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