-	       && IS_AGGR_TYPE (TREE_TYPE (to)))
+	       && IS_AGGR_TYPE (TREE_TYPE (to))
+	       /* [conv.ptr]
+		  
+	          An rvalue of type "pointer to cv D," where D is a
+		  class type, can be converted to an rvalue of type
+		  "pointer to cv B," where B is a base class (clause
+		  _class.derived_) of D.  If B is an inaccessible
+		  (clause _class.access_) or ambiguous
+		  (_class.member.lookup_) base class of D, a program
+		  that necessitates this conversion is ill-formed.  */
+	       /* Therefore, we use DERIVED_FROM_P, and not
+		  ACESSIBLY_UNIQUELY_DERIVED_FROM_P, in this test.  */
+	       && DERIVED_FROM_P (TREE_TYPE (to), TREE_TYPE (from)))
 	{
-	  if (DERIVED_FROM_P (TREE_TYPE (to), TREE_TYPE (from)))
-	    {
-	      from = 
-		cp_build_qualified_type (TREE_TYPE (to),
-					 cp_type_quals (TREE_TYPE (from)));
-	      from = build_pointer_type (from);
-	      conv = build_conv (PTR_CONV, from, conv);
-	    }
+	  from = 
+	    cp_build_qualified_type (TREE_TYPE (to),
+				     cp_type_quals (TREE_TYPE (from)));
+	  from = build_pointer_type (from);
+	  conv = build_conv (PTR_CONV, from, conv);
 	}
 
       if (tcode == POINTER_TYPE)
@@ -5970,10 +5979,13 @@ perform_direct_initialization_if_possible (tree type, tree expr)
      the overload resolution is ambiguous, the initialization is
      ill-formed.  */
   if (CLASS_TYPE_P (type))
-    return build_special_member_call (NULL_TREE, complete_ctor_identifier,
-				      build_tree_list (NULL_TREE, expr),
-				      TYPE_BINFO (type),
-				      LOOKUP_NORMAL);
+    {
+      expr = build_special_member_call (NULL_TREE, complete_ctor_identifier,
+					build_tree_list (NULL_TREE, expr),
+					TYPE_BINFO (type),
+					LOOKUP_NORMAL);
+      return build_cplus_new (type, expr);
+    }
   conv = implicit_conversion (type, TREE_TYPE (expr), expr,
 			      LOOKUP_NORMAL);
   if (!conv || ICS_BAD_FLAG (conv))
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index da07fea..8b391b8 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -4427,12 +4427,13 @@ build_static_cast (tree type, tree expr)
 					  (TREE_TYPE (type))))
       && at_least_as_qualified_p (TREE_TYPE (type), intype))
     {
-      /* At this point we have checked all of the conditions except
-	 that B is not a virtual base class of D.  That will be
-	 checked by build_base_path.  */
-      tree base = lookup_base (TREE_TYPE (type), intype, ba_any, NULL);
+      /* There is a standard conversion from "D*" to "B*" even if "B"
+	 is ambiguous or inaccessible.  Therefore, we ask lookup_base
+	 to check these conditions.  */
+      tree base = lookup_base (TREE_TYPE (type), intype, ba_check, NULL);
 
-      /* Convert from B* to D*.  */
+      /* Convert from "B*" to "D*".  This function will check that "B"
+	 is not a virtual base of "D".  */
       expr = build_base_path (MINUS_EXPR, build_address (expr), 
 			      base, /*nonnull=*/false);
       /* Convert the pointer to a reference -- but then remember that
@@ -4491,8 +4492,8 @@ build_static_cast (tree type, tree expr)
       tree base;
 
       check_for_casting_away_constness (intype, type, "static_cast");
-      base = lookup_base (TREE_TYPE (type), TREE_TYPE (intype), 
-			  ba_check | ba_quiet, NULL);
+      base = lookup_base (TREE_TYPE (type), TREE_TYPE (intype), ba_check, 
+			  NULL);
       return build_base_path (MINUS_EXPR, expr, base, /*nonnull=*/false);
     }
   
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 331c00d..d5b929a 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2003-09-06  Mark Mitchell  <mark@codesourcery.com>
+
+	PR c++/11687
+	* g++.dg/expr/static_cast5.C: New test.
+
 2003-09-06  Nathan Sidwell  <nathan@codesourcery.com>
 
 	PR c++/11794
diff --git a/gcc/testsuite/g++.dg/expr/static_cast5.C b/gcc/testsuite/g++.dg/expr/static_cast5.C
new file mode 100644
index 0000000..1a51f15
--- /dev/null
+++ b/gcc/testsuite/g++.dg/expr/static_cast5.C
@@ -0,0 +1,17 @@
+void ambig()
+{
+  struct A {};
+  struct B : A {};
+  struct C : A {};
+  struct D : B, C {};
+
+  D d;
+  A* ap = static_cast<B*> (&d);
+  D* db = static_cast<D*> (ap); // { dg-error "" }
+  
+  D& dr1 = static_cast<D&> (*ap); // { dg-error "" }
+  
+  A& ar = static_cast<C&> (d);
+  D& dr = static_cast<D&> (ar);  // { dg-error "" }
+}
+