119 lines
4.0 KiB
C
119 lines
4.0 KiB
C
/* Variables and structures for overloading rules.
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Copyright (C) 1993 Free Software Foundation, Inc.
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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$Id: cp-class.h,v 1.2 1993/08/02 17:31:27 mycroft Exp $
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*/
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/* The following structure is used when comparing various alternatives
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for overloading. The unsigned quantity `strikes.i' is used
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for fast comparison of two possibilities. This number is an
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aggregate of four constituents:
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EVIL: if this is non-zero, then the candidate should not be considered
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ELLIPSIS: if this is non-zero, then some actual argument has been matched
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against an ellipsis
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USER: if this is non-zero, then a user-defined type conversion is needed
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B_OR_D: if this is non-zero, then use a base pointer instead of the
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type of the pointer we started with.
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EASY: if this is non-zero, then we have a builtin conversion
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(such as int to long, int to float, etc) to do.
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If two candidates require user-defined type conversions, and the
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type conversions are not identical, then an ambiguity error
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is reported.
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If two candidates agree on user-defined type conversions,
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and one uses pointers of strictly higher type (derived where
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another uses base), then that alternative is silently chosen.
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If two candidates have a non-monotonic derived/base pointer
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relationship, and/or a non-monotonic easy conversion relationship,
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then a warning is emitted to show which paths are possible, and
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which one is being chosen.
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For example:
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int i;
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double x;
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overload f;
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int f (int, int);
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double f (double, double);
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f (i, x); // draws a warning
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struct B
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{
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f (int);
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} *bb;
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struct D : B
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{
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f (double);
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} *dd;
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dd->f (x); // exact match
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dd->f (i); // draws warning
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Note that this technique really only works for 255 arguments. Perhaps
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this is not enough. */
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struct candidate
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{
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tree function; /* A FUNCTION_DECL */
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unsigned char evil; /* !0 if this will never convert. */
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unsigned char ellipsis; /* !0 if a match against an ellipsis occurred */
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unsigned char user; /* !0 if at least one user-defined type conv. */
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unsigned short b_or_d; /* count number of derived->base or
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base->derived conv. */
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unsigned short easy; /* count number of builtin type conv. */
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tree arg; /* first parm to function. */
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unsigned short *harshness; /* Indexed by argument number, encodes
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evil, user, d_to_b, and easy strikes for
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that argument.
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At end of array, we store the index+1
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of where we started using default
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parameters, or 0 if there are none. */
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union
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{
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tree field; /* If no evil strikes, the FUNCTION_DECL of
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the function (if a member function). */
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int bad_arg; /* the index of the first bad argument:
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0 if no bad arguments
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> 0 is first bad argument
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-1 if extra actual arguments
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-2 if too few actual arguments.
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-3 if const/non const method mismatch.
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-4 if type unification failed.
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-5 if contravariance violation. */
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} u;
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};
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int rank_for_overload ();
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/* Variables shared between cp-class.c and cp-call.c. */
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extern int n_vtables;
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extern int n_vtable_entries;
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extern int n_vtable_searches;
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extern int n_vtable_elems;
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extern int n_convert_harshness;
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extern int n_compute_conversion_costs;
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extern int n_build_method_call;
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extern int n_inner_fields_searched;
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