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cvt.c
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cvt.c
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/* Language-level data type conversion for GNU C++.
Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
2011, 2012 Free Software Foundation, Inc.
Hacked by Michael Tiemann (tiemann@cygnus.com)
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>. */
/* This file contains the functions for converting C++ expressions
to different data types. The only entry point is `convert'.
Every language front end must have a `convert' function
but what kind of conversions it does will depend on the language. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "flags.h"
#include "cp-tree.h"
#include "intl.h"
#include "convert.h"
#include "decl.h"
#include "target.h"
static tree cp_convert_to_pointer (tree, tree, tsubst_flags_t);
static tree convert_to_pointer_force (tree, tree, tsubst_flags_t);
static tree build_type_conversion (tree, tree);
static tree build_up_reference (tree, tree, int, tree, tsubst_flags_t);
static void warn_ref_binding (location_t, tree, tree, tree);
/* Change of width--truncation and extension of integers or reals--
is represented with NOP_EXPR. Proper functioning of many things
assumes that no other conversions can be NOP_EXPRs.
Conversion between integer and pointer is represented with CONVERT_EXPR.
Converting integer to real uses FLOAT_EXPR
and real to integer uses FIX_TRUNC_EXPR.
Here is a list of all the functions that assume that widening and
narrowing is always done with a NOP_EXPR:
In convert.c, convert_to_integer.
In c-typeck.c, build_binary_op_nodefault (boolean ops),
and c_common_truthvalue_conversion.
In expr.c: expand_expr, for operands of a MULT_EXPR.
In fold-const.c: fold.
In tree.c: get_narrower and get_unwidened.
C++: in multiple-inheritance, converting between pointers may involve
adjusting them by a delta stored within the class definition. */
/* Subroutines of `convert'. */
/* if converting pointer to pointer
if dealing with classes, check for derived->base or vice versa
else if dealing with method pointers, delegate
else convert blindly
else if converting class, pass off to build_type_conversion
else try C-style pointer conversion. */
static tree
cp_convert_to_pointer (tree type, tree expr, tsubst_flags_t complain)
{
tree intype = TREE_TYPE (expr);
enum tree_code form;
tree rval;
location_t loc = EXPR_LOC_OR_HERE (expr);
if (intype == error_mark_node)
return error_mark_node;
if (MAYBE_CLASS_TYPE_P (intype))
{
intype = complete_type (intype);
if (!COMPLETE_TYPE_P (intype))
{
if (complain & tf_error)
error_at (loc, "can%'t convert from incomplete type %qT to %qT",
intype, type);
return error_mark_node;
}
rval = build_type_conversion (type, expr);
if (rval)
{
if ((complain & tf_error)
&& rval == error_mark_node)
error_at (loc, "conversion of %qE from %qT to %qT is ambiguous",
expr, intype, type);
return rval;
}
}
/* Handle anachronistic conversions from (::*)() to cv void* or (*)(). */
if (TREE_CODE (type) == POINTER_TYPE
&& (TREE_CODE (TREE_TYPE (type)) == FUNCTION_TYPE
|| VOID_TYPE_P (TREE_TYPE (type))))
{
if (TYPE_PTRMEMFUNC_P (intype)
|| TREE_CODE (intype) == METHOD_TYPE)
return convert_member_func_to_ptr (type, expr, complain);
if (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE)
return build_nop (type, expr);
intype = TREE_TYPE (expr);
}
if (expr == error_mark_node)
return error_mark_node;
form = TREE_CODE (intype);
if (POINTER_TYPE_P (intype))
{
intype = TYPE_MAIN_VARIANT (intype);
if (TYPE_MAIN_VARIANT (type) != intype
&& TREE_CODE (type) == POINTER_TYPE
&& TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
&& MAYBE_CLASS_TYPE_P (TREE_TYPE (type))
&& MAYBE_CLASS_TYPE_P (TREE_TYPE (intype))
&& TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
{
enum tree_code code = PLUS_EXPR;
tree binfo;
tree intype_class;
tree type_class;
bool same_p;
intype_class = TREE_TYPE (intype);
type_class = TREE_TYPE (type);
same_p = same_type_p (TYPE_MAIN_VARIANT (intype_class),
TYPE_MAIN_VARIANT (type_class));
binfo = NULL_TREE;
/* Try derived to base conversion. */
if (!same_p)
binfo = lookup_base (intype_class, type_class, ba_check, NULL);
if (!same_p && !binfo)
{
/* Try base to derived conversion. */
binfo = lookup_base (type_class, intype_class, ba_check, NULL);
code = MINUS_EXPR;
}
if (binfo == error_mark_node)
return error_mark_node;
if (binfo || same_p)
{
if (binfo)
expr = build_base_path (code, expr, binfo, 0, complain);
/* Add any qualifier conversions. */
return build_nop (type, expr);
}
}
if (TYPE_PTRMEMFUNC_P (type))
{
if (complain & tf_error)
error_at (loc, "cannot convert %qE from type %qT to type %qT",
expr, intype, type);
return error_mark_node;
}
return build_nop (type, expr);
}
else if ((TYPE_PTRDATAMEM_P (type) && TYPE_PTRDATAMEM_P (intype))
|| (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)))
return convert_ptrmem (type, expr, /*allow_inverse_p=*/false,
/*c_cast_p=*/false, complain);
else if (TYPE_PTRMEMFUNC_P (intype))
{
if (!warn_pmf2ptr)
{
if (TREE_CODE (expr) == PTRMEM_CST)
return cp_convert_to_pointer (type, PTRMEM_CST_MEMBER (expr),
complain);
else if (TREE_CODE (expr) == OFFSET_REF)
{
tree object = TREE_OPERAND (expr, 0);
return get_member_function_from_ptrfunc (&object,
TREE_OPERAND (expr, 1),
complain);
}
}
error_at (loc, "cannot convert %qE from type %qT to type %qT",
expr, intype, type);
return error_mark_node;
}
if (null_ptr_cst_p (expr))
{
if ((complain & tf_warning)
&& c_inhibit_evaluation_warnings == 0
&& !NULLPTR_TYPE_P (TREE_TYPE (expr)))
warning_at (loc, OPT_Wzero_as_null_pointer_constant,
"zero as null pointer constant");
if (TYPE_PTRMEMFUNC_P (type))
return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0,
/*c_cast_p=*/false, complain);
if (TYPE_PTRDATAMEM_P (type))
{
/* A NULL pointer-to-member is represented by -1, not by
zero. */
expr = build_int_cst_type (type, -1);
}
else
expr = build_int_cst (type, 0);
return expr;
}
else if (TYPE_PTRMEM_P (type) && INTEGRAL_CODE_P (form))
{
if (complain & tf_error)
error_at (loc, "invalid conversion from %qT to %qT", intype, type);
return error_mark_node;
}
if (INTEGRAL_CODE_P (form))
{
if (TYPE_PRECISION (intype) == POINTER_SIZE)
return build1 (CONVERT_EXPR, type, expr);
expr = cp_convert (c_common_type_for_size (POINTER_SIZE, 0), expr,
complain);
/* Modes may be different but sizes should be the same. There
is supposed to be some integral type that is the same width
as a pointer. */
gcc_assert (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr)))
== GET_MODE_SIZE (TYPE_MODE (type)));
return convert_to_pointer (type, expr);
}
if (type_unknown_p (expr))
return instantiate_type (type, expr, complain);
if (complain & tf_error)
error_at (loc, "cannot convert %qE from type %qT to type %qT",
expr, intype, type);
return error_mark_node;
}
/* Like convert, except permit conversions to take place which
are not normally allowed due to access restrictions
(such as conversion from sub-type to private super-type). */
static tree
convert_to_pointer_force (tree type, tree expr, tsubst_flags_t complain)
{
tree intype = TREE_TYPE (expr);
enum tree_code form = TREE_CODE (intype);
if (form == POINTER_TYPE)
{
intype = TYPE_MAIN_VARIANT (intype);
if (TYPE_MAIN_VARIANT (type) != intype
&& TREE_CODE (TREE_TYPE (type)) == RECORD_TYPE
&& MAYBE_CLASS_TYPE_P (TREE_TYPE (type))
&& MAYBE_CLASS_TYPE_P (TREE_TYPE (intype))
&& TREE_CODE (TREE_TYPE (intype)) == RECORD_TYPE)
{
enum tree_code code = PLUS_EXPR;
tree binfo;
binfo = lookup_base (TREE_TYPE (intype), TREE_TYPE (type),
ba_unique, NULL);
if (!binfo)
{
binfo = lookup_base (TREE_TYPE (type), TREE_TYPE (intype),
ba_unique, NULL);
code = MINUS_EXPR;
}
if (binfo == error_mark_node)
return error_mark_node;
if (binfo)
{
expr = build_base_path (code, expr, binfo, 0, complain);
if (expr == error_mark_node)
return error_mark_node;
/* Add any qualifier conversions. */
if (!same_type_p (TREE_TYPE (TREE_TYPE (expr)),
TREE_TYPE (type)))
expr = build_nop (type, expr);
return expr;
}
}
}
return cp_convert_to_pointer (type, expr, complain);
}
/* We are passing something to a function which requires a reference.
The type we are interested in is in TYPE. The initial
value we have to begin with is in ARG.
FLAGS controls how we manage access checking.
DIRECT_BIND in FLAGS controls how any temporaries are generated.
If DIRECT_BIND is set, DECL is the reference we're binding to. */
static tree
build_up_reference (tree type, tree arg, int flags, tree decl,
tsubst_flags_t complain)
{
tree rval;
tree argtype = TREE_TYPE (arg);
tree target_type = TREE_TYPE (type);
gcc_assert (TREE_CODE (type) == REFERENCE_TYPE);
if ((flags & DIRECT_BIND) && ! real_lvalue_p (arg))
{
/* Create a new temporary variable. We can't just use a TARGET_EXPR
here because it needs to live as long as DECL. */
tree targ = arg;
arg = make_temporary_var_for_ref_to_temp (decl, target_type);
/* Process the initializer for the declaration. */
DECL_INITIAL (arg) = targ;
cp_finish_decl (arg, targ, /*init_const_expr_p=*/false, NULL_TREE,
LOOKUP_ONLYCONVERTING|DIRECT_BIND);
}
else if (!(flags & DIRECT_BIND) && ! lvalue_p (arg))
return get_target_expr (arg);
/* If we had a way to wrap this up, and say, if we ever needed its
address, transform all occurrences of the register, into a memory
reference we could win better. */
rval = cp_build_addr_expr (arg, tf_warning_or_error);
if (rval == error_mark_node)
return error_mark_node;
if ((flags & LOOKUP_PROTECT)
&& TYPE_MAIN_VARIANT (argtype) != TYPE_MAIN_VARIANT (target_type)
&& MAYBE_CLASS_TYPE_P (argtype)
&& MAYBE_CLASS_TYPE_P (target_type))
{
/* We go through lookup_base for the access control. */
tree binfo = lookup_base (argtype, target_type, ba_check, NULL);
if (binfo == error_mark_node)
return error_mark_node;
if (binfo == NULL_TREE)
return error_not_base_type (target_type, argtype);
rval = build_base_path (PLUS_EXPR, rval, binfo, 1, complain);
}
else
rval
= convert_to_pointer_force (build_pointer_type (target_type),
rval, complain);
return build_nop (type, rval);
}
/* Subroutine of convert_to_reference. REFTYPE is the target reference type.
INTYPE is the original rvalue type and DECL is an optional _DECL node
for diagnostics.
[dcl.init.ref] says that if an rvalue is used to
initialize a reference, then the reference must be to a
non-volatile const type. */
static void
warn_ref_binding (location_t loc, tree reftype, tree intype, tree decl)
{
tree ttl = TREE_TYPE (reftype);
if (!CP_TYPE_CONST_NON_VOLATILE_P (ttl))
{
const char *msg;
if (CP_TYPE_VOLATILE_P (ttl) && decl)
msg = G_("initialization of volatile reference type %q#T from "
"rvalue of type %qT");
else if (CP_TYPE_VOLATILE_P (ttl))
msg = G_("conversion to volatile reference type %q#T "
"from rvalue of type %qT");
else if (decl)
msg = G_("initialization of non-const reference type %q#T from "
"rvalue of type %qT");
else
msg = G_("conversion to non-const reference type %q#T from "
"rvalue of type %qT");
permerror (loc, msg, reftype, intype);
}
}
/* For C++: Only need to do one-level references, but cannot
get tripped up on signed/unsigned differences.
DECL is either NULL_TREE or the _DECL node for a reference that is being
initialized. It can be error_mark_node if we don't know the _DECL but
we know it's an initialization. */
tree
convert_to_reference (tree reftype, tree expr, int convtype,
int flags, tree decl, tsubst_flags_t complain)
{
tree type = TYPE_MAIN_VARIANT (TREE_TYPE (reftype));
tree intype;
tree rval = NULL_TREE;
tree rval_as_conversion = NULL_TREE;
bool can_convert_intype_to_type;
location_t loc = EXPR_LOC_OR_HERE (expr);
if (TREE_CODE (type) == FUNCTION_TYPE
&& TREE_TYPE (expr) == unknown_type_node)
expr = instantiate_type (type, expr, complain);
if (expr == error_mark_node)
return error_mark_node;
intype = TREE_TYPE (expr);
gcc_assert (TREE_CODE (intype) != REFERENCE_TYPE);
gcc_assert (TREE_CODE (reftype) == REFERENCE_TYPE);
intype = TYPE_MAIN_VARIANT (intype);
can_convert_intype_to_type = can_convert (type, intype, complain);
if (!can_convert_intype_to_type
&& (convtype & CONV_IMPLICIT) && MAYBE_CLASS_TYPE_P (intype)
&& ! (flags & LOOKUP_NO_CONVERSION))
{
/* Look for a user-defined conversion to lvalue that we can use. */
rval_as_conversion
= build_type_conversion (reftype, expr);
if (rval_as_conversion && rval_as_conversion != error_mark_node
&& real_lvalue_p (rval_as_conversion))
{
expr = rval_as_conversion;
rval_as_conversion = NULL_TREE;
intype = type;
can_convert_intype_to_type = 1;
}
}
if (((convtype & CONV_STATIC) && can_convert (intype, type, complain))
|| ((convtype & CONV_IMPLICIT) && can_convert_intype_to_type))
{
{
tree ttl = TREE_TYPE (reftype);
tree ttr = lvalue_type (expr);
if ((complain & tf_warning)
&& ! real_lvalue_p (expr))
warn_ref_binding (loc, reftype, intype, decl);
if (! (convtype & CONV_CONST)
&& !at_least_as_qualified_p (ttl, ttr))
{
if (complain & tf_error)
permerror (loc, "conversion from %qT to %qT discards qualifiers",
ttr, reftype);
else
return error_mark_node;
}
}
return build_up_reference (reftype, expr, flags, decl, complain);
}
else if ((convtype & CONV_REINTERPRET) && lvalue_p (expr))
{
/* When casting an lvalue to a reference type, just convert into
a pointer to the new type and deference it. This is allowed
by San Diego WP section 5.2.9 paragraph 12, though perhaps it
should be done directly (jason). (int &)ri ---> *(int*)&ri */
/* B* bp; A& ar = (A&)bp; is valid, but it's probably not what they
meant. */
if ((complain & tf_warning)
&& TREE_CODE (intype) == POINTER_TYPE
&& (comptypes (TREE_TYPE (intype), type,
COMPARE_BASE | COMPARE_DERIVED)))
warning_at (loc, 0, "casting %qT to %qT does not dereference pointer",
intype, reftype);
rval = cp_build_addr_expr (expr, complain);
if (rval != error_mark_node)
rval = convert_force (build_pointer_type (TREE_TYPE (reftype)),
rval, 0, complain);
if (rval != error_mark_node)
rval = build1 (NOP_EXPR, reftype, rval);
}
else
{
rval = convert_for_initialization (NULL_TREE, type, expr, flags,
ICR_CONVERTING, 0, 0, complain);
if (rval == NULL_TREE || rval == error_mark_node)
return rval;
if (complain & tf_warning)
warn_ref_binding (loc, reftype, intype, decl);
rval = build_up_reference (reftype, rval, flags, decl, complain);
}
if (rval)
{
/* If we found a way to convert earlier, then use it. */
return rval;
}
if (complain & tf_error)
error_at (loc, "cannot convert type %qT to type %qT", intype, reftype);
return error_mark_node;
}
/* We are using a reference VAL for its value. Bash that reference all the
way down to its lowest form. */
tree
convert_from_reference (tree val)
{
if (TREE_TYPE (val)
&& TREE_CODE (TREE_TYPE (val)) == REFERENCE_TYPE)
{
tree t = TREE_TYPE (TREE_TYPE (val));
tree ref = build1 (INDIRECT_REF, t, val);
mark_exp_read (val);
/* We *must* set TREE_READONLY when dereferencing a pointer to const,
so that we get the proper error message if the result is used
to assign to. Also, &* is supposed to be a no-op. */
TREE_READONLY (ref) = CP_TYPE_CONST_P (t);
TREE_THIS_VOLATILE (ref) = CP_TYPE_VOLATILE_P (t);
TREE_SIDE_EFFECTS (ref)
= (TREE_THIS_VOLATILE (ref) || TREE_SIDE_EFFECTS (val));
val = ref;
}
return val;
}
/* Really perform an lvalue-to-rvalue conversion, including copying an
argument of class type into a temporary. */
tree
force_rvalue (tree expr, tsubst_flags_t complain)
{
tree type = TREE_TYPE (expr);
if (MAYBE_CLASS_TYPE_P (type) && TREE_CODE (expr) != TARGET_EXPR)
{
VEC(tree,gc) *args = make_tree_vector_single (expr);
expr = build_special_member_call (NULL_TREE, complete_ctor_identifier,
&args, type, LOOKUP_NORMAL, complain);
release_tree_vector (args);
expr = build_cplus_new (type, expr, complain);
}
else
expr = decay_conversion (expr, complain);
return expr;
}
/* If EXPR and ORIG are INTEGER_CSTs, return a version of EXPR that has
TREE_OVERFLOW set only if it is set in ORIG. Otherwise, return EXPR
unchanged. */
static tree
ignore_overflows (tree expr, tree orig)
{
if (TREE_CODE (expr) == INTEGER_CST
&& TREE_CODE (orig) == INTEGER_CST
&& TREE_OVERFLOW (expr) != TREE_OVERFLOW (orig))
{
gcc_assert (!TREE_OVERFLOW (orig));
/* Ensure constant sharing. */
expr = build_int_cst_wide (TREE_TYPE (expr),
TREE_INT_CST_LOW (expr),
TREE_INT_CST_HIGH (expr));
}
return expr;
}
/* Fold away simple conversions, but make sure TREE_OVERFLOW is set
properly. */
tree
cp_fold_convert (tree type, tree expr)
{
tree conv = fold_convert (type, expr);
conv = ignore_overflows (conv, expr);
return conv;
}
/* C++ conversions, preference to static cast conversions. */
tree
cp_convert (tree type, tree expr, tsubst_flags_t complain)
{
return ocp_convert (type, expr, CONV_OLD_CONVERT, LOOKUP_NORMAL, complain);
}
/* C++ equivalent of convert_and_check but using cp_convert as the
conversion function.
Convert EXPR to TYPE, warning about conversion problems with constants.
Invoke this function on every expression that is converted implicitly,
i.e. because of language rules and not because of an explicit cast. */
tree
cp_convert_and_check (tree type, tree expr, tsubst_flags_t complain)
{
tree result;
if (TREE_TYPE (expr) == type)
return expr;
result = cp_convert (type, expr, complain);
if ((complain & tf_warning)
&& c_inhibit_evaluation_warnings == 0
&& !TREE_OVERFLOW_P (expr)
&& result != error_mark_node)
warnings_for_convert_and_check (type, expr, result);
return result;
}
/* Conversion...
FLAGS indicates how we should behave. */
tree
ocp_convert (tree type, tree expr, int convtype, int flags,
tsubst_flags_t complain)
{
tree e = expr;
enum tree_code code = TREE_CODE (type);
const char *invalid_conv_diag;
tree e1;
location_t loc = EXPR_LOC_OR_HERE (expr);
if (error_operand_p (e) || type == error_mark_node)
return error_mark_node;
complete_type (type);
complete_type (TREE_TYPE (expr));
if ((invalid_conv_diag
= targetm.invalid_conversion (TREE_TYPE (expr), type)))
{
if (complain & tf_error)
error (invalid_conv_diag);
return error_mark_node;
}
/* FIXME remove when moving to c_fully_fold model. */
/* FIXME do we still need this test? */
if (!CLASS_TYPE_P (type))
e = integral_constant_value (e);
if (error_operand_p (e))
return error_mark_node;
if (MAYBE_CLASS_TYPE_P (type) && (convtype & CONV_FORCE_TEMP))
/* We need a new temporary; don't take this shortcut. */;
else if (same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (e)))
{
if (same_type_p (type, TREE_TYPE (e)))
/* The call to fold will not always remove the NOP_EXPR as
might be expected, since if one of the types is a typedef;
the comparison in fold is just equality of pointers, not a
call to comptypes. We don't call fold in this case because
that can result in infinite recursion; fold will call
convert, which will call ocp_convert, etc. */
return e;
/* For complex data types, we need to perform componentwise
conversion. */
else if (TREE_CODE (type) == COMPLEX_TYPE)
return fold_if_not_in_template (convert_to_complex (type, e));
else if (TREE_CODE (e) == TARGET_EXPR)
{
/* Don't build a NOP_EXPR of class type. Instead, change the
type of the temporary. */
TREE_TYPE (e) = TREE_TYPE (TARGET_EXPR_SLOT (e)) = type;
return e;
}
else
{
/* We shouldn't be treating objects of ADDRESSABLE type as
rvalues. */
gcc_assert (!TREE_ADDRESSABLE (type));
return fold_if_not_in_template (build_nop (type, e));
}
}
e1 = targetm.convert_to_type (type, e);
if (e1)
return e1;
if (code == VOID_TYPE && (convtype & CONV_STATIC))
{
e = convert_to_void (e, ICV_CAST, complain);
return e;
}
if (INTEGRAL_CODE_P (code))
{
tree intype = TREE_TYPE (e);
tree converted;
if (TREE_CODE (type) == ENUMERAL_TYPE)
{
/* enum = enum, enum = int, enum = float, (enum)pointer are all
errors. */
if (((INTEGRAL_OR_ENUMERATION_TYPE_P (intype)
|| TREE_CODE (intype) == REAL_TYPE)
&& ! (convtype & CONV_STATIC))
|| TREE_CODE (intype) == POINTER_TYPE)
{
if (complain & tf_error)
permerror (loc, "conversion from %q#T to %q#T", intype, type);
else
return error_mark_node;
}
/* [expr.static.cast]
8. A value of integral or enumeration type can be explicitly
converted to an enumeration type. The value is unchanged if
the original value is within the range of the enumeration
values. Otherwise, the resulting enumeration value is
unspecified. */
if ((complain & tf_warning)
&& TREE_CODE (e) == INTEGER_CST
&& !int_fits_type_p (e, ENUM_UNDERLYING_TYPE (type)))
warning_at (loc, OPT_Wconversion,
"the result of the conversion is unspecified because "
"%qE is outside the range of type %qT",
expr, type);
}
if (MAYBE_CLASS_TYPE_P (intype))
{
tree rval;
rval = build_type_conversion (type, e);
if (rval)
return rval;
if (complain & tf_error)
error_at (loc, "%q#T used where a %qT was expected", intype, type);
return error_mark_node;
}
if (code == BOOLEAN_TYPE)
{
if (TREE_CODE (intype) == VOID_TYPE)
{
if (complain & tf_error)
error_at (loc,
"could not convert %qE from %<void%> to %<bool%>",
expr);
return error_mark_node;
}
/* We can't implicitly convert a scoped enum to bool, so convert
to the underlying type first. */
if (SCOPED_ENUM_P (intype) && (convtype & CONV_STATIC))
e = build_nop (ENUM_UNDERLYING_TYPE (intype), e);
return cp_truthvalue_conversion (e);
}
converted = fold_if_not_in_template (convert_to_integer (type, e));
/* Ignore any integer overflow caused by the conversion. */
return ignore_overflows (converted, e);
}
if (NULLPTR_TYPE_P (type) && e && null_ptr_cst_p (e))
return nullptr_node;
if (POINTER_TYPE_P (type) || TYPE_PTRMEM_P (type))
return fold_if_not_in_template (cp_convert_to_pointer (type, e, complain));
if (code == VECTOR_TYPE)
{
tree in_vtype = TREE_TYPE (e);
if (MAYBE_CLASS_TYPE_P (in_vtype))
{
tree ret_val;
ret_val = build_type_conversion (type, e);
if (ret_val)
return ret_val;
if (complain & tf_error)
error_at (loc, "%q#T used where a %qT was expected",
in_vtype, type);
return error_mark_node;
}
return fold_if_not_in_template (convert_to_vector (type, e));
}
if (code == REAL_TYPE || code == COMPLEX_TYPE)
{
if (MAYBE_CLASS_TYPE_P (TREE_TYPE (e)))
{
tree rval;
rval = build_type_conversion (type, e);
if (rval)
return rval;
else if (complain & tf_error)
error_at (loc,
"%q#T used where a floating point value was expected",
TREE_TYPE (e));
}
if (code == REAL_TYPE)
return fold_if_not_in_template (convert_to_real (type, e));
else if (code == COMPLEX_TYPE)
return fold_if_not_in_template (convert_to_complex (type, e));
}
/* New C++ semantics: since assignment is now based on
memberwise copying, if the rhs type is derived from the
lhs type, then we may still do a conversion. */
if (RECORD_OR_UNION_CODE_P (code))
{
tree dtype = TREE_TYPE (e);
tree ctor = NULL_TREE;
dtype = TYPE_MAIN_VARIANT (dtype);
/* Conversion between aggregate types. New C++ semantics allow
objects of derived type to be cast to objects of base type.
Old semantics only allowed this between pointers.
There may be some ambiguity between using a constructor
vs. using a type conversion operator when both apply. */
ctor = e;
if (abstract_virtuals_error (NULL_TREE, type))
return error_mark_node;
if (BRACE_ENCLOSED_INITIALIZER_P (ctor))
ctor = perform_implicit_conversion (type, ctor, complain);
else if ((flags & LOOKUP_ONLYCONVERTING)
&& ! (CLASS_TYPE_P (dtype) && DERIVED_FROM_P (type, dtype)))
/* For copy-initialization, first we create a temp of the proper type
with a user-defined conversion sequence, then we direct-initialize
the target with the temp (see [dcl.init]). */
ctor = build_user_type_conversion (type, ctor, flags, complain);
else
{
VEC(tree,gc) *ctor_vec = make_tree_vector_single (ctor);
ctor = build_special_member_call (NULL_TREE,
complete_ctor_identifier,
&ctor_vec,
type, flags, complain);
release_tree_vector (ctor_vec);
}
if (ctor)
return build_cplus_new (type, ctor, complain);
}
if (complain & tf_error)
{
/* If the conversion failed and expr was an invalid use of pointer to
member function, try to report a meaningful error. */
if (invalid_nonstatic_memfn_p (expr, complain))
/* We displayed the error message. */;
else
error_at (loc, "conversion from %qT to non-scalar type %qT requested",
TREE_TYPE (expr), type);
}
return error_mark_node;
}
/* When an expression is used in a void context, its value is discarded and
no lvalue-rvalue and similar conversions happen [expr.static.cast/4,
stmt.expr/1, expr.comma/1]. This permits dereferencing an incomplete type
in a void context. The C++ standard does not define what an `access' to an
object is, but there is reason to believe that it is the lvalue to rvalue
conversion -- if it were not, `*&*p = 1' would violate [expr]/4 in that it
accesses `*p' not to calculate the value to be stored. But, dcl.type.cv/8
indicates that volatile semantics should be the same between C and C++
where ever possible. C leaves it implementation defined as to what
constitutes an access to a volatile. So, we interpret `*vp' as a read of
the volatile object `vp' points to, unless that is an incomplete type. For
volatile references we do not do this interpretation, because that would
make it impossible to ignore the reference return value from functions. We
issue warnings in the confusing cases.
The IMPLICIT is ICV_CAST when the user is explicitly converting an expression
to void via a cast. If an expression is being implicitly converted, IMPLICIT
indicates the context of the implicit conversion. */
tree
convert_to_void (tree expr, impl_conv_void implicit, tsubst_flags_t complain)
{
location_t loc = EXPR_LOC_OR_HERE (expr);
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_at (loc, "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 = ((op1 && TREE_SIDE_EFFECTS (op1))
|| TREE_SIDE_EFFECTS (op2));
tree new_op1, new_op2;
new_op1 = NULL_TREE;
if (implicit != ICV_CAST && !side_effects)
{
if (op1)
new_op1 = convert_to_void (op1, ICV_SECOND_OF_COND, complain);
new_op2 = convert_to_void (op2, ICV_THIRD_OF_COND, complain);
}
else
{
if (op1)
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_op2),
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);