/* Functions related to invoking methods and overloaded functions.
Copyright (C) 1987, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
- 2010, 2011
+ 2010, 2011, 2012
Free Software Foundation, Inc.
Contributed by Michael Tiemann (tiemann@cygnus.com) and
modified by Brendan Kehoe (brendan@cygnus.com).
/* The next conversion in the chain. Since the conversions are
arranged from outermost to innermost, the NEXT conversion will
actually be performed before this conversion. This variant is
- used only when KIND is neither ck_identity nor ck_ambig. */
+ used only when KIND is neither ck_identity, ck_ambig nor
+ ck_list. Please use the next_conversion function instead
+ of using this field directly. */
conversion *next;
/* The expression at the beginning of the conversion chain. This
variant is used only if KIND is ck_identity or ck_ambig. */
tree expr;
- /* The array of conversions for an initializer_list. */
+ /* The array of conversions for an initializer_list, so this
+ variant is used only when KIN D is ck_list. */
conversion **list;
} u;
/* The function candidate corresponding to this conversion
static conversion *reference_binding (tree, tree, tree, bool, int);
static conversion *build_conv (conversion_kind, tree, conversion *);
static conversion *build_list_conv (tree, tree, int);
+static conversion *next_conversion (conversion *);
static bool is_subseq (conversion *, conversion *);
static conversion *maybe_handle_ref_bind (conversion **);
static void maybe_handle_implicit_object (conversion **);
tree access_path;
/* If FN is a non-static member function, the binfo indicating the
subobject to which the `this' pointer should be converted if FN
- is selected by overload resolution. The type pointed to the by
+ is selected by overload resolution. The type pointed to by
the `this' pointer must correspond to the most derived class
indicated by the CONVERSION_PATH. */
tree conversion_path;
{
/* Core issue 903 says only literal 0 is a null pointer constant. */
if (cxx_dialect < cxx0x)
- {
- t = integral_constant_value (t);
- STRIP_NOPS (t);
- }
+ t = integral_constant_value (t);
+ STRIP_NOPS (t);
if (integer_zerop (t) && !TREE_OVERFLOW (t))
return true;
}
return t;
}
+/* Return the next conversion of the conversion chain (if applicable),
+ or NULL otherwise. Please use this function instead of directly
+ accessing fields of struct conversion. */
+
+static conversion *
+next_conversion (conversion *conv)
+{
+ if (conv == NULL
+ || conv->kind == ck_identity
+ || conv->kind == ck_ambig
+ || conv->kind == ck_list)
+ return NULL;
+ return conv->u.next;
+}
+
/* Subroutine of build_aggr_conv: check whether CTOR, a braced-init-list,
is a valid aggregate initializer for array type ATYPE. */
tree tbase = class_of_this_parm (tofn);
if (!DERIVED_FROM_P (fbase, tbase)
- || !same_type_p (TREE_TYPE (fromfn), TREE_TYPE (tofn))
- || !compparms (TREE_CHAIN (TYPE_ARG_TYPES (fromfn)),
- TREE_CHAIN (TYPE_ARG_TYPES (tofn)))
- || cp_type_quals (fbase) != cp_type_quals (tbase))
+ || !same_type_p (static_fn_type (fromfn),
+ static_fn_type (tofn)))
return NULL;
from = build_memfn_type (fromfn, tbase, cp_type_quals (tbase));
|| expr == error_mark_node)
return NULL;
+ /* Other flags only apply to the primary function in overload
+ resolution, or after we've chosen one. */
+ flags &= (LOOKUP_ONLYCONVERTING|LOOKUP_NO_CONVERSION|LOOKUP_COPY_PARM
+ |LOOKUP_NO_TEMP_BIND|LOOKUP_NO_RVAL_BIND|LOOKUP_PREFER_RVALUE
+ |LOOKUP_NO_NARROWING|LOOKUP_PROTECT);
+
if (TREE_CODE (to) == REFERENCE_TYPE)
conv = reference_binding (to, from, expr, c_cast_p, flags);
else
&& (flags & LOOKUP_NO_CONVERSION) == 0)
{
struct z_candidate *cand;
- int convflags = (flags & (LOOKUP_NO_TEMP_BIND|LOOKUP_ONLYCONVERTING
- |LOOKUP_NO_NARROWING));
if (CLASS_TYPE_P (to)
&& BRACE_ENCLOSED_INITIALIZER_P (expr)
&& !CLASSTYPE_NON_AGGREGATE (complete_type (to)))
return build_aggr_conv (to, expr, flags);
- cand = build_user_type_conversion_1 (to, expr, convflags);
+ cand = build_user_type_conversion_1 (to, expr, flags);
if (cand)
conv = cand->second_conv;
to handle move constructors and template constructors as well;
the standardese should soon be updated similarly. */
if (ctype && i == 0 && (len-skip == 1)
- && !(flags & LOOKUP_ONLYCONVERTING)
&& DECL_CONSTRUCTOR_P (fn)
&& parmtype != error_mark_node
&& (same_type_ignoring_top_level_qualifiers_p
(non_reference (parmtype), ctype)))
{
- lflags |= LOOKUP_COPY_PARM;
+ if (!(flags & LOOKUP_ONLYCONVERTING))
+ lflags |= LOOKUP_COPY_PARM;
/* We allow user-defined conversions within init-lists, but
- not for the copy constructor. */
- if (flags & LOOKUP_NO_COPY_CTOR_CONVERSION)
+ don't list-initialize the copy parm, as that would mean
+ using two levels of braces for the same type. */
+ if ((flags & LOOKUP_LIST_INIT_CTOR)
+ && BRACE_ENCLOSED_INITIALIZER_P (arg))
lflags |= LOOKUP_NO_CONVERSION;
}
else
|| MAYBE_CLASS_TYPE_P (type1)
|| TREE_CODE (type1) == ENUMERAL_TYPE))
{
+ if (TYPE_PTR_P (type1) || TYPE_PTR_TO_MEMBER_P (type1))
+ {
+ tree cptype = composite_pointer_type (type1, type2,
+ error_mark_node,
+ error_mark_node,
+ CPO_CONVERSION,
+ tf_none);
+ if (cptype != error_mark_node)
+ {
+ build_builtin_candidate
+ (candidates, fnname, cptype, cptype, args, argtypes, flags);
+ return;
+ }
+ }
+
build_builtin_candidate
(candidates, fnname, type1, type1, args, argtypes, flags);
build_builtin_candidate
gcc_assert (*candidates == NULL);
- /* For list-initialization we consider explicit constructors, but
- give an error if one is selected. */
- flags &= ~LOOKUP_ONLYCONVERTING;
+ /* We're looking for a ctor for list-initialization. */
+ flags |= LOOKUP_LIST_INIT_CTOR;
/* And we don't allow narrowing conversions. We also use this flag to
avoid the copy constructor call for copy-list-initialization. */
flags |= LOOKUP_NO_NARROWING;
flags &= ~LOOKUP_LIST_ONLY;
/* We allow more user-defined conversions within an init-list. */
flags &= ~LOOKUP_NO_CONVERSION;
- /* But not for the copy ctor. */
- flags |= LOOKUP_NO_COPY_CTOR_CONVERSION;
add_candidates (fns, first_arg, args, NULL_TREE,
explicit_targs, template_only, conversion_path,
build_user_type_conversion_1 (tree totype, tree expr, int flags)
{
struct z_candidate *candidates, *cand;
- tree fromtype = TREE_TYPE (expr);
+ tree fromtype;
tree ctors = NULL_TREE;
tree conv_fns = NULL_TREE;
conversion *conv = NULL;
bool any_viable_p;
int convflags;
+ if (!expr)
+ return NULL;
+
+ fromtype = TREE_TYPE (expr);
+
/* We represent conversion within a hierarchy using RVALUE_CONV and
BASE_CONV, as specified by [over.best.ics]; these become plain
constructor calls, as specified in [dcl.init]. */
return error_mark_node;
}
+ if (flag_tm)
+ tm_malloc_replacement (fn);
+
/* If this function was found without using argument dependent
lookup, then we want to ignore any undeclared friend
functions. */
&& TREE_CODE (arg3_type) == ENUMERAL_TYPE)
{
if (complain & tf_warning)
- warning (0,
+ warning (OPT_Wenum_compare,
"enumeral mismatch in conditional expression: %qT vs %qT",
arg2_type, arg3_type);
}
if (DECL_CONSTRUCTOR_P (fn))
{
check_list_ctor = !!(flags & LOOKUP_LIST_ONLY);
- check_converting = !!(flags & LOOKUP_ONLYCONVERTING);
+ /* For list-initialization we consider explicit constructors
+ and complain if one is chosen. */
+ check_converting
+ = ((flags & (LOOKUP_ONLYCONVERTING|LOOKUP_LIST_INIT_CTOR))
+ == LOOKUP_ONLYCONVERTING);
}
else
{
}
}
-/* Even unsigned enum types promote to signed int. We don't want to
- issue -Wsign-compare warnings for this case. Here ORIG_ARG is the
- original argument and ARG is the argument after any conversions
- have been applied. We set TREE_NO_WARNING if we have added a cast
- from an unsigned enum type to a signed integer type. */
-
-static void
-avoid_sign_compare_warnings (tree orig_arg, tree arg)
-{
- if (orig_arg != NULL_TREE
- && arg != NULL_TREE
- && orig_arg != arg
- && TREE_CODE (TREE_TYPE (orig_arg)) == ENUMERAL_TYPE
- && TYPE_UNSIGNED (TREE_TYPE (orig_arg))
- && INTEGRAL_TYPE_P (TREE_TYPE (arg))
- && !TYPE_UNSIGNED (TREE_TYPE (arg)))
- TREE_NO_WARNING (arg) = 1;
-}
-
static tree
build_new_op_1 (enum tree_code code, int flags, tree arg1, tree arg2, tree arg3,
tree *overload, tsubst_flags_t complain)
{
- tree orig_arg1 = arg1;
- tree orig_arg2 = arg2;
- tree orig_arg3 = arg3;
struct z_candidate *candidates = 0, *cand;
VEC(tree,gc) *arglist;
tree fnname;
return result;
builtin:
- avoid_sign_compare_warnings (orig_arg1, arg1);
- avoid_sign_compare_warnings (orig_arg2, arg2);
- avoid_sign_compare_warnings (orig_arg3, arg3);
-
switch (code)
{
case MODIFY_EXPR:
case POSTDECREMENT_EXPR:
case REALPART_EXPR:
case IMAGPART_EXPR:
+ case ABS_EXPR:
return cp_build_unary_op (code, arg1, candidates != 0, complain);
case ARRAY_REF:
static void
conversion_null_warnings (tree totype, tree expr, tree fn, int argnum)
{
- tree t = non_reference (totype);
-
/* Issue warnings about peculiar, but valid, uses of NULL. */
- if (expr == null_node && TREE_CODE (t) != BOOLEAN_TYPE && ARITHMETIC_TYPE_P (t))
+ if (expr == null_node && TREE_CODE (totype) != BOOLEAN_TYPE
+ && ARITHMETIC_TYPE_P (totype))
{
if (fn)
warning_at (input_location, OPT_Wconversion_null,
argnum, fn);
else
warning_at (input_location, OPT_Wconversion_null,
- "converting to non-pointer type %qT from NULL", t);
+ "converting to non-pointer type %qT from NULL", totype);
}
/* Issue warnings if "false" is converted to a NULL pointer */
- else if (expr == boolean_false_node && POINTER_TYPE_P (t))
+ else if (TREE_CODE (TREE_TYPE (expr)) == BOOLEAN_TYPE
+ && TYPE_PTR_P (totype))
{
if (fn)
warning_at (input_location, OPT_Wconversion_null,
"of %qD", argnum, fn);
else
warning_at (input_location, OPT_Wconversion_null,
- "converting %<false%> to pointer type %qT", t);
+ "converting %<false%> to pointer type %qT", totype);
}
}
&& BRACE_ENCLOSED_INITIALIZER_P (CONSTRUCTOR_ELT (expr, 0)->value))
permerror (input_location, "too many braces around initializer for %qT", totype);
- for (; t; t = t->u.next)
+ for (; t ; t = next_conversion (t))
{
if (t->kind == ck_user && t->cand->reason)
{
&& CONSTRUCTOR_NELTS (expr) == 0
&& TYPE_HAS_DEFAULT_CONSTRUCTOR (totype))
{
+ bool direct = CONSTRUCTOR_IS_DIRECT_INIT (expr);
expr = build_value_init (totype, complain);
expr = get_target_expr_sfinae (expr, complain);
if (expr != error_mark_node)
- TARGET_EXPR_LIST_INIT_P (expr) = true;
+ {
+ TARGET_EXPR_LIST_INIT_P (expr) = true;
+ TARGET_EXPR_DIRECT_INIT_P (expr) = direct;
+ }
return expr;
}
/* When converting from an init list we consider explicit
constructors, but actually trying to call one is an error. */
if (DECL_NONCONVERTING_P (convfn) && DECL_CONSTRUCTOR_P (convfn)
+ /* Unless this is for direct-list-initialization. */
+ && !(BRACE_ENCLOSED_INITIALIZER_P (expr)
+ && CONSTRUCTOR_IS_DIRECT_INIT (expr))
/* Unless we're calling it for value-initialization from an
empty list, since that is handled separately in 8.5.4. */
&& cand->num_convs > 0)
leave it as an lvalue. */
if (inner >= 0)
{
- expr = decl_constant_value (expr);
+ expr = decl_constant_value_safe (expr);
if (expr == null_node && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (totype))
/* If __null has been converted to an integer type, we do not
want to warn about uses of EXPR as an integer, rather than
(elttype, cp_type_quals (elttype) | TYPE_QUAL_CONST);
array = build_array_of_n_type (elttype, len);
array = finish_compound_literal (array, new_ctor, complain);
+ /* Take the address explicitly rather than via decay_conversion
+ to avoid the error about taking the address of a temporary. */
+ array = cp_build_addr_expr (array, complain);
+ array = cp_convert (build_pointer_type (elttype), array);
/* Build up the initializer_list object. */
totype = complete_type (totype);
field = next_initializable_field (TYPE_FIELDS (totype));
- CONSTRUCTOR_APPEND_ELT (vec, field, decay_conversion (array));
+ CONSTRUCTOR_APPEND_ELT (vec, field, array);
field = next_initializable_field (DECL_CHAIN (field));
CONSTRUCTOR_APPEND_ELT (vec, field, size_int (len));
new_ctor = build_constructor (totype, vec);
we must not perform access checks here. */
push_deferring_access_checks (dk_no_check);
+ /* We must make a copy of ARG, in case subsequent processing
+ alters any part of it. */
arg = break_out_target_exprs (arg);
if (TREE_CODE (arg) == CONSTRUCTOR)
{
}
else
{
- /* We must make a copy of ARG, in case subsequent processing
- alters any part of it. For example, during gimplification a
- cast of the form (T) &X::f (where "f" is a member function)
- will lead to replacing the PTRMEM_CST for &X::f with a
- VAR_DECL. We can avoid the copy for constants, since they
- are never modified in place. */
- if (!CONSTANT_CLASS_P (arg))
- arg = unshare_expr (arg);
arg = convert_for_initialization (0, type, arg, LOOKUP_IMPLICIT,
ICR_DEFAULT_ARGUMENT, fn, parmnum,
tf_warning_or_error);
return error_mark_node;
}
+ /* See if the function member or the whole class type is declared
+ final and the call can be devirtualized. */
+ if (DECL_FINAL_P (fn)
+ || CLASSTYPE_FINAL (TYPE_METHOD_BASETYPE (TREE_TYPE (fn))))
+ flags |= LOOKUP_NONVIRTUAL;
+
/* [class.mfct.nonstatic]: If a nonstatic member function of a class
X is called for an object that is not of type X, or of a type
derived from X, the behavior is undefined.
converted_arg = build_base_path (PLUS_EXPR,
arg,
cand->conversion_path,
- 1);
+ 1, complain);
/* Check that the base class is accessible. */
if (!accessible_base_p (TREE_TYPE (argtype),
BINFO_TYPE (cand->conversion_path), true))
base_binfo = lookup_base (TREE_TYPE (TREE_TYPE (converted_arg)),
TREE_TYPE (parmtype), ba_unique, NULL);
converted_arg = build_base_path (PLUS_EXPR, converted_arg,
- base_binfo, 1);
+ base_binfo, 1, complain);
argarray[j++] = converted_arg;
parm = TREE_CHAIN (parm);
/* Default arguments */
for (; parm && parm != void_list_node; parm = TREE_CHAIN (parm), i++)
- argarray[j++] = convert_default_arg (TREE_VALUE (parm),
- TREE_PURPOSE (parm),
- fn, i - is_method);
+ {
+ if (TREE_VALUE (parm) == error_mark_node)
+ return error_mark_node;
+ argarray[j++] = convert_default_arg (TREE_VALUE (parm),
+ TREE_PURPOSE (parm),
+ fn, i - is_method);
+ }
+
/* Ellipsis */
for (; arg_index < VEC_length (tree, args); ++arg_index)
{
if (TREE_DEPRECATED (fn))
warn_deprecated_use (fn, NULL_TREE);
- argarray[0] = build_base_path (PLUS_EXPR, argarray[0], binfo, 1);
+ argarray[0] = build_base_path (PLUS_EXPR, argarray[0], binfo, 1,
+ complain);
if (TREE_SIDE_EFFECTS (argarray[0]))
argarray[0] = save_expr (argarray[0]);
t = build_pointer_type (TREE_TYPE (fn));
/* However, for assignment operators, we must convert
dynamically if the base is virtual. */
instance = build_base_path (PLUS_EXPR, instance,
- binfo, /*nonnull=*/1);
+ binfo, /*nonnull=*/1, complain);
}
}
current_in_charge_parm, integer_zero_node),
current_vtt_parm,
vtt);
- gcc_assert (BINFO_SUBVTT_INDEX (binfo));
- sub_vtt = fold_build_pointer_plus (vtt, BINFO_SUBVTT_INDEX (binfo));
+ if (BINFO_SUBVTT_INDEX (binfo))
+ sub_vtt = fold_build_pointer_plus (vtt, BINFO_SUBVTT_INDEX (binfo));
+ else
+ sub_vtt = vtt;
if (args == NULL)
{
&& CONSTRUCTOR_IS_DIRECT_INIT (VEC_index (tree, *args, 0)))
{
tree init_list = VEC_index (tree, *args, 0);
+ tree init = NULL_TREE;
gcc_assert (VEC_length (tree, *args) == 1
&& !(flags & LOOKUP_ONLYCONVERTING));
if (CONSTRUCTOR_NELTS (init_list) == 0
&& TYPE_HAS_DEFAULT_CONSTRUCTOR (basetype)
&& !processing_template_decl)
+ init = build_value_init (basetype, complain);
+
+ /* If BASETYPE is an aggregate, we need to do aggregate
+ initialization. */
+ else if (CP_AGGREGATE_TYPE_P (basetype))
+ init = digest_init (basetype, init_list, complain);
+
+ if (init)
{
- tree ob, init = build_value_init (basetype, complain);
+ tree ob;
if (integer_zerop (instance_ptr))
return get_target_expr_sfinae (init, complain);
ob = build_fold_indirect_ref (instance_ptr);
return init;
}
+ /* Otherwise go ahead with overload resolution. */
add_list_candidates (fns, first_mem_arg, init_list,
basetype, explicit_targs, template_only,
conversion_path, access_binfo, flags, &candidates);
}
else
{
+ /* Optimize away vtable lookup if we know that this function
+ can't be overridden. */
if (DECL_VINDEX (fn) && ! (flags & LOOKUP_NONVIRTUAL)
&& resolves_to_fixed_type_p (instance, 0))
flags |= LOOKUP_NONVIRTUAL;
Specifically, we need to do the reference binding comparison at the
end of this function. */
- if (ics1->user_conv_p || ics1->kind == ck_list)
+ if (ics1->user_conv_p || ics1->kind == ck_list || ics1->kind == ck_aggr)
{
conversion *t1;
conversion *t2;
types to which the references refer are the same type except for
top-level cv-qualifiers, and the type to which the reference
initialized by S2 refers is more cv-qualified than the type to
- which the reference initialized by S1 refers */
+ which the reference initialized by S1 refers.
+
+ DR 1328 [over.match.best]: the context is an initialization by
+ conversion function for direct reference binding (13.3.1.6) of a
+ reference to function type, the return type of F1 is the same kind of
+ reference (i.e. lvalue or rvalue) as the reference being initialized,
+ and the return type of F2 is not. */
if (ref_conv1 && ref_conv2)
{
- if (!ref_conv1->this_p && !ref_conv2->this_p)
+ if (!ref_conv1->this_p && !ref_conv2->this_p
+ && (ref_conv1->rvaluedness_matches_p
+ != ref_conv2->rvaluedness_matches_p)
+ && (same_type_p (ref_conv1->type, ref_conv2->type)
+ || (TYPE_REF_IS_RVALUE (ref_conv1->type)
+ != TYPE_REF_IS_RVALUE (ref_conv2->type))))
{
- if (ref_conv1->rvaluedness_matches_p
- > ref_conv2->rvaluedness_matches_p)
- return 1;
- if (ref_conv2->rvaluedness_matches_p
- > ref_conv1->rvaluedness_matches_p)
- return -1;
+ return (ref_conv1->rvaluedness_matches_p
+ - ref_conv2->rvaluedness_matches_p);
}
if (same_type_ignoring_top_level_qualifiers_p (to_type1, to_type2))
int static_1 = DECL_STATIC_FUNCTION_P (cand1->fn);
int static_2 = DECL_STATIC_FUNCTION_P (cand2->fn);
+ if (DECL_CONSTRUCTOR_P (cand1->fn)
+ && is_list_ctor (cand1->fn) != is_list_ctor (cand2->fn))
+ /* We're comparing a near-match list constructor and a near-match
+ non-list constructor. Just treat them as unordered. */
+ return 0;
+
gcc_assert (static_1 != static_2);
if (static_1)
if (winner)
return winner;
+ /* DR 495 moved this tiebreaker above the template ones. */
+ /* or, if not that,
+ the context is an initialization by user-defined conversion (see
+ _dcl.init_ and _over.match.user_) and the standard conversion
+ sequence from the return type of F1 to the destination type (i.e.,
+ the type of the entity being initialized) is a better conversion
+ sequence than the standard conversion sequence from the return type
+ of F2 to the destination type. */
+
+ if (cand1->second_conv)
+ {
+ winner = compare_ics (cand1->second_conv, cand2->second_conv);
+ if (winner)
+ return winner;
+ }
+
/* or, if not that,
F1 is a non-template function and F2 is a template function
specialization. */
return winner;
}
- /* or, if not that,
- the context is an initialization by user-defined conversion (see
- _dcl.init_ and _over.match.user_) and the standard conversion
- sequence from the return type of F1 to the destination type (i.e.,
- the type of the entity being initialized) is a better conversion
- sequence than the standard conversion sequence from the return type
- of F2 to the destination type. */
-
- if (cand1->second_conv)
- {
- winner = compare_ics (cand1->second_conv, cand2->second_conv);
- if (winner)
- return winner;
- }
-
/* Check whether we can discard a builtin candidate, either because we
have two identical ones or matching builtin and non-builtin candidates.
}
expr = error_mark_node;
}
- else if (processing_template_decl)
+ else if (processing_template_decl && conv->kind != ck_identity)
{
/* In a template, we are only concerned about determining the
type of non-dependent expressions, so we do not have to
- perform the actual conversion. */
- if (TREE_TYPE (expr) != type)
- expr = build_nop (type, expr);
+ perform the actual conversion. But for initializers, we
+ need to be able to perform it at instantiation
+ (or fold_non_dependent_expr) time. */
+ expr = build1 (IMPLICIT_CONV_EXPR, type, expr);
+ if (!(flags & LOOKUP_ONLYCONVERTING))
+ IMPLICIT_CONV_EXPR_DIRECT_INIT (expr) = true;
}
else
expr = convert_like (conv, expr, complain);
return expr;
}
+/* When initializing a reference that lasts longer than a full-expression,
+ this special rule applies:
+
+ [class.temporary]
+
+ The temporary to which the reference is bound or the temporary
+ that is the complete object to which the reference is bound
+ persists for the lifetime of the reference.
+
+ The temporaries created during the evaluation of the expression
+ initializing the reference, except the temporary to which the
+ reference is bound, are destroyed at the end of the
+ full-expression in which they are created.
+
+ In that case, we store the converted expression into a new
+ VAR_DECL in a new scope.
+
+ However, we want to be careful not to create temporaries when
+ they are not required. For example, given:
+
+ struct B {};
+ struct D : public B {};
+ D f();
+ const B& b = f();
+
+ there is no need to copy the return value from "f"; we can just
+ extend its lifetime. Similarly, given:
+
+ struct S {};
+ struct T { operator S(); };
+ T t;
+ const S& s = t;
+
+ we can extend the lifetime of the return value of the conversion
+ operator.
+
+ The next several functions are involved in this lifetime extension. */
+
/* DECL is a VAR_DECL whose type is a REFERENCE_TYPE. The reference
is being bound to a temporary. Create and return a new VAR_DECL
with the indicated TYPE; this variable will store the value to
if (TREE_STATIC (decl))
{
/* Namespace-scope or local static; give it a mangled name. */
+ /* FIXME share comdat with decl? */
tree name;
TREE_STATIC (var) = 1;
cleanup for the new variable is returned through CLEANUP, and the
code to initialize the new variable is returned through INITP. */
-tree
-set_up_extended_ref_temp (tree decl, tree expr, tree *cleanup, tree *initp)
+static tree
+set_up_extended_ref_temp (tree decl, tree expr, VEC(tree,gc) **cleanups,
+ tree *initp)
{
tree init;
tree type;
if (TREE_CODE (expr) != TARGET_EXPR)
expr = get_target_expr (expr);
+ if (TREE_CODE (decl) == FIELD_DECL
+ && extra_warnings && !TREE_NO_WARNING (decl))
+ {
+ warning (OPT_Wextra, "a temporary bound to %qD only persists "
+ "until the constructor exits", decl);
+ TREE_NO_WARNING (decl) = true;
+ }
+
+ /* Recursively extend temps in this initializer. */
+ TARGET_EXPR_INITIAL (expr)
+ = extend_ref_init_temps (decl, TARGET_EXPR_INITIAL (expr), cleanups);
+
/* If the initializer is constant, put it in DECL_INITIAL so we get
static initialization and use in constant expressions. */
init = maybe_constant_init (expr);
if (TREE_STATIC (var))
init = add_stmt_to_compound (init, register_dtor_fn (var));
else
- *cleanup = cxx_maybe_build_cleanup (var, tf_warning_or_error);
+ {
+ tree cleanup = cxx_maybe_build_cleanup (var, tf_warning_or_error);
+ if (cleanup)
+ VEC_safe_push (tree, gc, *cleanups, cleanup);
+ }
/* We must be careful to destroy the temporary only
after its initialization has taken place. If the
}
/* Convert EXPR to the indicated reference TYPE, in a way suitable for
- initializing a variable of that TYPE. If DECL is non-NULL, it is
- the VAR_DECL being initialized with the EXPR. (In that case, the
- type of DECL will be TYPE.) If DECL is non-NULL, then CLEANUP must
- also be non-NULL, and with *CLEANUP initialized to NULL. Upon
- return, if *CLEANUP is no longer NULL, it will be an expression
- that should be pushed as a cleanup after the returned expression
- is used to initialize DECL.
-
- Return the converted expression. */
+ initializing a variable of that TYPE. */
tree
-initialize_reference (tree type, tree expr, tree decl, tree *cleanup,
+initialize_reference (tree type, tree expr,
int flags, tsubst_flags_t complain)
{
conversion *conv;
return error_mark_node;
}
- /* If DECL is non-NULL, then this special rule applies:
-
- [class.temporary]
-
- The temporary to which the reference is bound or the temporary
- that is the complete object to which the reference is bound
- persists for the lifetime of the reference.
+ gcc_assert (conv->kind == ck_ref_bind);
- The temporaries created during the evaluation of the expression
- initializing the reference, except the temporary to which the
- reference is bound, are destroyed at the end of the
- full-expression in which they are created.
+ /* Perform the conversion. */
+ expr = convert_like (conv, expr, complain);
- In that case, we store the converted expression into a new
- VAR_DECL in a new scope.
+ /* Free all the conversions we allocated. */
+ obstack_free (&conversion_obstack, p);
- However, we want to be careful not to create temporaries when
- they are not required. For example, given:
+ return expr;
+}
- struct B {};
- struct D : public B {};
- D f();
- const B& b = f();
+/* Subroutine of extend_ref_init_temps. Possibly extend one initializer,
+ which is bound either to a reference or a std::initializer_list. */
- there is no need to copy the return value from "f"; we can just
- extend its lifetime. Similarly, given:
+static tree
+extend_ref_init_temps_1 (tree decl, tree init, VEC(tree,gc) **cleanups)
+{
+ tree sub = init;
+ tree *p;
+ STRIP_NOPS (sub);
+ if (TREE_CODE (sub) != ADDR_EXPR)
+ return init;
+ /* Deal with binding to a subobject. */
+ for (p = &TREE_OPERAND (sub, 0); TREE_CODE (*p) == COMPONENT_REF; )
+ p = &TREE_OPERAND (*p, 0);
+ if (TREE_CODE (*p) == TARGET_EXPR)
+ {
+ tree subinit = NULL_TREE;
+ *p = set_up_extended_ref_temp (decl, *p, cleanups, &subinit);
+ if (subinit)
+ init = build2 (COMPOUND_EXPR, TREE_TYPE (init), subinit, init);
+ }
+ return init;
+}
- struct S {};
- struct T { operator S(); };
- T t;
- const S& s = t;
+/* INIT is part of the initializer for DECL. If there are any
+ reference or initializer lists being initialized, extend their
+ lifetime to match that of DECL. */
- we can extend the lifetime of the return value of the conversion
- operator. */
- gcc_assert (conv->kind == ck_ref_bind);
- if (decl)
+tree
+extend_ref_init_temps (tree decl, tree init, VEC(tree,gc) **cleanups)
+{
+ tree type = TREE_TYPE (init);
+ if (processing_template_decl)
+ return init;
+ if (TREE_CODE (type) == REFERENCE_TYPE)
+ init = extend_ref_init_temps_1 (decl, init, cleanups);
+ else if (is_std_init_list (type))
{
- tree var;
- tree base_conv_type;
-
- gcc_assert (complain == tf_warning_or_error);
-
- /* Skip over the REF_BIND. */
- conv = conv->u.next;
- /* If the next conversion is a BASE_CONV, skip that too -- but
- remember that the conversion was required. */
- if (conv->kind == ck_base)
+ /* The temporary array underlying a std::initializer_list
+ is handled like a reference temporary. */
+ tree ctor = init;
+ if (TREE_CODE (ctor) == TARGET_EXPR)
+ ctor = TARGET_EXPR_INITIAL (ctor);
+ if (TREE_CODE (ctor) == CONSTRUCTOR)
{
- base_conv_type = conv->type;
- conv = conv->u.next;
- }
- else
- base_conv_type = NULL_TREE;
- /* Perform the remainder of the conversion. */
- expr = convert_like_real (conv, expr,
- /*fn=*/NULL_TREE, /*argnum=*/0,
- /*inner=*/-1,
- /*issue_conversion_warnings=*/true,
- /*c_cast_p=*/false,
- complain);
- if (error_operand_p (expr))
- expr = error_mark_node;
- else
- {
- if (!lvalue_or_rvalue_with_address_p (expr))
- {
- tree init;
- var = set_up_extended_ref_temp (decl, expr, cleanup, &init);
- /* Use its address to initialize the reference variable. */
- expr = build_address (var);
- if (base_conv_type)
- expr = convert_to_base (expr,
- build_pointer_type (base_conv_type),
- /*check_access=*/true,
- /*nonnull=*/true, complain);
- if (init)
- expr = build2 (COMPOUND_EXPR, TREE_TYPE (expr), init, expr);
- }
- else
- /* Take the address of EXPR. */
- expr = cp_build_addr_expr (expr, complain);
- /* If a BASE_CONV was required, perform it now. */
- if (base_conv_type)
- expr = (perform_implicit_conversion
- (build_pointer_type (base_conv_type), expr,
- complain));
- expr = build_nop (type, expr);
+ tree array = CONSTRUCTOR_ELT (ctor, 0)->value;
+ array = extend_ref_init_temps_1 (decl, array, cleanups);
+ CONSTRUCTOR_ELT (ctor, 0)->value = array;
}
}
- else
- /* Perform the conversion. */
- expr = convert_like (conv, expr, complain);
-
- /* Free all the conversions we allocated. */
- obstack_free (&conversion_obstack, p);
+ else if (TREE_CODE (init) == CONSTRUCTOR)
+ {
+ unsigned i;
+ constructor_elt *p;
+ VEC(constructor_elt,gc) *elts = CONSTRUCTOR_ELTS (init);
+ FOR_EACH_VEC_ELT (constructor_elt, elts, i, p)
+ p->value = extend_ref_init_temps (decl, p->value, cleanups);
+ }
- return expr;
+ return init;
}
/* Returns true iff TYPE is some variant of std::initializer_list. */
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