Exemple #1
0
static tree
check_noexcept_r (tree *tp, int * /*walk_subtrees*/, void * /*data*/)
{
  tree t = *tp;
  enum tree_code code = TREE_CODE (t);
  if ((code == CALL_EXPR && CALL_EXPR_FN (t))
      || code == AGGR_INIT_EXPR)
    {
      /* We can only use the exception specification of the called function
	 for determining the value of a noexcept expression; we can't use
	 TREE_NOTHROW, as it might have a different value in another
	 translation unit, creating ODR problems.

         We could use TREE_NOTHROW (t) for !TREE_PUBLIC fns, though... */
      tree fn = (code == AGGR_INIT_EXPR
		 ? AGGR_INIT_EXPR_FN (t) : CALL_EXPR_FN (t));
      tree type = TREE_TYPE (fn);
      gcc_assert (POINTER_TYPE_P (type));
      type = TREE_TYPE (type);

      STRIP_NOPS (fn);
      if (TREE_CODE (fn) == ADDR_EXPR)
	fn = TREE_OPERAND (fn, 0);
      if (TREE_CODE (fn) == FUNCTION_DECL)
	{
	  /* We do use TREE_NOTHROW for ABI internals like __dynamic_cast,
	     and for C library functions known not to throw.  */
	  if (DECL_EXTERN_C_P (fn)
	      && (DECL_ARTIFICIAL (fn)
		  || nothrow_libfn_p (fn)))
	    return TREE_NOTHROW (fn) ? NULL_TREE : fn;
	  /* A call to a constexpr function is noexcept if the call
	     is a constant expression.  */
	  if (DECL_DECLARED_CONSTEXPR_P (fn)
	      && is_sub_constant_expr (t))
	    return NULL_TREE;
	}
      if (!TYPE_NOTHROW_P (type))
	return fn;
    }

  return NULL_TREE;
}
Exemple #2
0
tree
convert_to_void (tree expr, const char *implicit, tsubst_flags_t complain)
{
  if (expr == error_mark_node
      || TREE_TYPE (expr) == error_mark_node)
    return error_mark_node;
  if (!TREE_TYPE (expr))
    return expr;
  if (invalid_nonstatic_memfn_p (expr, complain))
    return error_mark_node;
  if (TREE_CODE (expr) == PSEUDO_DTOR_EXPR)
    {
      if (complain & tf_error)
        error ("pseudo-destructor is not called");
      return error_mark_node;
    }
  if (VOID_TYPE_P (TREE_TYPE (expr)))
    return expr;
  switch (TREE_CODE (expr))
    {
    case COND_EXPR:
      {
	/* The two parts of a cond expr might be separate lvalues.  */
	tree op1 = TREE_OPERAND (expr,1);
	tree op2 = TREE_OPERAND (expr,2);
	tree new_op1 = convert_to_void
	  (op1, (implicit && !TREE_SIDE_EFFECTS (op2)
		 ? "second operand of conditional" : NULL), complain);
	tree new_op2 = convert_to_void
	  (op2, (implicit && !TREE_SIDE_EFFECTS (op1)
		 ? "third operand of conditional" : NULL), complain);

	expr = build3 (COND_EXPR, TREE_TYPE (new_op1),
		       TREE_OPERAND (expr, 0), new_op1, new_op2);
	break;
      }

    case COMPOUND_EXPR:
      {
	/* The second part of a compound expr contains the value.  */
	tree op1 = TREE_OPERAND (expr,1);
	tree new_op1 = convert_to_void
	  (op1, (implicit && !TREE_NO_WARNING (expr)
		 ? "right-hand operand of comma" : NULL), complain);

	if (new_op1 != op1)
	  {
	    tree t = build2 (COMPOUND_EXPR, TREE_TYPE (new_op1),
			     TREE_OPERAND (expr, 0), new_op1);
	    expr = t;
	  }

	break;
      }

    case NON_LVALUE_EXPR:
    case NOP_EXPR:
      /* These have already decayed to rvalue.  */
      break;

    case CALL_EXPR:   /* We have a special meaning for volatile void fn().  */
      break;

    case INDIRECT_REF:
      {
	tree type = TREE_TYPE (expr);
	int is_reference = TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0)))
			   == REFERENCE_TYPE;
	int is_volatile = TYPE_VOLATILE (type);
	int is_complete = COMPLETE_TYPE_P (complete_type (type));

	/* Can't load the value if we don't know the type.  */
	if (is_volatile && !is_complete)
          {
            if (complain & tf_warning)
              warning (0, "object of incomplete type %qT will not be accessed in %s",
                       type, implicit ? implicit : "void context");
          }
	/* Don't load the value if this is an implicit dereference, or if
	   the type needs to be handled by ctors/dtors.  */
	else if (is_volatile && (is_reference || TREE_ADDRESSABLE (type)))
          {
            if (complain & tf_warning)
              warning (0, "object of type %qT will not be accessed in %s",
                       TREE_TYPE (TREE_OPERAND (expr, 0)),
                       implicit ? implicit : "void context");
          }
	if (is_reference || !is_volatile || !is_complete || TREE_ADDRESSABLE (type))
	  expr = TREE_OPERAND (expr, 0);

	break;
      }

    case VAR_DECL:
      {
	/* External variables might be incomplete.  */
	tree type = TREE_TYPE (expr);
	int is_complete = COMPLETE_TYPE_P (complete_type (type));

	if (TYPE_VOLATILE (type) && !is_complete && (complain & tf_warning))
	  warning (0, "object %qE of incomplete type %qT will not be accessed in %s",
		   expr, type, implicit ? implicit : "void context");
	break;
      }

    case TARGET_EXPR:
      /* Don't bother with the temporary object returned from a function if
	 we don't use it and don't need to destroy it.  We'll still
	 allocate space for it in expand_call or declare_return_variable,
	 but we don't need to track it through all the tree phases.  */
      if (TARGET_EXPR_IMPLICIT_P (expr)
	  && TYPE_HAS_TRIVIAL_DESTRUCTOR (TREE_TYPE (expr)))
	{
	  tree init = TARGET_EXPR_INITIAL (expr);
	  if (TREE_CODE (init) == AGGR_INIT_EXPR
	      && !AGGR_INIT_VIA_CTOR_P (init))
	    {
	      tree fn = AGGR_INIT_EXPR_FN (init);
	      expr = build_call_array (TREE_TYPE (TREE_TYPE (TREE_TYPE (fn))),
				       fn,
				       aggr_init_expr_nargs (init),
				       AGGR_INIT_EXPR_ARGP (init));
	    }
	}
      break;

    default:;
    }
  {
    tree probe = expr;

    if (TREE_CODE (probe) == ADDR_EXPR)
      probe = TREE_OPERAND (expr, 0);
    if (type_unknown_p (probe))
      {
	/* [over.over] enumerates the places where we can take the address
	   of an overloaded function, and this is not one of them.  */
	if (complain & tf_error)
	  error ("%s cannot resolve address of overloaded function",
		 implicit ? implicit : "void cast");
	else
	  return error_mark_node;
	expr = void_zero_node;
      }
    else if (implicit && probe == expr && is_overloaded_fn (probe))
      {
	/* Only warn when there is no &.  */
	if (complain & tf_warning)
	  warning (OPT_Waddress, "%s is a reference, not call, to function %qE",
		   implicit, expr);
	if (TREE_CODE (expr) == COMPONENT_REF)
	  expr = TREE_OPERAND (expr, 0);
      }
  }

  if (expr != error_mark_node && !VOID_TYPE_P (TREE_TYPE (expr)))
    {
      if (implicit
	  && warn_unused_value
	  && !TREE_NO_WARNING (expr)
	  && !processing_template_decl)
	{
	  /* The middle end does not warn about expressions that have
	     been explicitly cast to void, so we must do so here.  */
	  if (!TREE_SIDE_EFFECTS (expr)) {
            if (complain & tf_warning)
              warning (OPT_Wunused_value, "%s has no effect", implicit);
          }
	  else
	    {
	      tree e;
	      enum tree_code code;
	      enum tree_code_class tclass;

	      e = expr;
	      /* We might like to warn about (say) "(int) f()", as the
		 cast has no effect, but the compiler itself will
		 generate implicit conversions under some
		 circumstances.  (For example a block copy will be
		 turned into a call to "__builtin_memcpy", with a
		 conversion of the return value to an appropriate
		 type.)  So, to avoid false positives, we strip
		 conversions.  Do not use STRIP_NOPs because it will
		 not strip conversions to "void", as that is not a
		 mode-preserving conversion.  */
	      while (TREE_CODE (e) == NOP_EXPR)
		e = TREE_OPERAND (e, 0);

	      code = TREE_CODE (e);
	      tclass = TREE_CODE_CLASS (code);
	      if ((tclass == tcc_comparison
		   || tclass == tcc_unary
		   || (tclass == tcc_binary
		       && !(code == MODIFY_EXPR
			    || code == INIT_EXPR
			    || code == PREDECREMENT_EXPR
			    || code == PREINCREMENT_EXPR
			    || code == POSTDECREMENT_EXPR
			    || code == POSTINCREMENT_EXPR)))
                  && (complain & tf_warning))
		warning (OPT_Wunused_value, "value computed is not used");
	    }
	}
      expr = build1 (CONVERT_EXPR, void_type_node, expr);
    }
  if (! TREE_SIDE_EFFECTS (expr))
    expr = void_zero_node;
  return expr;
}
Exemple #3
0
bool
cp_dump_tree (void* dump_info, tree t)
{
  enum tree_code code;
  dump_info_p di = (dump_info_p) dump_info;

  /* Figure out what kind of node this is.  */
  code = TREE_CODE (t);

  if (DECL_P (t))
    {
      if (DECL_LANG_SPECIFIC (t) && DECL_LANGUAGE (t) != lang_cplusplus)
	dump_string_field (di, "lang", language_to_string (DECL_LANGUAGE (t)));
    }

  switch (code)
    {
    case IDENTIFIER_NODE:
      if (IDENTIFIER_OPNAME_P (t))
	{
	  dump_string_field (di, "note", "operator");
	  return true;
	}
      else if (IDENTIFIER_TYPENAME_P (t))
	{
	  dump_child ("tynm", TREE_TYPE (t));
	  return true;
	}
      break;

    case OFFSET_TYPE:
      dump_string_field (di, "note", "ptrmem");
      dump_child ("ptd", TYPE_PTRMEM_POINTED_TO_TYPE (t));
      dump_child ("cls", TYPE_PTRMEM_CLASS_TYPE (t));
      return true;

    case RECORD_TYPE:
      if (TYPE_PTRMEMFUNC_P (t))
	{
	  dump_string_field (di, "note", "ptrmem");
	  dump_child ("ptd", TYPE_PTRMEM_POINTED_TO_TYPE (t));
	  dump_child ("cls", TYPE_PTRMEM_CLASS_TYPE (t));
	  return true;
	}
      /* Fall through.  */

    case UNION_TYPE:
      /* Is it a type used as a base? */
      if (TYPE_CONTEXT (t) && TREE_CODE (TYPE_CONTEXT (t)) == TREE_CODE (t)
	  && CLASSTYPE_AS_BASE (TYPE_CONTEXT (t)) == t)
	{
	  dump_child ("bfld", TYPE_CONTEXT (t));
	  return true;
	}

      if (! MAYBE_CLASS_TYPE_P (t))
	break;

      dump_child ("vfld", TYPE_VFIELD (t));
      if (CLASSTYPE_TEMPLATE_SPECIALIZATION(t))
	dump_string(di, "spec");

      if (!dump_flag (di, TDF_SLIM, t) && TYPE_BINFO (t))
	{
	  int i;
	  tree binfo;
	  tree base_binfo;

	  for (binfo = TYPE_BINFO (t), i = 0;
	       BINFO_BASE_ITERATE (binfo, i, base_binfo); ++i)
	    {
	      dump_child ("base", BINFO_TYPE (base_binfo));
	      if (BINFO_VIRTUAL_P (base_binfo))
		dump_string_field (di, "spec", "virt");
	      dump_access (di, base_binfo);
	    }
	}
      break;

    case FIELD_DECL:
      dump_access (di, t);
      if (DECL_MUTABLE_P (t))
	dump_string_field (di, "spec", "mutable");
      break;

    case VAR_DECL:
      if (TREE_CODE (CP_DECL_CONTEXT (t)) == RECORD_TYPE)
	dump_access (di, t);
      if (TREE_STATIC (t) && !TREE_PUBLIC (t))
	dump_string_field (di, "link", "static");
      break;

    case FUNCTION_DECL:
      if (!DECL_THUNK_P (t))
	{
	  if (DECL_OVERLOADED_OPERATOR_P (t)) {
	    dump_string_field (di, "note", "operator");
	    dump_op (di, t);
	  }
	  if (DECL_FUNCTION_MEMBER_P (t))
	    {
	      dump_string_field (di, "note", "member");
	      dump_access (di, t);
	    }
	  if (DECL_PURE_VIRTUAL_P (t))
	    dump_string_field (di, "spec", "pure");
	  if (DECL_VIRTUAL_P (t))
	    dump_string_field (di, "spec", "virt");
	  if (DECL_CONSTRUCTOR_P (t))
	    dump_string_field (di, "note", "constructor");
	  if (DECL_DESTRUCTOR_P (t))
	    dump_string_field (di, "note", "destructor");
	  if (DECL_CONV_FN_P (t))
	    dump_string_field (di, "note", "conversion");
	  if (DECL_GLOBAL_CTOR_P (t))
	    dump_string_field (di, "note", "global init");
	  if (DECL_GLOBAL_DTOR_P (t))
	    dump_string_field (di, "note", "global fini");
	  if (DECL_FRIEND_PSEUDO_TEMPLATE_INSTANTIATION (t))
	    dump_string_field (di, "note", "pseudo tmpl");
	}
      else
	{
	  tree virt = THUNK_VIRTUAL_OFFSET (t);

	  dump_string_field (di, "note", "thunk");
	  if (DECL_THIS_THUNK_P (t))
	    dump_string_field (di, "note", "this adjusting");
	  else
	    {
	      dump_string_field (di, "note", "result adjusting");
	      if (virt)
		virt = BINFO_VPTR_FIELD (virt);
	    }
	  dump_int (di, "fixd", THUNK_FIXED_OFFSET (t));
	  if (virt)
	    dump_int (di, "virt", tree_to_shwi (virt));
	  dump_child ("fn", DECL_INITIAL (t));
	}
      break;

    case NAMESPACE_DECL:
      if (DECL_NAMESPACE_ALIAS (t))
	dump_child ("alis", DECL_NAMESPACE_ALIAS (t));
      else if (!dump_flag (di, TDF_SLIM, t))
	dump_child ("dcls", cp_namespace_decls (t));
      break;

    case TEMPLATE_DECL:
      dump_child ("rslt", DECL_TEMPLATE_RESULT (t));
      dump_child ("inst", DECL_TEMPLATE_INSTANTIATIONS (t));
      dump_child ("spcs", DECL_TEMPLATE_SPECIALIZATIONS (t));
      dump_child ("prms", DECL_TEMPLATE_PARMS (t));
      break;

    case OVERLOAD:
      dump_child ("crnt", OVL_CURRENT (t));
      dump_child ("chan", OVL_CHAIN (t));
      break;

    case TRY_BLOCK:
      dump_stmt (di, t);
      if (CLEANUP_P (t))
	dump_string_field (di, "note", "cleanup");
      dump_child ("body", TRY_STMTS (t));
      dump_child ("hdlr", TRY_HANDLERS (t));
      break;

    case EH_SPEC_BLOCK:
      dump_stmt (di, t);
      dump_child ("body", EH_SPEC_STMTS (t));
      dump_child ("raises", EH_SPEC_RAISES (t));
      break;

    case PTRMEM_CST:
      dump_child ("clas", PTRMEM_CST_CLASS (t));
      dump_child ("mbr", PTRMEM_CST_MEMBER (t));
      break;

    case THROW_EXPR:
      /* These nodes are unary, but do not have code class `1'.  */
      dump_child ("op 0", TREE_OPERAND (t, 0));
      break;

    case AGGR_INIT_EXPR:
      {
	int i = 0;
	tree arg;
	aggr_init_expr_arg_iterator iter;
	dump_int (di, "ctor", AGGR_INIT_VIA_CTOR_P (t));
	dump_child ("fn", AGGR_INIT_EXPR_FN (t));
	FOR_EACH_AGGR_INIT_EXPR_ARG (arg, iter, t)
	  {
	    char buffer[32];
	    sprintf (buffer, "%u", i);
	    dump_child (buffer, arg);
	    i++;
	  }
	dump_child ("decl", AGGR_INIT_EXPR_SLOT (t));
      }
      break;

    case HANDLER:
      dump_stmt (di, t);
      dump_child ("parm", HANDLER_PARMS (t));
      dump_child ("body", HANDLER_BODY (t));
      break;

    case MUST_NOT_THROW_EXPR:
      dump_stmt (di, t);
      dump_child ("body", TREE_OPERAND (t, 0));
      dump_child ("cond", MUST_NOT_THROW_COND (t));
      break;

    case USING_STMT:
      dump_stmt (di, t);
      dump_child ("nmsp", USING_STMT_NAMESPACE (t));
      break;

    case CLEANUP_STMT:
      dump_stmt (di, t);
      dump_child ("decl", CLEANUP_DECL (t));
      dump_child ("expr", CLEANUP_EXPR (t));
      dump_child ("body", CLEANUP_BODY (t));
      break;

    case IF_STMT:
      dump_stmt (di, t);
      dump_child ("cond", IF_COND (t));
      dump_child ("then", THEN_CLAUSE (t));
      dump_child ("else", ELSE_CLAUSE (t));
      break;

    case BREAK_STMT:
    case CONTINUE_STMT:
      dump_stmt (di, t);
      break;

    case DO_STMT:
      dump_stmt (di, t);
      dump_child ("body", DO_BODY (t));
      dump_child ("cond", DO_COND (t));
      break;

    case FOR_STMT:
      dump_stmt (di, t);
      dump_child ("init", FOR_INIT_STMT (t));
      dump_child ("cond", FOR_COND (t));
      dump_child ("expr", FOR_EXPR (t));
      dump_child ("body", FOR_BODY (t));
      break;

    case RANGE_FOR_STMT:
      dump_stmt (di, t);
      dump_child ("decl", RANGE_FOR_DECL (t));
      dump_child ("expr", RANGE_FOR_EXPR (t));
      dump_child ("body", RANGE_FOR_BODY (t));
      break;

    case SWITCH_STMT:
      dump_stmt (di, t);
      dump_child ("cond", SWITCH_STMT_COND (t));
      dump_child ("body", SWITCH_STMT_BODY (t));
      break;

    case WHILE_STMT:
      dump_stmt (di, t);
      dump_child ("cond", WHILE_COND (t));
      dump_child ("body", WHILE_BODY (t));
      break;

    case STMT_EXPR:
      dump_child ("stmt", STMT_EXPR_STMT (t));
      break;

    case EXPR_STMT:
      dump_stmt (di, t);
      dump_child ("expr", EXPR_STMT_EXPR (t));
      break;

    default:
      break;
    }
Exemple #4
0
tree
convert_to_void (tree expr, impl_conv_void implicit, tsubst_flags_t complain)
{
  if (expr == error_mark_node
      || TREE_TYPE (expr) == error_mark_node)
    return error_mark_node;

  if (implicit == ICV_CAST)
    mark_exp_read (expr);
  else
    {
      tree exprv = expr;

      while (TREE_CODE (exprv) == COMPOUND_EXPR)
	exprv = TREE_OPERAND (exprv, 1);
      if (DECL_P (exprv)
	  || handled_component_p (exprv)
	  || TREE_CODE (exprv) == INDIRECT_REF)
	/* Expr is not being 'used' here, otherwise we whould have
	   called mark_{rl}value_use use here, which would have in turn
	   called mark_exp_read.  Rather, we call mark_exp_read directly
	   to avoid some warnings when
	   -Wunused-but-set-{variable,parameter} is in effect.  */
	mark_exp_read (exprv);
    }

  if (!TREE_TYPE (expr))
    return expr;
  if (invalid_nonstatic_memfn_p (expr, complain))
    return error_mark_node;
  if (TREE_CODE (expr) == PSEUDO_DTOR_EXPR)
    {
      if (complain & tf_error)
        error ("pseudo-destructor is not called");
      return error_mark_node;
    }
  if (VOID_TYPE_P (TREE_TYPE (expr)))
    return expr;
  switch (TREE_CODE (expr))
    {
    case COND_EXPR:
      {
	/* The two parts of a cond expr might be separate lvalues.  */
	tree op1 = TREE_OPERAND (expr,1);
	tree op2 = TREE_OPERAND (expr,2);
	bool side_effects = TREE_SIDE_EFFECTS (op1) || TREE_SIDE_EFFECTS (op2);
	tree new_op1, new_op2;
	if (implicit != ICV_CAST && !side_effects)
	  {
	    new_op1 = convert_to_void (op1, ICV_SECOND_OF_COND, complain);
	    new_op2 = convert_to_void (op2, ICV_THIRD_OF_COND, complain);
	  }
	else
	  {
	    new_op1 = convert_to_void (op1, ICV_CAST, complain);
	    new_op2 = convert_to_void (op2, ICV_CAST, complain);
	  }

	expr = build3 (COND_EXPR, TREE_TYPE (new_op1),
		       TREE_OPERAND (expr, 0), new_op1, new_op2);
	break;
      }

    case COMPOUND_EXPR:
      {
	/* The second part of a compound expr contains the value.  */
	tree op1 = TREE_OPERAND (expr,1);
	tree new_op1;
	if (implicit != ICV_CAST && !TREE_NO_WARNING (expr))
	  new_op1 = convert_to_void (op1, ICV_RIGHT_OF_COMMA, complain);
	else
	  new_op1 = convert_to_void (op1, ICV_CAST, complain);

	if (new_op1 != op1)
	  {
	    tree t = build2 (COMPOUND_EXPR, TREE_TYPE (new_op1),
			     TREE_OPERAND (expr, 0), new_op1);
	    expr = t;
	  }

	break;
      }

    case NON_LVALUE_EXPR:
    case NOP_EXPR:
      /* These have already decayed to rvalue.  */
      break;

    case CALL_EXPR:   /* We have a special meaning for volatile void fn().  */
      break;

    case INDIRECT_REF:
      {
	tree type = TREE_TYPE (expr);
	int is_reference = TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0)))
			   == REFERENCE_TYPE;
	int is_volatile = TYPE_VOLATILE (type);
	int is_complete = COMPLETE_TYPE_P (complete_type (type));

	/* Can't load the value if we don't know the type.  */
	if (is_volatile && !is_complete)
          {
            if (complain & tf_warning)
	      switch (implicit)
		{
	      	  case ICV_CAST:
		    warning (0, "conversion to void will not access "
				"object of incomplete type %qT", type);
		    break;
		  case ICV_SECOND_OF_COND:
		    warning (0, "indirection will not access object of "
				"incomplete type %qT in second operand "
				"of conditional expression", type);
		    break;
		  case ICV_THIRD_OF_COND:
		    warning (0, "indirection will not access object of "
				"incomplete type %qT in third operand "
				"of conditional expression", type);
		    break;
		  case ICV_RIGHT_OF_COMMA:
		    warning (0, "indirection will not access object of "
				"incomplete type %qT in right operand of "
				"comma operator", type);
		    break;
		  case ICV_LEFT_OF_COMMA:
		    warning (0, "indirection will not access object of "
				"incomplete type %qT in left operand of "
				"comma operator", type);
		    break;
		  case ICV_STATEMENT:
		    warning (0, "indirection will not access object of "
				"incomplete type %qT in statement", type);
		     break;
		  case ICV_THIRD_IN_FOR:
		    warning (0, "indirection will not access object of "
				"incomplete type %qT in for increment "
				"expression", type);
		    break;
		  default:
		    gcc_unreachable ();
		}
          }
	/* Don't load the value if this is an implicit dereference, or if
	   the type needs to be handled by ctors/dtors.  */
	else if (is_volatile && is_reference)
          {
            if (complain & tf_warning)
	      switch (implicit)
		{
	      	  case ICV_CAST:
		    warning (0, "conversion to void will not access "
				"object of type %qT", type);
		    break;
		  case ICV_SECOND_OF_COND:
		    warning (0, "implicit dereference will not access object "
				"of type %qT in second operand of "
				"conditional expression", type);
		    break;
		  case ICV_THIRD_OF_COND:
		    warning (0, "implicit dereference will not access object "
		  	      	"of type %qT in third operand of "
				"conditional expression", type);
		    break;
		  case ICV_RIGHT_OF_COMMA:
		    warning (0, "implicit dereference will not access object "
		    		"of type %qT in right operand of "
				"comma operator", type);
		    break;
		  case ICV_LEFT_OF_COMMA:
		    warning (0, "implicit dereference will not access object "
		    		"of type %qT in left operand of comma operator",
			     type);
		    break;
		  case ICV_STATEMENT:
		    warning (0, "implicit dereference will not access object "
		     		"of type %qT in statement",  type);
		     break;
		  case ICV_THIRD_IN_FOR:
		    warning (0, "implicit dereference will not access object "
		    		"of type %qT in for increment expression",
			     type);
		    break;
		  default:
		    gcc_unreachable ();
		}
          }
	else if (is_volatile && TREE_ADDRESSABLE (type))
	  {
	    if (complain & tf_warning)
	      switch (implicit)
		{
	      	  case ICV_CAST:
		    warning (0, "conversion to void will not access "
				"object of non-trivially-copyable type %qT",
			     type);
		    break;
		  case ICV_SECOND_OF_COND:
		    warning (0, "indirection will not access object of "
				"non-trivially-copyable type %qT in second "
				"operand of conditional expression", type);
		    break;
		  case ICV_THIRD_OF_COND:
		    warning (0, "indirection will not access object of "
		  	      	"non-trivially-copyable type %qT in third "
				"operand of conditional expression", type);
		    break;
		  case ICV_RIGHT_OF_COMMA:
		    warning (0, "indirection will not access object of "
		    		"non-trivially-copyable type %qT in right "
				"operand of comma operator", type);
		    break;
		  case ICV_LEFT_OF_COMMA:
		    warning (0, "indirection will not access object of "
		    		"non-trivially-copyable type %qT in left "
				"operand of comma operator", type);
		    break;
		  case ICV_STATEMENT:
		    warning (0, "indirection will not access object of "
		     		"non-trivially-copyable type %qT in statement",
			      type);
		     break;
		  case ICV_THIRD_IN_FOR:
		    warning (0, "indirection will not access object of "
		    		"non-trivially-copyable type %qT in for "
				"increment expression", type);
		    break;
		  default:
		    gcc_unreachable ();
		}
	  }
	if (is_reference || !is_volatile || !is_complete || TREE_ADDRESSABLE (type))
          {
            /* Emit a warning (if enabled) when the "effect-less" INDIRECT_REF
               operation is stripped off. Note that we don't warn about
               - an expression with TREE_NO_WARNING set. (For an example of
                 such expressions, see build_over_call in call.c.)
               - automatic dereferencing of references, since the user cannot
                 control it. (See also warn_if_unused_value() in stmt.c.)  */
            if (warn_unused_value
		&& implicit != ICV_CAST
                && (complain & tf_warning)
                && !TREE_NO_WARNING (expr)
                && !is_reference)
              warning (OPT_Wunused_value, "value computed is not used");
            expr = TREE_OPERAND (expr, 0);
          }

	break;
      }

    case VAR_DECL:
      {
	/* External variables might be incomplete.  */
	tree type = TREE_TYPE (expr);
	int is_complete = COMPLETE_TYPE_P (complete_type (type));

	if (TYPE_VOLATILE (type) && !is_complete && (complain & tf_warning))
	  switch (implicit)
	    {
	      case ICV_CAST:
		warning (0, "conversion to void will not access "
			    "object %qE of incomplete type %qT", expr, type);
		break;
	      case ICV_SECOND_OF_COND:
	        warning (0, "variable %qE of incomplete type %qT will not "
			    "be accessed in second operand of "
			    "conditional expression", expr, type);
		break;
	      case ICV_THIRD_OF_COND:
	        warning (0, "variable %qE of incomplete type %qT will not "
			    "be accessed in third operand of "
			    "conditional expression", expr, type);
		break;
	      case ICV_RIGHT_OF_COMMA:
	        warning (0, "variable %qE of incomplete type %qT will not "
			    "be accessed in right operand of comma operator",
			 expr, type);
		break;
	      case ICV_LEFT_OF_COMMA:
	        warning (0, "variable %qE of incomplete type %qT will not "
			    "be accessed in left operand of comma operator",
			 expr, type);
		break;
	      case ICV_STATEMENT:
	        warning (0, "variable %qE of incomplete type %qT will not "
		            "be accessed in statement", expr, type);
		break;
	      case ICV_THIRD_IN_FOR:
	        warning (0, "variable %qE of incomplete type %qT will not "
			    "be accessed in for increment expression",
		         expr, type);
		break;
	      default:
	        gcc_unreachable ();
	    }

	break;
      }

    case TARGET_EXPR:
      /* Don't bother with the temporary object returned from a function if
	 we don't use it and don't need to destroy it.  We'll still
	 allocate space for it in expand_call or declare_return_variable,
	 but we don't need to track it through all the tree phases.  */
      if (TARGET_EXPR_IMPLICIT_P (expr)
	  && TYPE_HAS_TRIVIAL_DESTRUCTOR (TREE_TYPE (expr)))
	{
	  tree init = TARGET_EXPR_INITIAL (expr);
	  if (TREE_CODE (init) == AGGR_INIT_EXPR
	      && !AGGR_INIT_VIA_CTOR_P (init))
	    {
	      tree fn = AGGR_INIT_EXPR_FN (init);
	      expr = build_call_array_loc (input_location,
					   TREE_TYPE (TREE_TYPE (TREE_TYPE (fn))),
					   fn,
					   aggr_init_expr_nargs (init),
					   AGGR_INIT_EXPR_ARGP (init));
	    }
	}
      break;

    default:;
    }
  expr = resolve_nondeduced_context (expr);
  {
    tree probe = expr;

    if (TREE_CODE (probe) == ADDR_EXPR)
      probe = TREE_OPERAND (expr, 0);
    if (type_unknown_p (probe))
      {
	/* [over.over] enumerates the places where we can take the address
	   of an overloaded function, and this is not one of them.  */
	if (complain & tf_error)
	  switch (implicit)
	    {
	      case ICV_CAST:
		error ("conversion to void "
		       "cannot resolve address of overloaded function");
		break;
	      case ICV_SECOND_OF_COND:
		error ("second operand of conditional expression "
		       "cannot resolve address of overloaded function");
		break;
	      case ICV_THIRD_OF_COND:
		error ("third operand of conditional expression "
		       "cannot resolve address of overloaded function");
		break;
	      case ICV_RIGHT_OF_COMMA:
		error ("right operand of comma operator "
		       "cannot resolve address of overloaded function");
		break;
	      case ICV_LEFT_OF_COMMA:
		error ("left operand of comma operator "
		       "cannot resolve address of overloaded function");
		break;
	      case ICV_STATEMENT:
		error ("statement "
		       "cannot resolve address of overloaded function");
		break;
	      case ICV_THIRD_IN_FOR:
		error ("for increment expression "
		       "cannot resolve address of overloaded function");
		break;
	    }
	else
	  return error_mark_node;
	expr = void_zero_node;
      }
    else if (implicit != ICV_CAST && probe == expr && is_overloaded_fn (probe))
      {
	/* Only warn when there is no &.  */
	if (complain & tf_warning)
	  switch (implicit)
	    {
	      case ICV_SECOND_OF_COND:
	        warning (OPT_Waddress,
			 "second operand of conditional expression "
			 "is a reference, not call, to function %qE", expr);
		break;
	      case ICV_THIRD_OF_COND:
	        warning (OPT_Waddress,
			 "third operand of conditional expression "
			 "is a reference, not call, to function %qE", expr);
		break;
	      case ICV_RIGHT_OF_COMMA:
	        warning (OPT_Waddress,
			 "right operand of comma operator "
			 "is a reference, not call, to function %qE", expr);
		break;
	      case ICV_LEFT_OF_COMMA:
	        warning (OPT_Waddress,
			 "left operand of comma operator "
			 "is a reference, not call, to function %qE", expr);
		break;
	      case ICV_STATEMENT:
	        warning (OPT_Waddress,
			 "statement is a reference, not call, to function %qE",
			 expr);
		break;
	      case ICV_THIRD_IN_FOR:
	        warning (OPT_Waddress,
			 "for increment expression "
			 "is a reference, not call, to function %qE", expr);
		break;
	      default:
	        gcc_unreachable ();
	    }

	if (TREE_CODE (expr) == COMPONENT_REF)
	  expr = TREE_OPERAND (expr, 0);
      }
  }

  if (expr != error_mark_node && !VOID_TYPE_P (TREE_TYPE (expr)))
    {
      if (implicit != ICV_CAST
	  && warn_unused_value
	  && !TREE_NO_WARNING (expr)
	  && !processing_template_decl)
	{
	  /* The middle end does not warn about expressions that have
	     been explicitly cast to void, so we must do so here.  */
	  if (!TREE_SIDE_EFFECTS (expr)) {
            if (complain & tf_warning)
	      switch (implicit)
		{
		  case ICV_SECOND_OF_COND:
		    warning (OPT_Wunused_value,
			     "second operand of conditional expression has no effect");
		    break;
		  case ICV_THIRD_OF_COND:
		    warning (OPT_Wunused_value,
		    	     "third operand of conditional expression has no effect");
		    break;
		  case ICV_RIGHT_OF_COMMA:
		    warning (OPT_Wunused_value,
		    	     "right operand of comma operator has no effect");
		    break;
		  case ICV_LEFT_OF_COMMA:
		    warning (OPT_Wunused_value,
		    	     "left operand of comma operator has no effect");
		    break;
		  case ICV_STATEMENT:
		    warning (OPT_Wunused_value,
		    	     "statement has no effect");
		    break;
		  case ICV_THIRD_IN_FOR:
		    warning (OPT_Wunused_value,
		    	     "for increment expression has no effect");
		    break;
		  default:
		    gcc_unreachable ();
		}
          }
	  else
	    {
	      tree e;
	      enum tree_code code;
	      enum tree_code_class tclass;

	      e = expr;
	      /* We might like to warn about (say) "(int) f()", as the
		 cast has no effect, but the compiler itself will
		 generate implicit conversions under some
		 circumstances.  (For example a block copy will be
		 turned into a call to "__builtin_memcpy", with a
		 conversion of the return value to an appropriate
		 type.)  So, to avoid false positives, we strip
		 conversions.  Do not use STRIP_NOPs because it will
		 not strip conversions to "void", as that is not a
		 mode-preserving conversion.  */
	      while (TREE_CODE (e) == NOP_EXPR)
		e = TREE_OPERAND (e, 0);

	      code = TREE_CODE (e);
	      tclass = TREE_CODE_CLASS (code);
	      if ((tclass == tcc_comparison
		   || tclass == tcc_unary
		   || (tclass == tcc_binary
		       && !(code == MODIFY_EXPR
			    || code == INIT_EXPR
			    || code == PREDECREMENT_EXPR
			    || code == PREINCREMENT_EXPR
			    || code == POSTDECREMENT_EXPR
			    || code == POSTINCREMENT_EXPR)))
                  && (complain & tf_warning))
		warning (OPT_Wunused_value, "value computed is not used");
	    }
	}
      expr = build1 (CONVERT_EXPR, void_type_node, expr);
    }
  if (! TREE_SIDE_EFFECTS (expr))
    expr = void_zero_node;
  return expr;
}