| /* Language-level data type conversion for GNU C++. |
| Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, |
| 1999, 2000, 2001, 2002, 2003 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, 59 Temple Place - Suite 330, |
| Boston, MA 02111-1307, 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" |
| |
| static tree cp_convert_to_pointer (tree, tree, bool); |
| static tree convert_to_pointer_force (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 (IS_AGGR_TYPE (intype)) |
| { |
| intype = complete_type (intype); |
| if (!COMPLETE_TYPE_P (intype)) |
| { |
| error ("can't convert from incomplete type `%T' to `%T'", |
| intype, type); |
| return error_mark_node; |
| } |
| |
| rval = build_type_conversion (type, expr); |
| if (rval) |
| { |
| if (rval == error_mark_node) |
| error ("conversion of `%E' from `%T' to `%T' 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)))) |
| { |
| /* Allow an implicit this pointer for pointer to member |
| functions. */ |
| if (TYPE_PTRMEMFUNC_P (intype)) |
| { |
| if (pedantic || warn_pmf2ptr) |
| pedwarn ("converting from `%T' to `%T'", intype, type); |
| if (TREE_CODE (expr) == PTRMEM_CST) |
| expr = build_address (PTRMEM_CST_MEMBER (expr)); |
| else |
| { |
| tree decl = maybe_dummy_object (TYPE_PTRMEM_CLASS_TYPE (intype), |
| 0); |
| decl = build_address (decl); |
| expr = get_member_function_from_ptrfunc (&decl, expr); |
| } |
| } |
| else if (TREE_CODE (TREE_TYPE (expr)) == METHOD_TYPE) |
| { |
| if (pedantic || warn_pmf2ptr) |
| pedwarn ("converting from `%T' to `%T'", intype, type); |
| expr = build_addr_func (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 `%E' from type `%T' to type `%T'", |
| 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 ("pointer to member cast from `%T' to `%T' is via virtual base", |
| intype, type); |
| else |
| { |
| error ("pointer to member cast from `%T' to `%T' 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); |
| 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 `%E' from type `%T' to type `%T'", |
| 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); |
| |
| if (TYPE_PTRMEM_P (type)) |
| /* A NULL pointer-to-member is represented by -1, not by |
| zero. */ |
| expr = build_int_2 (-1, -1); |
| else |
| expr = build_int_2 (0, 0); |
| TREE_TYPE (expr) = type; |
| /* Fix up the representation of -1 if appropriate. */ |
| force_fit_type (expr, 0); |
| return expr; |
| } |
| else if (TYPE_PTR_TO_MEMBER_P (type) && INTEGRAL_CODE_P (form)) |
| { |
| error ("invalid conversion from '%T' to '%T'", 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. */ |
| if (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr))) |
| != GET_MODE_SIZE (TYPE_MODE (type))) |
| /* There is supposed to be some integral type |
| that is the same width as a pointer. */ |
| abort (); |
| return convert_to_pointer (type, expr); |
| } |
| |
| if (type_unknown_p (expr)) |
| return instantiate_type (type, expr, tf_error | tf_warning); |
| |
| error ("cannot convert `%E' from type `%T' to type `%T'", |
| 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_ignore, NULL); |
| if (!binfo) |
| { |
| binfo = lookup_base (TREE_TYPE (type), TREE_TYPE (intype), |
| ba_ignore, 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); |
| |
| my_friendly_assert (TREE_CODE (type) == REFERENCE_TYPE, 187); |
| |
| 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, 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 `%#T' from rvalue of type `%T'"; |
| else if (CP_TYPE_VOLATILE_P (ttl)) |
| msg = "conversion to volatile reference type `%#T' from rvalue of type `%T'"; |
| else if (decl) |
| msg = "initialization of non-const reference type `%#T' from rvalue of type `%T'"; |
| else |
| msg = "conversion to non-const reference type `%#T' from rvalue of type `%T'"; |
| |
| 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_error | tf_warning : tf_none); |
| else |
| expr = convert_from_reference (expr); |
| |
| if (expr == error_mark_node) |
| return error_mark_node; |
| |
| intype = TREE_TYPE (expr); |
| |
| my_friendly_assert (TREE_CODE (intype) != REFERENCE_TYPE, 364); |
| |
| 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 `%T' to `%T' 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 ("casting `%T' to `%T' 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 `%T' to type `%T'", intype, reftype); |
| |
| if (flags & LOOKUP_SPECULATIVELY) |
| return NULL_TREE; |
| |
| 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) |
| return build_indirect_ref (val, NULL); |
| return val; |
| } |
| |
| /* Implicitly convert the lvalue EXPR to another lvalue of type TOTYPE, |
| preserving cv-qualification. */ |
| |
| tree |
| convert_lvalue (tree totype, tree expr) |
| { |
| totype = cp_build_qualified_type (totype, TYPE_QUALS (TREE_TYPE (expr))); |
| totype = build_reference_type (totype); |
| expr = convert_to_reference (totype, expr, CONV_IMPLICIT, LOOKUP_NORMAL, |
| NULL_TREE); |
| return convert_from_reference (expr); |
| } |
| |
| /* Really perform an lvalue-to-rvalue conversion, including copying an |
| argument of class type into a temporary. */ |
| |
| tree |
| force_rvalue (tree expr) |
| { |
| if (IS_AGGR_TYPE (TREE_TYPE (expr)) && TREE_CODE (expr) != TARGET_EXPR) |
| expr = ocp_convert (TREE_TYPE (expr), expr, |
| CONV_IMPLICIT|CONV_FORCE_TEMP, LOOKUP_NORMAL); |
| 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); |
| } |
| |
| /* 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); |
| |
| if (error_operand_p (e) || type == error_mark_node) |
| return error_mark_node; |
| |
| complete_type (type); |
| complete_type (TREE_TYPE (expr)); |
| |
| e = decl_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 (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. */ |
| if (!same_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (e)), |
| TYPE_MAIN_VARIANT (type))) |
| abort (); |
| TREE_TYPE (e) = TREE_TYPE (TARGET_EXPR_SLOT (e)) = type; |
| return e; |
| } |
| else if (TREE_ADDRESSABLE (type)) |
| /* We shouldn't be treating objects of ADDRESSABLE type as rvalues. */ |
| abort (); |
| else |
| return fold (build1 (NOP_EXPR, 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 |
| && ((ARITHMETIC_TYPE_P (intype) && ! (convtype & CONV_STATIC)) |
| || (TREE_CODE (intype) == POINTER_TYPE))) |
| { |
| pedwarn ("conversion from `%#T' to `%#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 ("`%#T' used where a `%T' was expected", intype, type); |
| if (flags & LOOKUP_SPECULATIVELY) |
| return NULL_TREE; |
| return error_mark_node; |
| } |
| if (code == BOOLEAN_TYPE) |
| return cp_truthvalue_conversion (e); |
| |
| return fold (convert_to_integer (type, e)); |
| } |
| if (POINTER_TYPE_P (type) || TYPE_PTR_TO_MEMBER_P (type)) |
| return fold (cp_convert_to_pointer (type, e, false)); |
| if (code == VECTOR_TYPE) |
| return fold (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 ("`%#T' used where a floating point value was expected", |
| TREE_TYPE (e)); |
| } |
| if (code == REAL_TYPE) |
| return fold (convert_to_real (type, e)); |
| else if (code == COMPLEX_TYPE) |
| return fold (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_BINFO (type), flags); |
| if (ctor) |
| return build_cplus_new (type, ctor); |
| } |
| |
| if (flags & LOOKUP_COMPLAIN) |
| error ("conversion from `%T' to non-scalar type `%T' requested", |
| TREE_TYPE (expr), type); |
| if (flags & LOOKUP_SPECULATIVELY) |
| return NULL_TREE; |
| 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 (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 = build (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_UNUSED_WARNING (expr) |
| ? "right-hand operand of comma" : NULL)); |
| |
| if (new_op1 != op1) |
| { |
| tree t = build (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)); |
| |
| if (is_volatile && !is_complete) |
| warning ("object of incomplete type `%T' will not be accessed in %s", |
| type, implicit ? implicit : "void context"); |
| else if (is_reference && is_volatile) |
| warning ("object of type `%T' will not be accessed in %s", |
| TREE_TYPE (TREE_OPERAND (expr, 0)), |
| implicit ? implicit : "void context"); |
| if (is_reference || !is_volatile || !is_complete) |
| 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 ("object `%E' of incomplete type `%T' will not be accessed in %s", |
| expr, type, implicit ? implicit : "void context"); |
| 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 ("%s is a reference, not call, to function `%E'", |
| implicit, expr); |
| } |
| |
| if (expr != error_mark_node && !VOID_TYPE_P (TREE_TYPE (expr))) |
| { |
| if (implicit && !TREE_SIDE_EFFECTS (expr) && warn_unused_value) |
| warning ("%s has no effect", implicit); |
| expr = build1 (CONVERT_EXPR, void_type_node, expr); |
| } |
| 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)) |
| { |
| expr = decl_constant_value (expr); |
| return fold (build1 (NOP_EXPR, 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 (convert_to_reference (type, e, CONV_C_CAST, LOOKUP_COMPLAIN, |
| NULL_TREE)); |
| else if (TREE_CODE (TREE_TYPE (e)) == REFERENCE_TYPE) |
| e = convert_from_reference (e); |
| |
| if (code == POINTER_TYPE) |
| return fold (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); |
| } |
| |
| 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) */ |
| |
| 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 ("converting NULL to non-pointer type"); |
| |
| expr = convert_from_reference (expr); |
| 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; |
| 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; |
| |
| default: |
| break; |
| } |
| |
| if (win) |
| { |
| if (winner) |
| { |
| if (complain) |
| { |
| error ("ambiguous default type conversion from `%T'", |
| basetype); |
| error (" candidate conversions include `%D' and `%D'", |
| 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 (TREE_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 (TREE_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 (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; |
| } |