| 1 | /* Variables and structures for overloading rules. |
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| 2 | Copyright (C) 1993 Free Software Foundation, Inc. |
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| 3 | |
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| 4 | This file is part of GNU CC. |
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| 5 | |
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| 6 | GNU CC is free software; you can redistribute it and/or modify |
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| 7 | it under the terms of the GNU General Public License as published by |
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| 8 | the Free Software Foundation; either version 2, or (at your option) |
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| 9 | any later version. |
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| 10 | |
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| 11 | GNU CC is distributed in the hope that it will be useful, |
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 14 | GNU General Public License for more details. |
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| 15 | |
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| 16 | You should have received a copy of the GNU General Public License |
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| 17 | along with GNU CC; see the file COPYING. If not, write to |
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| 18 | the Free Software Foundation, 59 Temple Place - Suite 330, |
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| 19 | Boston, MA 02111-1307, USA. */ |
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| 20 | |
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| 21 | /* The following structure is used when comparing various alternatives |
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| 22 | for overloading. The unsigned quantity `strikes.i' is used |
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| 23 | for fast comparison of two possibilities. This number is an |
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| 24 | aggregate of four constituents: |
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| 25 | |
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| 26 | EVIL: if this is non-zero, then the candidate should not be considered |
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| 27 | ELLIPSIS: if this is non-zero, then some actual argument has been matched |
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| 28 | against an ellipsis |
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| 29 | USER: if this is non-zero, then a user-defined type conversion is needed |
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| 30 | B_OR_D: if this is non-zero, then use a base pointer instead of the |
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| 31 | type of the pointer we started with. |
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| 32 | EASY: if this is non-zero, then we have a builtin conversion |
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| 33 | (such as int to long, int to float, etc) to do. |
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| 34 | |
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| 35 | If two candidates require user-defined type conversions, and the |
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| 36 | type conversions are not identical, then an ambiguity error |
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| 37 | is reported. |
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| 38 | |
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| 39 | If two candidates agree on user-defined type conversions, |
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| 40 | and one uses pointers of strictly higher type (derived where |
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| 41 | another uses base), then that alternative is silently chosen. |
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| 42 | |
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| 43 | Note that this technique really only works for 255 arguments. Perhaps |
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| 44 | this is not enough. */ |
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| 45 | |
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| 46 | /* These macros and harshness_code are used by the NEW METHOD. */ |
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| 47 | #define EVIL_CODE (1<<7) |
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| 48 | #define CONST_CODE (1<<6) |
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| 49 | #define ELLIPSIS_CODE (1<<5) |
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| 50 | #define USER_CODE (1<<4) |
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| 51 | #define STD_CODE (1<<3) |
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| 52 | #define PROMO_CODE (1<<2) |
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| 53 | #define QUAL_CODE (1<<1) |
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| 54 | #define TRIVIAL_CODE (1<<0) |
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| 55 | |
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| 56 | struct harshness_code |
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| 57 | { |
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| 58 | /* What kind of conversion is involved. */ |
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| 59 | unsigned short code; |
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| 60 | |
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| 61 | /* The inheritance distance. */ |
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| 62 | short distance; |
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| 63 | |
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| 64 | /* For a PROMO_CODE, Any special penalties involved in integral conversions. |
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| 65 | This exists because $4.1 of the ARM states that something like |
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| 66 | `short unsigned int' should promote to `int', not `unsigned int'. |
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| 67 | If, for example, it tries to match two fns, f(int) and f(unsigned), |
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| 68 | f(int) should be a better match than f(unsigned) by this rule. Without |
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| 69 | this extra metric, they both only appear as "integral promotions", which |
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| 70 | will lead to an ambiguity. |
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| 71 | For a TRIVIAL_CODE, This is also used by build_overload_call_real and |
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| 72 | convert_harshness to keep track of other information we need. */ |
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| 73 | unsigned short int_penalty; |
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| 74 | }; |
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| 75 | |
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| 76 | struct candidate |
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| 77 | { |
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| 78 | struct harshness_code h; /* Used for single-argument conversions. */ |
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| 79 | |
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| 80 | int h_len; /* The length of the harshness vector. */ |
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| 81 | |
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| 82 | tree function; /* A FUNCTION_DECL */ |
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| 83 | tree basetypes; /* The path to function. */ |
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| 84 | tree arg; /* first parm to function. */ |
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| 85 | |
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| 86 | /* Indexed by argument number, encodes evil, user, d_to_b, and easy |
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| 87 | strikes for that argument. At end of array, we store the index+1 |
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| 88 | of where we started using default parameters, or 0 if there are |
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| 89 | none. */ |
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| 90 | struct harshness_code *harshness; |
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| 91 | |
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| 92 | union |
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| 93 | { |
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| 94 | tree field; /* If no evil strikes, the FUNCTION_DECL of |
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| 95 | the function (if a member function). */ |
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| 96 | int bad_arg; /* the index of the first bad argument: |
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| 97 | 0 if no bad arguments |
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| 98 | > 0 is first bad argument |
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| 99 | -1 if extra actual arguments |
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| 100 | -2 if too few actual arguments. |
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| 101 | -3 if const/non const method mismatch. |
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| 102 | -4 if type unification failed. |
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| 103 | -5 if contravariance violation. */ |
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| 104 | } u; |
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| 105 | }; |
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| 106 | int rank_for_overload (); |
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| 107 | |
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| 108 | /* Variables shared between class.c and call.c. */ |
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| 109 | |
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| 110 | extern int n_vtables; |
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| 111 | extern int n_vtable_entries; |
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| 112 | extern int n_vtable_searches; |
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| 113 | extern int n_vtable_elems; |
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| 114 | extern int n_convert_harshness; |
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| 115 | extern int n_compute_conversion_costs; |
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| 116 | extern int n_build_method_call; |
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| 117 | extern int n_inner_fields_searched; |
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