diff options
Diffstat (limited to 'gcc-4.2.1-5666.3/gcc/cp/cvt.c')
| -rw-r--r-- | gcc-4.2.1-5666.3/gcc/cp/cvt.c | 1325 |
1 files changed, 1325 insertions, 0 deletions
diff --git a/gcc-4.2.1-5666.3/gcc/cp/cvt.c b/gcc-4.2.1-5666.3/gcc/cp/cvt.c new file mode 100644 index 000000000..425a8ce94 --- /dev/null +++ b/gcc-4.2.1-5666.3/gcc/cp/cvt.c @@ -0,0 +1,1325 @@ +/* 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 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 2, 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 COPYING. If not, write to +the Free Software Foundation, 51 Franklin Street, Fifth Floor, +Boston, MA 02110-1301, USA. */ + + +/* 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 "convert.h" +#include "toplev.h" +#include "decl.h" +#include "target.h" + +static tree cp_convert_to_pointer (tree, tree, bool); +static tree convert_to_pointer_force (tree, tree); +static tree build_type_conversion (tree, tree); +static tree build_up_reference (tree, tree, int, tree); +static void warn_ref_binding (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. If FORCE is true then allow + conversions via virtual bases (these are permitted by reinterpret_cast, + but not static_cast). */ + +static tree +cp_convert_to_pointer (tree type, tree expr, bool force) +{ + tree intype = TREE_TYPE (expr); + enum tree_code form; + tree rval; + if (intype == error_mark_node) + return error_mark_node; + + if (IS_AGGR_TYPE (intype)) + { + intype = complete_type (intype); + if (!COMPLETE_TYPE_P (intype)) + { + error ("can't convert from incomplete type %qT to %qT", + intype, type); + return error_mark_node; + } + + rval = build_type_conversion (type, expr); + if (rval) + { + if (rval == error_mark_node) + error ("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); + 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 + && IS_AGGR_TYPE (TREE_TYPE (type)) + && IS_AGGR_TYPE (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); + /* Add any qualifier conversions. */ + return build_nop (type, expr); + } + } + + if (TYPE_PTRMEMFUNC_P (type)) + { + error ("cannot convert %qE from type %qT to type %qT", + expr, intype, type); + return error_mark_node; + } + + return build_nop (type, expr); + } + else if (TYPE_PTRMEM_P (type) && TYPE_PTRMEM_P (intype)) + { + tree b1; + tree b2; + tree binfo; + enum tree_code code = PLUS_EXPR; + base_kind bk; + + b1 = TYPE_PTRMEM_CLASS_TYPE (type); + b2 = TYPE_PTRMEM_CLASS_TYPE (intype); + binfo = lookup_base (b1, b2, ba_check, &bk); + if (!binfo) + { + binfo = lookup_base (b2, b1, ba_check, &bk); + code = MINUS_EXPR; + } + if (binfo == error_mark_node) + return error_mark_node; + + if (bk == bk_via_virtual) + { + if (force) + warning (0, "pointer to member cast from %qT to %qT is via" + " virtual base", intype, type); + else + { + error ("pointer to member cast from %qT to %qT is" + " via virtual base", intype, type); + return error_mark_node; + } + /* This is a reinterpret cast, whose result is unspecified. + We choose to do nothing. */ + return build1 (NOP_EXPR, type, expr); + } + + if (TREE_CODE (expr) == PTRMEM_CST) + expr = cplus_expand_constant (expr); + + if (binfo && !integer_zerop (BINFO_OFFSET (binfo))) + expr = size_binop (code, + build_nop (sizetype, expr), + BINFO_OFFSET (binfo)); + return build_nop (type, expr); + } + else if (TYPE_PTRMEMFUNC_P (type) && TYPE_PTRMEMFUNC_P (intype)) + return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0, + /*c_cast_p=*/false); + 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), + force); + else if (TREE_CODE (expr) == OFFSET_REF) + { + tree object = TREE_OPERAND (expr, 0); + return get_member_function_from_ptrfunc (&object, + TREE_OPERAND (expr, 1)); + } + } + error ("cannot convert %qE from type %qT to type %qT", + expr, intype, type); + return error_mark_node; + } + + if (integer_zerop (expr)) + { + if (TYPE_PTRMEMFUNC_P (type)) + return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0, + /*c_cast_p=*/false); + + if (TYPE_PTRMEM_P (type)) + { + /* A NULL pointer-to-member is represented by -1, not by + zero. */ + expr = build_int_cst (type, -1); + /* Fix up the representation of -1 if appropriate. */ + expr = force_fit_type (expr, 0, false, false); + } + else + expr = build_int_cst (type, 0); + + return expr; + } + else if (TYPE_PTR_TO_MEMBER_P (type) && INTEGRAL_CODE_P (form)) + { + error ("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); + /* 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, tf_warning_or_error); + + error ("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) +{ + 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 + && IS_AGGR_TYPE (TREE_TYPE (type)) + && IS_AGGR_TYPE (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); + 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, true); +} + +/* 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) +{ + 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, TREE_TYPE (arg)); + + /* 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 = build_unary_op (ADDR_EXPR, arg, 1); + if (rval == error_mark_node) + return error_mark_node; + + if ((flags & LOOKUP_PROTECT) + && TYPE_MAIN_VARIANT (argtype) != TYPE_MAIN_VARIANT (target_type) + && IS_AGGR_TYPE (argtype) + && IS_AGGR_TYPE (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); + } + else + rval + = convert_to_pointer_force (build_pointer_type (target_type), rval); + 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 (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 = "initialization of volatile reference type %q#T from" + " rvalue of type %qT"; + else if (CP_TYPE_VOLATILE_P (ttl)) + msg = "conversion to volatile reference type %q#T " + " from rvalue of type %qT"; + else if (decl) + msg = "initialization of non-const reference type %q#T from" + " rvalue of type %qT"; + else + msg = "conversion to non-const reference type %q#T from" + " rvalue of type %qT"; + + pedwarn (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) +{ + 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; + + if (TREE_CODE (type) == FUNCTION_TYPE + && TREE_TYPE (expr) == unknown_type_node) + expr = instantiate_type (type, expr, + (flags & LOOKUP_COMPLAIN) + ? tf_warning_or_error : tf_none); + + 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); + if (!can_convert_intype_to_type + && (convtype & CONV_IMPLICIT) && IS_AGGR_TYPE (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)) + || ((convtype & CONV_IMPLICIT) && can_convert_intype_to_type)) + { + if (flags & LOOKUP_COMPLAIN) + { + tree ttl = TREE_TYPE (reftype); + tree ttr = lvalue_type (expr); + + if (! real_lvalue_p (expr)) + warn_ref_binding (reftype, intype, decl); + + if (! (convtype & CONV_CONST) + && !at_least_as_qualified_p (ttl, ttr)) + pedwarn ("conversion from %qT to %qT discards qualifiers", + ttr, reftype); + } + + return build_up_reference (reftype, expr, flags, decl); + } + 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 (TREE_CODE (intype) == POINTER_TYPE + && (comptypes (TREE_TYPE (intype), type, + COMPARE_BASE | COMPARE_DERIVED))) + warning (0, "casting %qT to %qT does not dereference pointer", + intype, reftype); + + rval = build_unary_op (ADDR_EXPR, expr, 0); + if (rval != error_mark_node) + rval = convert_force (build_pointer_type (TREE_TYPE (reftype)), + rval, 0); + if (rval != error_mark_node) + rval = build1 (NOP_EXPR, reftype, rval); + } + else + { + rval = convert_for_initialization (NULL_TREE, type, expr, flags, + "converting", 0, 0); + if (rval == NULL_TREE || rval == error_mark_node) + return rval; + warn_ref_binding (reftype, intype, decl); + rval = build_up_reference (reftype, rval, flags, decl); + } + + if (rval) + { + /* If we found a way to convert earlier, then use it. */ + return rval; + } + + if (flags & LOOKUP_COMPLAIN) + error ("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_CODE (TREE_TYPE (val)) == REFERENCE_TYPE) + { + tree t = canonical_type_variant (TREE_TYPE (TREE_TYPE (val))); + tree ref = build1 (INDIRECT_REF, t, 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)); + REFERENCE_REF_P (ref) = 1; + 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) +{ + /* APPLE LOCAL begin radar 6936421 */ + if (IS_AGGR_TYPE (TREE_TYPE (expr)) && TREE_CODE (expr) != TARGET_EXPR) { + if (objc_property_reference_expr (expr)) + expr = objc_build_property_getter_func_call (expr); + expr = ocp_convert (TREE_TYPE (expr), expr, + CONV_IMPLICIT|CONV_FORCE_TEMP, LOOKUP_NORMAL); + } + /* APPLE LOCAL end radar 6936421 */ + else + expr = decay_conversion (expr); + + return expr; +} + +/* C++ conversions, preference to static cast conversions. */ + +tree +cp_convert (tree type, tree expr) +{ + return ocp_convert (type, expr, CONV_OLD_CONVERT, LOOKUP_NORMAL); +} + +/* APPLE LOCAL begin mainline */ +/* 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) +{ + tree result; + + if (TREE_TYPE (expr) == type) + return expr; + + result = cp_convert (type, expr); + + if (!skip_evaluation && !TREE_OVERFLOW_P (expr) && result != error_mark_node) + warnings_for_convert_and_check (type, expr, result); + + return result; +} + +/* APPLE LOCAL end mainline */ +/* Conversion... + + FLAGS indicates how we should behave. */ + +tree +ocp_convert (tree type, tree expr, int convtype, int flags) +{ + tree e = expr; + enum tree_code code = TREE_CODE (type); + const char *invalid_conv_diag; + + 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))) + { + /* APPLE LOCAL default to Wformat-security 5764921 */ + error (invalid_conv_diag, ""); + return error_mark_node; + } + + e = integral_constant_value (e); + + if (IS_AGGR_TYPE (type) && (convtype & CONV_FORCE_TEMP) + /* Some internal structures (vtable_entry_type, sigtbl_ptr_type) + don't go through finish_struct, so they don't have the synthesized + constructors. So don't force a temporary. */ + && TYPE_HAS_CONSTRUCTOR (type)) + /* We need a new temporary; don't take this shortcut. */; + else if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (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. Only allow this for cv-qual changes, + though. */ + gcc_assert (same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (e)), + TYPE_MAIN_VARIANT (type))); + 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)); + } + } + + if (code == VOID_TYPE && (convtype & CONV_STATIC)) + { + e = convert_to_void (e, /*implicit=*/NULL); + return e; + } + + if (INTEGRAL_CODE_P (code)) + { + tree intype = TREE_TYPE (e); + /* enum = enum, enum = int, enum = float, (enum)pointer are all + errors. */ + if (TREE_CODE (type) == ENUMERAL_TYPE + && (((INTEGRAL_OR_ENUMERATION_TYPE_P (intype) + || TREE_CODE (intype) == REAL_TYPE) + && ! (convtype & CONV_STATIC)) + || TREE_CODE (intype) == POINTER_TYPE)) + { + if (flags & LOOKUP_COMPLAIN) + pedwarn ("conversion from %q#T to %q#T", intype, type); + + if (flag_pedantic_errors) + return error_mark_node; + } + if (IS_AGGR_TYPE (intype)) + { + tree rval; + rval = build_type_conversion (type, e); + if (rval) + return rval; + if (flags & LOOKUP_COMPLAIN) + error ("%q#T used where a %qT was expected", intype, type); + return error_mark_node; + } + if (code == BOOLEAN_TYPE) + return cp_truthvalue_conversion (e); + + return fold_if_not_in_template (convert_to_integer (type, e)); + } + if (POINTER_TYPE_P (type) || TYPE_PTR_TO_MEMBER_P (type)) + return fold_if_not_in_template (cp_convert_to_pointer (type, e, false)); + if (code == VECTOR_TYPE) + { + tree in_vtype = TREE_TYPE (e); + if (IS_AGGR_TYPE (in_vtype)) + { + tree ret_val; + ret_val = build_type_conversion (type, e); + if (ret_val) + return ret_val; + if (flags & LOOKUP_COMPLAIN) + error ("%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 (IS_AGGR_TYPE (TREE_TYPE (e))) + { + tree rval; + rval = build_type_conversion (type, e); + if (rval) + return rval; + else + if (flags & LOOKUP_COMPLAIN) + error ("%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 (IS_AGGR_TYPE_CODE (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 ((flags & LOOKUP_ONLYCONVERTING) + && ! (IS_AGGR_TYPE (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); + else + ctor = build_special_member_call (NULL_TREE, + complete_ctor_identifier, + build_tree_list (NULL_TREE, ctor), + type, flags); + if (ctor) + return build_cplus_new (type, ctor); + } + + if (flags & LOOKUP_COMPLAIN) + error ("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. + + IMPLICIT is tells us the context of an implicit void conversion. */ + +tree +convert_to_void (tree expr, const char *implicit) +{ + 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)) + return error_mark_node; + if (TREE_CODE (expr) == PSEUDO_DTOR_EXPR) + { + 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)); + tree new_op2 = convert_to_void + (op2, (implicit && !TREE_SIDE_EFFECTS (op1) + ? "third operand of conditional" : NULL)); + + 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)); + + 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) + 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))) + 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) + 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 = TREE_OPERAND (init, 0); + expr = build3 (CALL_EXPR, TREE_TYPE (TREE_TYPE (TREE_TYPE (fn))), + fn, TREE_OPERAND (init, 1), NULL_TREE); + } + } + 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. */ + pedwarn ("%s cannot resolve address of overloaded function", + implicit ? implicit : "void cast"); + expr = void_zero_node; + } + else if (implicit && probe == expr && is_overloaded_fn (probe)) + { + /* Only warn when there is no &. */ + 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)) + warning (OPT_Wunused_value, "%s has no effect", implicit); + else + { + tree e; + enum tree_code code; + enum tree_code_class class; + + 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); + class = TREE_CODE_CLASS (code); + if (class == tcc_comparison + || class == tcc_unary + || (class == tcc_binary + && !(code == MODIFY_EXPR + || code == INIT_EXPR + || code == PREDECREMENT_EXPR + || code == PREINCREMENT_EXPR + || code == POSTDECREMENT_EXPR + || code == POSTINCREMENT_EXPR))) + warning (OPT_Wunused_value, "value computed is not used"); + } + } + expr = build1 (CONVERT_EXPR, void_type_node, expr); + } + /* APPLE LOCAL Altivec 4869813 */ + if (! targetm.cast_expr_as_vector_init) + if (! TREE_SIDE_EFFECTS (expr)) + expr = void_zero_node; + return expr; +} + +/* Create an expression whose value is that of EXPR, + converted to type TYPE. The TREE_TYPE of the value + is always TYPE. This function implements all reasonable + conversions; callers should filter out those that are + not permitted by the language being compiled. + + Most of this routine is from build_reinterpret_cast. + + The backend cannot call cp_convert (what was convert) because + conversions to/from basetypes may involve memory references + (vbases) and adding or subtracting small values (multiple + inheritance), but it calls convert from the constant folding code + on subtrees of already built trees after it has ripped them apart. + + Also, if we ever support range variables, we'll probably also have to + do a little bit more work. */ + +tree +convert (tree type, tree expr) +{ + tree intype; + + if (type == error_mark_node || expr == error_mark_node) + return error_mark_node; + + intype = TREE_TYPE (expr); + + if (POINTER_TYPE_P (type) && POINTER_TYPE_P (intype)) + return fold_if_not_in_template (build_nop (type, expr)); + + return ocp_convert (type, expr, CONV_OLD_CONVERT, + LOOKUP_NORMAL|LOOKUP_NO_CONVERSION); +} + +/* Like cp_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). */ + +tree +convert_force (tree type, tree expr, int convtype) +{ + tree e = expr; + enum tree_code code = TREE_CODE (type); + + if (code == REFERENCE_TYPE) + return (fold_if_not_in_template + (convert_to_reference (type, e, CONV_C_CAST, LOOKUP_COMPLAIN, + NULL_TREE))); + + if (code == POINTER_TYPE) + return fold_if_not_in_template (convert_to_pointer_force (type, e)); + + /* From typeck.c convert_for_assignment */ + if (((TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE && TREE_CODE (e) == ADDR_EXPR + && TREE_CODE (TREE_TYPE (e)) == POINTER_TYPE + && TREE_CODE (TREE_TYPE (TREE_TYPE (e))) == METHOD_TYPE) + || integer_zerop (e) + || TYPE_PTRMEMFUNC_P (TREE_TYPE (e))) + && TYPE_PTRMEMFUNC_P (type)) + /* compatible pointer to member functions. */ + return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), e, 1, + /*c_cast_p=*/1); + + return ocp_convert (type, e, CONV_C_CAST|convtype, LOOKUP_NORMAL); +} + +/* Convert an aggregate EXPR to type XTYPE. If a conversion + exists, return the attempted conversion. This may + return ERROR_MARK_NODE if the conversion is not + allowed (references private members, etc). + If no conversion exists, NULL_TREE is returned. + + FIXME: Ambiguity checking is wrong. Should choose one by the implicit + object parameter, or by the second standard conversion sequence if + that doesn't do it. This will probably wait for an overloading rewrite. + (jason 8/9/95) */ + +static tree +build_type_conversion (tree xtype, tree expr) +{ + /* C++: check to see if we can convert this aggregate type + into the required type. */ + return build_user_type_conversion (xtype, expr, LOOKUP_NORMAL); +} + +/* Convert the given EXPR to one of a group of types suitable for use in an + expression. DESIRES is a combination of various WANT_* flags (q.v.) + which indicates which types are suitable. If COMPLAIN is true, complain + about ambiguity; otherwise, the caller will deal with it. */ + +tree +build_expr_type_conversion (int desires, tree expr, bool complain) +{ + tree basetype = TREE_TYPE (expr); + tree conv = NULL_TREE; + tree winner = NULL_TREE; + + if (expr == null_node + && (desires & WANT_INT) + && !(desires & WANT_NULL)) + warning (OPT_Wconversion, "converting NULL to non-pointer type"); + + basetype = TREE_TYPE (expr); + + if (basetype == error_mark_node) + return error_mark_node; + + if (! IS_AGGR_TYPE (basetype)) + switch (TREE_CODE (basetype)) + { + case INTEGER_TYPE: + if ((desires & WANT_NULL) && null_ptr_cst_p (expr)) + return expr; + /* else fall through... */ + + case BOOLEAN_TYPE: + return (desires & WANT_INT) ? expr : NULL_TREE; + case ENUMERAL_TYPE: + return (desires & WANT_ENUM) ? expr : NULL_TREE; + case REAL_TYPE: + return (desires & WANT_FLOAT) ? expr : NULL_TREE; + case POINTER_TYPE: + return (desires & WANT_POINTER) ? expr : NULL_TREE; + + case FUNCTION_TYPE: + case ARRAY_TYPE: + return (desires & WANT_POINTER) ? decay_conversion (expr) + : NULL_TREE; + + case VECTOR_TYPE: + if ((desires & WANT_VECTOR) == 0) + return NULL_TREE; + switch (TREE_CODE (TREE_TYPE (basetype))) + { + case INTEGER_TYPE: + case BOOLEAN_TYPE: + return (desires & WANT_INT) ? expr : NULL_TREE; + case ENUMERAL_TYPE: + return (desires & WANT_ENUM) ? expr : NULL_TREE; + case REAL_TYPE: + return (desires & WANT_FLOAT) ? expr : NULL_TREE; + default: + return NULL_TREE; + } + + default: + return NULL_TREE; + } + + /* The code for conversions from class type is currently only used for + delete expressions. Other expressions are handled by build_new_op. */ + if (!complete_type_or_else (basetype, expr)) + return error_mark_node; + if (!TYPE_HAS_CONVERSION (basetype)) + return NULL_TREE; + + for (conv = lookup_conversions (basetype); conv; conv = TREE_CHAIN (conv)) + { + int win = 0; + tree candidate; + tree cand = TREE_VALUE (conv); + + if (winner && winner == cand) + continue; + + candidate = non_reference (TREE_TYPE (TREE_TYPE (cand))); + + switch (TREE_CODE (candidate)) + { + case BOOLEAN_TYPE: + case INTEGER_TYPE: + win = (desires & WANT_INT); break; + case ENUMERAL_TYPE: + win = (desires & WANT_ENUM); break; + case REAL_TYPE: + win = (desires & WANT_FLOAT); break; + case POINTER_TYPE: + win = (desires & WANT_POINTER); break; + + case VECTOR_TYPE: + if ((desires & WANT_VECTOR) == 0) + break; + switch (TREE_CODE (TREE_TYPE (candidate))) + { + case BOOLEAN_TYPE: + case INTEGER_TYPE: + win = (desires & WANT_INT); break; + case ENUMERAL_TYPE: + win = (desires & WANT_ENUM); break; + case REAL_TYPE: + win = (desires & WANT_FLOAT); break; + default: + break; + } + break; + + default: + break; + } + + if (win) + { + if (winner) + { + if (complain) + { + error ("ambiguous default type conversion from %qT", + basetype); + error (" candidate conversions include %qD and %qD", + winner, cand); + } + return error_mark_node; + } + else + winner = cand; + } + } + + if (winner) + { + tree type = non_reference (TREE_TYPE (TREE_TYPE (winner))); + return build_user_type_conversion (type, expr, LOOKUP_NORMAL); + } + + return NULL_TREE; +} + +/* Implements integral promotion (4.1) and float->double promotion. */ + +tree +type_promotes_to (tree type) +{ + if (type == error_mark_node) + return error_mark_node; + + type = TYPE_MAIN_VARIANT (type); + + /* bool always promotes to int (not unsigned), even if it's the same + size. */ + if (type == boolean_type_node) + type = integer_type_node; + + /* Normally convert enums to int, but convert wide enums to something + wider. */ + else if (TREE_CODE (type) == ENUMERAL_TYPE + || type == wchar_type_node) + { + int precision = MAX (TYPE_PRECISION (type), + TYPE_PRECISION (integer_type_node)); + tree totype = c_common_type_for_size (precision, 0); + if (TYPE_UNSIGNED (type) + && ! int_fits_type_p (TYPE_MAX_VALUE (type), totype)) + type = c_common_type_for_size (precision, 1); + else + type = totype; + } + else if (c_promoting_integer_type_p (type)) + { + /* Retain unsignedness if really not getting bigger. */ + if (TYPE_UNSIGNED (type) + && TYPE_PRECISION (type) == TYPE_PRECISION (integer_type_node)) + type = unsigned_type_node; + else + type = integer_type_node; + } + else if (type == float_type_node) + type = double_type_node; + + return type; +} + +/* The routines below this point are carefully written to conform to + the standard. They use the same terminology, and follow the rules + closely. Although they are used only in pt.c at the moment, they + should presumably be used everywhere in the future. */ + +/* Attempt to perform qualification conversions on EXPR to convert it + to TYPE. Return the resulting expression, or error_mark_node if + the conversion was impossible. */ + +tree +perform_qualification_conversions (tree type, tree expr) +{ + tree expr_type; + + expr_type = TREE_TYPE (expr); + + if (same_type_p (type, expr_type)) + return expr; + else if (TYPE_PTR_P (type) && TYPE_PTR_P (expr_type) + && comp_ptr_ttypes (TREE_TYPE (type), TREE_TYPE (expr_type))) + return build_nop (type, expr); + else if (TYPE_PTR_TO_MEMBER_P (type) + && TYPE_PTR_TO_MEMBER_P (expr_type) + && same_type_p (TYPE_PTRMEM_CLASS_TYPE (type), + TYPE_PTRMEM_CLASS_TYPE (expr_type)) + && comp_ptr_ttypes (TYPE_PTRMEM_POINTED_TO_TYPE (type), + TYPE_PTRMEM_POINTED_TO_TYPE (expr_type))) + return build_nop (type, expr); + else + return error_mark_node; +} |