call.c (conditional_conversion): Don't build BASE_CONVs for conversions between things that have the same type.

* call.c (conditional_conversion): Don't build BASE_CONVs for
	conversions between things that have the same type.
	(build_conditional_expr): Tweak.
	(convert_like): Some BASE_CONVs really do require the generation
	of code.

	* init.c (perform_member_init): Don't go through build_modify_expr
	for simple initializations.

From-SVN: r28310

gcc/cp/ChangeLog

@@ -1,3 +1,14 @@
+1999-07-28  Mark Mitchell  <mark@codesourcery.com>
+
+	* call.c (conditional_conversion): Don't build BASE_CONVs for
+	conversions between things that have the same type.
+	(build_conditional_expr): Tweak.
+	(convert_like): Some BASE_CONVs really do require the generation
+	of code.
+	
+	* init.c (perform_member_init): Don't go through build_modify_expr
+	for simple initializations.
+
 1999-07-27  Jason Merrill  <jason@yorick.cygnus.com>
 
 	* cp-tree.h (DECL_VIRTUAL_CONTEXT): New macro.

gcc/cp/call.c

@@ -2716,7 +2716,9 @@ conditional_conversion (e1, e2)
       if (at_least_as_qualified_p (t2, t1))
 	{
 	  conv = build1 (IDENTITY_CONV, t1, e1);
-	  conv = build_conv (BASE_CONV, t2, conv);
+	  if (!same_type_p (TYPE_MAIN_VARIANT (t1), 
+			    TYPE_MAIN_VARIANT (t2)))
+	    conv = build_conv (BASE_CONV, t2, conv);
 	  return conv;
 	}
       else
@@ -2865,11 +2867,22 @@ build_conditional_expr (arg1, arg2, arg3)
       else if (conv2 && !ICS_BAD_FLAG (conv2))
 	{
 	  arg2 = convert_like (conv2, arg2);
+	  /* That may not quite have done the trick.  If the two types
+	     are cv-qualified variants of one another, we will have
+	     just used an IDENTITY_CONV.  (There's no conversion from
+	     an lvalue of one class type to an lvalue of another type,
+	     even a cv-qualified variant, and we don't want to lose
+	     lvalue-ness here.)  So, we manually add a NOP_EXPR here
+	     if necessary.  */
+	  if (!same_type_p (TREE_TYPE (arg2), arg3_type))
+	    arg2 = build1 (NOP_EXPR, arg3_type, arg2);
 	  arg2_type = TREE_TYPE (arg2);
 	}
       else if (conv3 && !ICS_BAD_FLAG (conv3))
 	{
 	  arg3 = convert_like (conv3, arg3);
+	  if (!same_type_p (TREE_TYPE (arg3), arg2_type))
+	    arg2 = build1 (NOP_EXPR, arg2_type, arg3);
 	  arg3_type = TREE_TYPE (arg3);
 	}
     }
@@ -3647,12 +3660,19 @@ convert_like (convs, expr)
 	return expr;
       /* else fall through */
     case BASE_CONV:
-      if (TREE_CODE (convs) == BASE_CONV
-	  && !NEED_TEMPORARY_P (convs))
-	/* We are going to bind a reference directly to a base-class
-	   subobject of EXPR.  We don't have to generate any code
-	   here.  */
-	return expr;
+      if (TREE_CODE (convs) == BASE_CONV && !NEED_TEMPORARY_P (convs))
+	{
+	  /* We are going to bind a reference directly to a base-class
+	     subobject of EXPR.  */
+	  tree base_ptr = build_pointer_type (TREE_TYPE (convs));
+
+	  /* Build an expression for `*((base*) &expr)'.  */
+	  expr = build_unary_op (ADDR_EXPR, expr, 0);
+	  expr = perform_implicit_conversion (base_ptr, expr);
+	  expr = build_indirect_ref (expr, "implicit conversion");
+	  return expr;
+	}
+
       {
 	tree cvt_expr = build_user_type_conversion
 	  (TREE_TYPE (convs), expr, LOOKUP_NORMAL);

gcc/cp/init.c

@@ -194,13 +194,21 @@ perform_member_init (member, name, init, explicit)
 	    {
 	      /* default-initialization.  */
 	      if (AGGREGATE_TYPE_P (type))
-		init = build (CONSTRUCTOR, type, NULL_TREE, NULL_TREE);
- 	      else if (TREE_CODE (type) == REFERENCE_TYPE)
 		{
-		  cp_error ("default-initialization of `%#D', which has reference type",
-			    member);
-		  init = error_mark_node;
+		  /* This is a default initialization of an aggregate,
+		     but not one of non-POD class type.  We cleverly
+		     notice that the initialization rules in such a
+		     case are the same as for initialization with an
+		     empty brace-initialization list.  We don't want
+		     to call build_modify_expr as that will go looking
+		     for constructors and such.  */
+		  tree e = build (CONSTRUCTOR, type, NULL_TREE, NULL_TREE);
+		  TREE_SIDE_EFFECTS (e) = 1;
+		  expand_expr_stmt (build (INIT_EXPR, type, decl, e));
 		}
+ 	      else if (TREE_CODE (type) == REFERENCE_TYPE)
+		cp_error ("default-initialization of `%#D', which has reference type",
+			  member);
 	      else
 		init = integer_zero_node;
 	    }
@@ -221,12 +229,8 @@ perform_member_init (member, name, init, explicit)
 	    init = TREE_VALUE (init);
 	}
 
-      /* We only build this with a null init if we got it from the
-	 current_member_init_list.  */
-      if (init || explicit)
-	{
-	  expand_expr_stmt (build_modify_expr (decl, INIT_EXPR, init));
-	}
+      if (init)
+	expand_expr_stmt (build_modify_expr (decl, INIT_EXPR, init));
     }
 
   expand_end_target_temps ();

gcc/testsuite/g++.old-deja/g++.other/cond2.C

@@ -0,0 +1,11 @@
+// Build don't link:
+// Origin: Loring Holden <lsh@cs.brown.edu>
+
+class Wpt {};
+
+class RAYhit {
+   protected:
+      Wpt       _nearpt;
+   public:
+      Wpt       surf        () const { return true ? Wpt(): _nearpt; } 
+};

gcc/testsuite/g++.old-deja/g++.other/init14.C

@@ -0,0 +1,22 @@
+// Build don't link:
+// Origin: bkoz@nabi.net
+
+typedef struct
+{
+  int count;
+} mbstate_t;
+
+struct fpos
+{
+  mbstate_t  _M_st;
+  fpos(int __pos)
+    : _M_st() { 
+  }
+};
+
+int main ()
+{
+  fpos f (2);
+}
+
+

gcc/testsuite/g++.old-deja/g++.other/ref3.C

@@ -0,0 +1,30 @@
+// Origin: Mark Mitchell <mark@codesourcery.com>
+
+struct B1
+{
+  int i;
+};
+
+struct B2
+{
+  int j;
+};
+
+struct D: public B1, B2 
+{
+};
+
+bool f (B2& b)
+{
+  return b.j == 7;
+}
+
+int main ()
+{
+  D d;
+  d.i = 2;
+  d.j = 7;
+  if (!f (d))
+    return 1;
+}
+