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symtab.c
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symtab.c
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/* Symbol table manager for Bison.
Copyright (C) 1984, 1989, 2000-2002, 2004-2015, 2018-2020 Free
Software Foundation, Inc.
This file is part of Bison, the GNU Compiler Compiler.
This program 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 3 of the License, or
(at your option) any later version.
This program 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 this program. If not, see <http://www.gnu.org/licenses/>. */
#include <config.h>
#include "symtab.h"
#include "system.h"
#include <assure.h>
#include <fstrcmp.h>
#include <hash.h>
#include <quote.h>
#include "complain.h"
#include "getargs.h"
#include "gram.h"
#include "intprops.h"
/** Undefined token code. */
#define CODE_UNDEFINED (-1)
/* Undefined symbol number. */
#define NUMBER_UNDEFINED (-1)
static struct hash_table *symbol_table = NULL;
static struct hash_table *semantic_type_table = NULL;
/*----------------------------------------------------------------.
| Symbols sorted by tag. Allocated by table_sort, after which no |
| more symbols should be created. |
`----------------------------------------------------------------*/
static symbol **symbols_sorted = NULL;
static semantic_type **semantic_types_sorted = NULL;
/*------------------------.
| Distinguished symbols. |
`------------------------*/
symbol *errtoken = NULL;
symbol *undeftoken = NULL;
symbol *eoftoken = NULL;
symbol *acceptsymbol = NULL;
symbol *startsymbol = NULL;
location startsymbol_loc;
/* Precedence relation graph. */
static symgraph **prec_nodes;
/* Store which associativity is used. */
static bool *used_assoc = NULL;
bool tag_seen = false;
/* Whether SYM was defined by the user. */
static bool
symbol_is_user_defined (symbol *sym)
{
const bool eof_is_user_defined
= !eoftoken->alias || STRNEQ (eoftoken->alias->tag, "$end");
return sym->tag[0] != '$'
&& (eof_is_user_defined || (sym != eoftoken && sym->alias != errtoken))
&& sym != errtoken && sym->alias != errtoken
&& sym != undeftoken && sym->alias != undeftoken;
}
/*--------------------------.
| Create a new sym_content. |
`--------------------------*/
static sym_content *
sym_content_new (symbol *s)
{
sym_content *res = xmalloc (sizeof *res);
res->symbol = s;
res->type_name = NULL;
res->type_loc = empty_loc;
for (int i = 0; i < CODE_PROPS_SIZE; ++i)
code_props_none_init (&res->props[i]);
res->number = NUMBER_UNDEFINED;
res->prec_loc = empty_loc;
res->prec = 0;
res->assoc = undef_assoc;
res->code = CODE_UNDEFINED;
res->class = unknown_sym;
res->status = undeclared;
return res;
}
/*---------------------------------.
| Create a new symbol, named TAG. |
`---------------------------------*/
static symbol *
symbol_new (uniqstr tag, location loc)
{
symbol *res = xmalloc (sizeof *res);
uniqstr_assert (tag);
/* If the tag is not a string (starts with a double quote), check
that it is valid for Yacc. */
if (tag[0] != '\"' && tag[0] != '\'' && strchr (tag, '-'))
complain (&loc, Wyacc,
_("POSIX Yacc forbids dashes in symbol names: %s"), tag);
res->tag = tag;
res->location = loc;
res->translatable = false;
res->location_of_lhs = false;
res->alias = NULL;
res->content = sym_content_new (res);
res->is_alias = false;
return res;
}
/*--------------------.
| Free a sym_content. |
`--------------------*/
static void
sym_content_free (sym_content *sym)
{
free (sym);
}
/*---------------------------------------------------------.
| Free a symbol and its associated content if appropriate. |
`---------------------------------------------------------*/
static void
symbol_free (void *ptr)
{
symbol *sym = (symbol *)ptr;
if (!sym->is_alias)
sym_content_free (sym->content);
free (sym);
}
/* If needed, swap first and second so that first has the earliest
location (according to location_cmp).
Many symbol features (e.g., token codes) are not assigned during
parsing, but in a second step, via a traversal of the symbol table
sorted on tag.
However, error messages make more sense if we keep the first
declaration first.
*/
static void
symbols_sort (const symbol **first, const symbol **second)
{
if (0 < location_cmp ((*first)->location, (*second)->location))
{
const symbol* tmp = *first;
*first = *second;
*second = tmp;
}
}
/* Likewise, for locations. */
static void
locations_sort (location *first, location *second)
{
if (0 < location_cmp (*first, *second))
{
location tmp = *first;
*first = *second;
*second = tmp;
}
}
char const *
code_props_type_string (code_props_type kind)
{
switch (kind)
{
case destructor:
return "%destructor";
case printer:
return "%printer";
}
abort ();
}
/*----------------------------------------.
| Create a new semantic type, named TAG. |
`----------------------------------------*/
static semantic_type *
semantic_type_new (uniqstr tag, const location *loc)
{
semantic_type *res = xmalloc (sizeof *res);
uniqstr_assert (tag);
res->tag = tag;
res->location = loc ? *loc : empty_loc;
res->status = undeclared;
for (int i = 0; i < CODE_PROPS_SIZE; ++i)
code_props_none_init (&res->props[i]);
return res;
}
/*-----------------.
| Print a symbol. |
`-----------------*/
#define SYMBOL_INT_ATTR_PRINT(Attr) \
if (s->content) \
fprintf (f, " %s = %d", #Attr, s->content->Attr)
#define SYMBOL_STR_ATTR_PRINT(Attr) \
if (s->content && s->content->Attr) \
fprintf (f, " %s { %s }", #Attr, s->content->Attr)
#define SYMBOL_CODE_PRINT(Attr) \
if (s->content && s->content->props[Attr].code) \
fprintf (f, " %s { %s }", #Attr, s->content->props[Attr].code)
void
symbol_print (symbol const *s, FILE *f)
{
if (s)
{
symbol_class c = s->content->class;
fprintf (f, "%s: %s",
c == unknown_sym ? "unknown"
: c == pct_type_sym ? "%type"
: c == token_sym ? "token"
: c == nterm_sym ? "nterm"
: NULL, /* abort. */
s->tag);
putc (' ', f);
location_print (s->location, f);
SYMBOL_INT_ATTR_PRINT (code);
SYMBOL_INT_ATTR_PRINT (number);
SYMBOL_STR_ATTR_PRINT (type_name);
SYMBOL_CODE_PRINT (destructor);
SYMBOL_CODE_PRINT (printer);
}
else
fputs ("<NULL>", f);
}
#undef SYMBOL_ATTR_PRINT
#undef SYMBOL_CODE_PRINT
/*----------------------------------.
| Whether S is a valid identifier. |
`----------------------------------*/
static bool
is_identifier (uniqstr s)
{
static char const alphanum[26 + 26 + 1 + 10] =
"abcdefghijklmnopqrstuvwxyz"
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"_"
"0123456789";
if (!s || ! memchr (alphanum, *s, sizeof alphanum - 10))
return false;
for (++s; *s; ++s)
if (! memchr (alphanum, *s, sizeof alphanum))
return false;
return true;
}
/*-----------------------------------------------.
| Get the identifier associated to this symbol. |
`-----------------------------------------------*/
uniqstr
symbol_id_get (symbol const *sym)
{
if (sym->alias)
sym = sym->alias;
return is_identifier (sym->tag) ? sym->tag : 0;
}
/*------------------------------------------------------------------.
| Complain that S's WHAT is redeclared at SECOND, and was first set |
| at FIRST. |
`------------------------------------------------------------------*/
static void
complain_symbol_redeclared (symbol *s, const char *what, location first,
location second)
{
locations_sort (&first, &second);
complain (&second, complaint, _("%s redeclaration for %s"), what, s->tag);
subcomplain (&first, complaint, _("previous declaration"));
}
static void
complain_semantic_type_redeclared (semantic_type *s, const char *what, location first,
location second)
{
locations_sort (&first, &second);
complain (&second, complaint, _("%s redeclaration for <%s>"), what, s->tag);
subcomplain (&first, complaint, _("previous declaration"));
}
static void
complain_class_redeclared (symbol *sym, symbol_class class, location second)
{
complain (&second, complaint,
class == token_sym
? _("symbol %s redeclared as a token")
: _("symbol %s redeclared as a nonterminal"), sym->tag);
if (!location_empty (sym->location))
subcomplain (&sym->location, complaint, _("previous definition"));
}
static const symbol *
symbol_from_uniqstr_fuzzy (const uniqstr key)
{
aver (symbols_sorted);
#define FSTRCMP_THRESHOLD 0.6
double best_similarity = FSTRCMP_THRESHOLD;
const symbol *res = NULL;
size_t count = hash_get_n_entries (symbol_table);
for (int i = 0; i < count; ++i)
{
symbol *sym = symbols_sorted[i];
if (STRNEQ (key, sym->tag)
&& (sym->content->status == declared
|| sym->content->status == undeclared))
{
double similarity = fstrcmp_bounded (key, sym->tag, best_similarity);
if (best_similarity < similarity)
{
res = sym;
best_similarity = similarity;
}
}
}
return res;
}
static void
complain_symbol_undeclared (const symbol *sym)
{
assert (sym->content->status != declared);
const symbol *best = symbol_from_uniqstr_fuzzy (sym->tag);
if (best)
{
complain (&sym->location,
sym->content->status == needed ? complaint : Wother,
_("symbol %s is used, but is not defined as a token"
" and has no rules; did you mean %s?"),
quote_n (0, sym->tag),
quote_n (1, best->tag));
if (feature_flag & feature_caret)
location_caret_suggestion (sym->location, best->tag, stderr);
}
else
complain (&sym->location,
sym->content->status == needed ? complaint : Wother,
_("symbol %s is used, but is not defined as a token"
" and has no rules"),
quote (sym->tag));
}
void
symbol_location_as_lhs_set (symbol *sym, location loc)
{
if (!sym->location_of_lhs)
{
sym->location = loc;
sym->location_of_lhs = true;
}
}
/*-----------------------------------------------------------------.
| Set the TYPE_NAME associated with SYM. Does nothing if passed 0 |
| as TYPE_NAME. |
`-----------------------------------------------------------------*/
void
symbol_type_set (symbol *sym, uniqstr type_name, location loc)
{
if (type_name)
{
tag_seen = true;
if (sym->content->type_name)
complain_symbol_redeclared (sym, "%type",
sym->content->type_loc, loc);
else
{
uniqstr_assert (type_name);
sym->content->type_name = type_name;
sym->content->type_loc = loc;
}
}
}
/*--------------------------------------------------------.
| Set the DESTRUCTOR or PRINTER associated with the SYM. |
`--------------------------------------------------------*/
void
symbol_code_props_set (symbol *sym, code_props_type kind,
code_props const *code)
{
if (sym->content->props[kind].code)
complain_symbol_redeclared (sym, code_props_type_string (kind),
sym->content->props[kind].location,
code->location);
else
sym->content->props[kind] = *code;
}
/*-----------------------------------------------------.
| Set the DESTRUCTOR or PRINTER associated with TYPE. |
`-----------------------------------------------------*/
void
semantic_type_code_props_set (semantic_type *type,
code_props_type kind,
code_props const *code)
{
if (type->props[kind].code)
complain_semantic_type_redeclared (type, code_props_type_string (kind),
type->props[kind].location,
code->location);
else
type->props[kind] = *code;
}
/*---------------------------------------------------.
| Get the computed %destructor or %printer for SYM. |
`---------------------------------------------------*/
code_props *
symbol_code_props_get (symbol *sym, code_props_type kind)
{
/* Per-symbol code props. */
if (sym->content->props[kind].code)
return &sym->content->props[kind];
/* Per-type code props. */
if (sym->content->type_name)
{
code_props *code =
&semantic_type_get (sym->content->type_name, NULL)->props[kind];
if (code->code)
return code;
}
/* Apply default code props's only to user-defined symbols. */
if (symbol_is_user_defined (sym))
{
code_props *code = &semantic_type_get (sym->content->type_name ? "*" : "",
NULL)->props[kind];
if (code->code)
return code;
}
return &code_props_none;
}
/*-----------------------------------------------------------------.
| Set the PRECEDENCE associated with SYM. Does nothing if invoked |
| with UNDEF_ASSOC as ASSOC. |
`-----------------------------------------------------------------*/
void
symbol_precedence_set (symbol *sym, int prec, assoc a, location loc)
{
if (a != undef_assoc)
{
sym_content *s = sym->content;
if (s->prec)
complain_symbol_redeclared (sym, assoc_to_string (a),
s->prec_loc, loc);
else
{
s->prec = prec;
s->assoc = a;
s->prec_loc = loc;
}
}
/* Only terminals have a precedence. */
symbol_class_set (sym, token_sym, loc, false);
}
/*------------------------------------.
| Set the CLASS associated with SYM. |
`------------------------------------*/
static void
complain_pct_type_on_token (location *loc)
{
complain (loc, Wyacc,
_("POSIX yacc reserves %%type to nonterminals"));
}
void
symbol_class_set (symbol *sym, symbol_class class, location loc, bool declaring)
{
aver (class != unknown_sym);
sym_content *s = sym->content;
if (class == pct_type_sym)
{
if (s->class == token_sym)
complain_pct_type_on_token (&loc);
else if (s->class == unknown_sym)
s->class = class;
}
else if (s->class != unknown_sym && s->class != pct_type_sym
&& s->class != class)
complain_class_redeclared (sym, class, loc);
else
{
if (class == token_sym && s->class == pct_type_sym)
complain_pct_type_on_token (&sym->location);
s->class = class;
if (declaring)
{
if (s->status == declared)
{
complain (&loc, Wother,
_("symbol %s redeclared"), sym->tag);
subcomplain (&sym->location, Wother,
_("previous declaration"));
}
else
{
sym->location = loc;
s->status = declared;
}
}
}
}
/*----------------------------.
| Set the token code of SYM. |
`----------------------------*/
void
symbol_code_set (symbol *sym, int code, location loc)
{
int *codep = &sym->content->code;
if (sym->content->class != token_sym)
complain (&loc, complaint,
_("nonterminals cannot be given a token code"));
else if (*codep != CODE_UNDEFINED
&& *codep != code)
complain (&loc, complaint, _("redefining code of token %s"),
sym->tag);
else if (code == INT_MAX)
complain (&loc, complaint, _("code of token %s too large"),
sym->tag);
else
{
*codep = code;
/* User defined $end token? */
if (code == 0 && !eoftoken)
{
eoftoken = sym->content->symbol;
eoftoken->content->number = 0;
}
}
}
/*----------------------------------------------------------.
| If SYM is not defined, report an error, and consider it a |
| nonterminal. |
`----------------------------------------------------------*/
static void
symbol_check_defined (symbol *sym)
{
sym_content *s = sym->content;
if (s->class == unknown_sym || s->class == pct_type_sym)
{
complain_symbol_undeclared (sym);
s->class = nterm_sym;
}
if (s->number == NUMBER_UNDEFINED)
s->number = s->class == token_sym ? ntokens++ : nnterms++;
if (s->class == token_sym
&& sym->tag[0] == '"'
&& !sym->is_alias)
complain (&sym->location, Wdangling_alias,
_("string literal %s not attached to a symbol"),
sym->tag);
for (int i = 0; i < 2; ++i)
symbol_code_props_get (sym, i)->is_used = true;
/* Set the semantic type status associated to the current symbol to
'declared' so that we could check semantic types unnecessary uses. */
if (s->type_name)
{
semantic_type *sem_type = semantic_type_get (s->type_name, NULL);
if (sem_type)
sem_type->status = declared;
}
}
static void
semantic_type_check_defined (semantic_type *sem_type)
{
/* <*> and <> do not have to be "declared". */
if (sem_type->status == declared
|| !*sem_type->tag
|| STREQ (sem_type->tag, "*"))
{
for (int i = 0; i < 2; ++i)
if (sem_type->props[i].kind != CODE_PROPS_NONE
&& ! sem_type->props[i].is_used)
complain (&sem_type->location, Wother,
_("useless %s for type <%s>"),
code_props_type_string (i), sem_type->tag);
}
else
complain (&sem_type->location, Wother,
_("type <%s> is used, but is not associated to any symbol"),
sem_type->tag);
}
/*-------------------------------------------------------------------.
| Merge the properties (precedence, associativity, etc.) of SYM, and |
| its string-named alias STR; check consistency. |
`-------------------------------------------------------------------*/
static void
symbol_merge_properties (symbol *sym, symbol *str)
{
if (str->content->type_name != sym->content->type_name)
{
if (str->content->type_name)
symbol_type_set (sym,
str->content->type_name, str->content->type_loc);
else
symbol_type_set (str,
sym->content->type_name, sym->content->type_loc);
}
for (int i = 0; i < CODE_PROPS_SIZE; ++i)
if (str->content->props[i].code)
symbol_code_props_set (sym, i, &str->content->props[i]);
else if (sym->content->props[i].code)
symbol_code_props_set (str, i, &sym->content->props[i]);
if (sym->content->prec || str->content->prec)
{
if (str->content->prec)
symbol_precedence_set (sym, str->content->prec, str->content->assoc,
str->content->prec_loc);
else
symbol_precedence_set (str, sym->content->prec, sym->content->assoc,
sym->content->prec_loc);
}
}
void
symbol_make_alias (symbol *sym, symbol *str, location loc)
{
if (sym->content->class != token_sym)
complain (&loc, complaint,
_("nonterminals cannot be given a string alias"));
else if (str->alias)
complain (&loc, Wother,
_("symbol %s used more than once as a literal string"), str->tag);
else if (sym->alias)
complain (&loc, Wother,
_("symbol %s given more than one literal string"), sym->tag);
else
{
symbol_merge_properties (sym, str);
sym_content_free (str->content);
str->content = sym->content;
str->content->symbol = str;
str->is_alias = true;
str->alias = sym;
sym->alias = str;
}
}
/*-------------------------------------------------------------------.
| Assign a symbol number, and write the definition of the token name |
| into FDEFINES. Put in SYMBOLS. |
`-------------------------------------------------------------------*/
static void
symbol_pack (symbol *sym)
{
aver (sym->content->number != NUMBER_UNDEFINED);
if (sym->content->class == nterm_sym)
sym->content->number += ntokens;
symbols[sym->content->number] = sym->content->symbol;
}
static void
complain_code_redeclared (int num, const symbol *first, const symbol *second)
{
symbols_sort (&first, &second);
complain (&second->location, complaint,
_("code %d reassigned to token %s"),
num, second->tag);
subcomplain (&first->location, complaint,
_("previous declaration for %s"),
first->tag);
}
/*-------------------------------------------------.
| Put SYM in TOKEN_TRANSLATIONS if it is a token. |
`-------------------------------------------------*/
static void
symbol_translation (const symbol *sym)
{
if (sym->content->class == token_sym && !sym->is_alias)
{
/* A token whose translation has already been set? */
if (token_translations[sym->content->code]
!= undeftoken->content->number)
complain_code_redeclared
(sym->content->code,
symbols[token_translations[sym->content->code]], sym);
else
token_translations[sym->content->code]
= sym->content->number;
}
}
/*---------------------------------------.
| Symbol and semantic type hash tables. |
`---------------------------------------*/
/* Initial capacity of symbol and semantic type hash table. */
#define HT_INITIAL_CAPACITY 257
static inline bool
hash_compare_symbol (const symbol *m1, const symbol *m2)
{
/* Since tags are unique, we can compare the pointers themselves. */
return UNIQSTR_EQ (m1->tag, m2->tag);
}
static inline bool
hash_compare_semantic_type (const semantic_type *m1, const semantic_type *m2)
{
/* Since names are unique, we can compare the pointers themselves. */
return UNIQSTR_EQ (m1->tag, m2->tag);
}
static bool
hash_symbol_comparator (void const *m1, void const *m2)
{
return hash_compare_symbol (m1, m2);
}
static bool
hash_semantic_type_comparator (void const *m1, void const *m2)
{
return hash_compare_semantic_type (m1, m2);
}
static inline size_t
hash_symbol (const symbol *m, size_t tablesize)
{
/* Since tags are unique, we can hash the pointer itself. */
return ((uintptr_t) m->tag) % tablesize;
}
static inline size_t
hash_semantic_type (const semantic_type *m, size_t tablesize)
{
/* Since names are unique, we can hash the pointer itself. */
return ((uintptr_t) m->tag) % tablesize;
}
static size_t
hash_symbol_hasher (void const *m, size_t tablesize)
{
return hash_symbol (m, tablesize);
}
static size_t
hash_semantic_type_hasher (void const *m, size_t tablesize)
{
return hash_semantic_type (m, tablesize);
}
/*-------------------------------.
| Create the symbol hash table. |
`-------------------------------*/
void
symbols_new (void)
{
symbol_table = hash_xinitialize (HT_INITIAL_CAPACITY,
NULL,
hash_symbol_hasher,
hash_symbol_comparator,
symbol_free);
/* Construct the acceptsymbol symbol. */
acceptsymbol = symbol_get ("$accept", empty_loc);
acceptsymbol->content->class = nterm_sym;
acceptsymbol->content->number = nnterms++;
/* Construct the YYerror/"error" token */
errtoken = symbol_get ("YYerror", empty_loc);
errtoken->content->class = token_sym;
errtoken->content->number = ntokens++;
{
symbol *alias = symbol_get ("error", empty_loc);
symbol_class_set (alias, token_sym, empty_loc, false);
symbol_make_alias (errtoken, alias, empty_loc);
}
/* Construct the YYUNDEF/"$undefined" token that represents all
undefined literal tokens. It is always symbol number 2. */
undeftoken = symbol_get ("YYUNDEF", empty_loc);
undeftoken->content->class = token_sym;
undeftoken->content->number = ntokens++;
{
symbol *alias = symbol_get ("$undefined", empty_loc);
symbol_class_set (alias, token_sym, empty_loc, false);
symbol_make_alias (undeftoken, alias, empty_loc);
}
semantic_type_table = hash_xinitialize (HT_INITIAL_CAPACITY,
NULL,
hash_semantic_type_hasher,
hash_semantic_type_comparator,
free);
}
/*----------------------------------------------------------------.
| Find the symbol named KEY, and return it. If it does not exist |
| yet, create it. |
`----------------------------------------------------------------*/
symbol *
symbol_from_uniqstr (const uniqstr key, location loc)
{
symbol probe;
probe.tag = key;
symbol *res = hash_lookup (symbol_table, &probe);
if (!res)
{
/* First insertion in the hash. */
aver (!symbols_sorted);
res = symbol_new (key, loc);
hash_xinsert (symbol_table, res);
}
return res;
}
/*-----------------------------------------------------------------------.
| Find the semantic type named KEY, and return it. If it does not exist |
| yet, create it. |
`-----------------------------------------------------------------------*/
semantic_type *
semantic_type_from_uniqstr (const uniqstr key, const location *loc)
{
semantic_type probe;
probe.tag = key;
semantic_type *res = hash_lookup (semantic_type_table, &probe);
if (!res)
{
/* First insertion in the hash. */
res = semantic_type_new (key, loc);
hash_xinsert (semantic_type_table, res);
}
return res;
}
/*----------------------------------------------------------------.
| Find the symbol named KEY, and return it. If it does not exist |
| yet, create it. |
`----------------------------------------------------------------*/
symbol *
symbol_get (const char *key, location loc)
{
return symbol_from_uniqstr (uniqstr_new (key), loc);
}
/*-----------------------------------------------------------------------.
| Find the semantic type named KEY, and return it. If it does not exist |
| yet, create it. |
`-----------------------------------------------------------------------*/
semantic_type *
semantic_type_get (const char *key, const location *loc)
{
return semantic_type_from_uniqstr (uniqstr_new (key), loc);
}
/*------------------------------------------------------------------.
| Generate a dummy nonterminal, whose name cannot conflict with the |
| user's names. |
`------------------------------------------------------------------*/
symbol *
dummy_symbol_get (location loc)
{
/* Incremented for each generated symbol. */
static int dummy_count = 0;
char buf[32];
int len = snprintf (buf, sizeof buf, "$@%d", ++dummy_count);
assure (len < sizeof buf);
symbol *sym = symbol_get (buf, loc);
sym->content->class = nterm_sym;
return sym;
}
bool
symbol_is_dummy (symbol const *sym)
{
return sym->tag[0] == '@' || (sym->tag[0] == '$' && sym->tag[1] == '@');
}
/*-------------------.
| Free the symbols. |
`-------------------*/
void
symbols_free (void)
{
hash_free (symbol_table);
hash_free (semantic_type_table);
free (symbols);
free (symbols_sorted);
free (semantic_types_sorted);
}
static int
symbol_cmp (void const *a, void const *b)
{
return location_cmp ((*(symbol * const *)a)->location,
(*(symbol * const *)b)->location);
}