mirror of
https://git.savannah.gnu.org/git/bison.git
synced 2026-03-09 12:23:04 +00:00
235892350f
On
%%
exp: {;} {$$;} { $$ = $1; }
instead of reporting (with -fcaret -Wmidrule-value)
midrule.y:2.6-8: warning: unset value: $$ [-Wmidrule-values]
exp: {;} {$$;} { $$ = $1; }
^^^
midrule.y:2.6-27: warning: unused value: $2 [-Wmidrule-values]
exp: {;} {$$;} { $$ = $1; }
^^^^^^^^^^^^^^^^^^^^^^
report
midrule.y:2.6-8: warning: unset value: $$
exp: {;} {$$;} { $$ = $1; }
^^^
midrule.y:2.10-14: warning: unused value: $2
exp: {;} {$$;} { $$ = $1; }
^^^^^
* src/reader.c (grammar_rule_check): When warning about the value of a
midrule action, use the location of the midrule action instead of the
location of the rule.
the location of the part of the rule.
* tests/actions.at (Default %printer and %destructor for mid-rule values):
Adjust expectations
* tests/input.at (Unused values with default %destructor): Ditto.
(AT_CHECK_UNUSED_VALUES): Ditto.
And use -fcaret.
750 lines
24 KiB
C
750 lines
24 KiB
C
/* Input parser for Bison
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Copyright (C) 1984, 1986, 1989, 1992, 1998, 2000-2003, 2005-2007,
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2009-2012 Free Software Foundation, Inc.
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This file is part of Bison, the GNU Compiler Compiler.
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This program 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 3 of the License, or
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(at your option) any later version.
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This program 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 this program. If not, see <http://www.gnu.org/licenses/>. */
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#include <config.h>
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#include "system.h"
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#include <quote.h>
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#include "complain.h"
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#include "conflicts.h"
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#include "files.h"
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#include "getargs.h"
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#include "gram.h"
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#include "muscle-tab.h"
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#include "reader.h"
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#include "symlist.h"
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#include "symtab.h"
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#include "scan-gram.h"
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#include "scan-code.h"
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static void prepare_percent_define_front_end_variables (void);
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static void check_and_convert_grammar (void);
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static symbol_list *grammar = NULL;
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static bool start_flag = false;
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merger_list *merge_functions;
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/* Was %union seen? */
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bool union_seen = false;
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/* Was a tag seen? */
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bool tag_seen = false;
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/* Should rules have a default precedence? */
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bool default_prec = true;
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/*-----------------------.
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| Set the start symbol. |
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`-----------------------*/
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void
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grammar_start_symbol_set (symbol *sym, location loc)
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{
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if (start_flag)
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complain_at (loc, _("multiple %s declarations"), "%start");
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else
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{
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start_flag = true;
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startsymbol = sym;
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startsymbol_location = loc;
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}
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}
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/*------------------------------------------------------------------------.
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| Return the merger index for a merging function named NAME. Records the |
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| function, if new, in MERGER_LIST. |
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`------------------------------------------------------------------------*/
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static int
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get_merge_function (uniqstr name)
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{
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merger_list *syms;
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merger_list head;
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int n;
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if (! glr_parser)
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return 0;
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head.next = merge_functions;
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for (syms = &head, n = 1; syms->next; syms = syms->next, n += 1)
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if (UNIQSTR_EQ (name, syms->next->name))
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break;
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if (syms->next == NULL)
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{
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syms->next = xmalloc (sizeof syms->next[0]);
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syms->next->name = uniqstr_new (name);
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/* After all symbol type declarations have been parsed, packgram invokes
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record_merge_function_type to set the type. */
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syms->next->type = NULL;
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syms->next->next = NULL;
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merge_functions = head.next;
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}
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return n;
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}
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/*-------------------------------------------------------------------------.
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| For the existing merging function with index MERGER, record the result |
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| type as TYPE as required by the lhs of the rule whose %merge declaration |
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| is at DECLARATION_LOC. |
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`-------------------------------------------------------------------------*/
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static void
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record_merge_function_type (int merger, uniqstr type, location declaration_loc)
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{
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int merger_find;
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merger_list *merge_function;
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if (merger <= 0)
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return;
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if (type == NULL)
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type = uniqstr_new ("");
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merger_find = 1;
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for (merge_function = merge_functions;
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merge_function != NULL && merger_find != merger;
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merge_function = merge_function->next)
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merger_find += 1;
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aver (merge_function != NULL && merger_find == merger);
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if (merge_function->type != NULL && !UNIQSTR_EQ (merge_function->type, type))
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{
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unsigned indent = 0;
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complain_at_indent (declaration_loc, &indent,
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_("result type clash on merge function %s: "
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"<%s> != <%s>"),
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quote (merge_function->name), type,
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merge_function->type);
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indent += SUB_INDENT;
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complain_at_indent (merge_function->type_declaration_location, &indent,
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_("previous declaration"));
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}
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merge_function->type = uniqstr_new (type);
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merge_function->type_declaration_location = declaration_loc;
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}
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/*--------------------------------------.
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| Free all merge-function definitions. |
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`--------------------------------------*/
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void
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free_merger_functions (void)
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{
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merger_list *L0 = merge_functions;
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while (L0)
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{
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merger_list *L1 = L0->next;
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free (L0);
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L0 = L1;
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}
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}
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/*-------------------------------------------------------------------.
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| Parse the input grammar into a one symbol_list structure. Each |
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| rule is represented by a sequence of symbols: the left hand side |
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| followed by the contents of the right hand side, followed by a |
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| null pointer instead of a symbol to terminate the rule. The next |
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| symbol is the lhs of the following rule. |
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| |
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| All actions are copied out, labelled by the rule number they apply |
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| to. |
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`-------------------------------------------------------------------*/
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/* The (currently) last symbol of GRAMMAR. */
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static symbol_list *grammar_end = NULL;
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/* Append SYM to the grammar. */
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static symbol_list *
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grammar_symbol_append (symbol *sym, location loc)
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{
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symbol_list *p = symbol_list_sym_new (sym, loc);
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if (grammar_end)
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grammar_end->next = p;
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else
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grammar = p;
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grammar_end = p;
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/* A null SYM stands for an end of rule; it is not an actual
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part of it. */
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if (sym)
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++nritems;
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return p;
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}
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static void
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assign_named_ref (symbol_list *p, named_ref *name)
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{
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symbol *sym = p->content.sym;
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if (name->id == sym->tag)
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{
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warn_at (name->loc,
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_("duplicated symbol name for %s ignored"),
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quote (sym->tag));
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named_ref_free (name);
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}
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else
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p->named_ref = name;
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}
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/* The rule currently being defined, and the previous rule.
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CURRENT_RULE points to the first LHS of the current rule, while
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PREVIOUS_RULE_END points to the *end* of the previous rule (NULL). */
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static symbol_list *current_rule = NULL;
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static symbol_list *previous_rule_end = NULL;
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/*----------------------------------------------.
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| Create a new rule for LHS in to the GRAMMAR. |
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`----------------------------------------------*/
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void
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grammar_current_rule_begin (symbol *lhs, location loc,
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named_ref *lhs_name)
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{
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symbol_list* p;
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/* Start a new rule and record its lhs. */
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++nrules;
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previous_rule_end = grammar_end;
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p = grammar_symbol_append (lhs, loc);
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if (lhs_name)
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assign_named_ref (p, named_ref_copy (lhs_name));
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current_rule = grammar_end;
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/* Mark the rule's lhs as a nonterminal if not already so. */
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if (lhs->class == unknown_sym)
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{
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lhs->class = nterm_sym;
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lhs->number = nvars;
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++nvars;
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}
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else if (lhs->class == token_sym)
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complain_at (loc, _("rule given for %s, which is a token"), lhs->tag);
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}
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/*----------------------------------------------------------------------.
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| A symbol should be used if either: |
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| 1. It has a destructor. |
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| 2. The symbol is a mid-rule symbol (i.e., the generated LHS |
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| replacing a mid-rule action) that was assigned to or used, as in |
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| "exp: { $$ = 1; } { $$ = $1; }". |
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`----------------------------------------------------------------------*/
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static bool
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symbol_should_be_used (symbol_list const *s, bool *midrule_warning)
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{
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if (symbol_destructor_get (s->content.sym)->code)
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return true;
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if ((s->midrule && s->midrule->action_props.is_value_used)
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|| (s->midrule_parent_rule
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&& symbol_list_n_get (s->midrule_parent_rule,
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s->midrule_parent_rhs_index)
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->action_props.is_value_used))
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{
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*midrule_warning = true;
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return true;
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}
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return false;
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}
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/*----------------------------------------------------------------.
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| Check that the rule R is properly defined. For instance, there |
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| should be no type clash on the default action. |
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`----------------------------------------------------------------*/
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static void
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grammar_rule_check (const symbol_list *r)
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{
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/* Type check.
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If there is an action, then there is nothing we can do: the user
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is allowed to shoot herself in the foot.
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Don't worry about the default action if $$ is untyped, since $$'s
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value can't be used. */
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if (!r->action_props.code && r->content.sym->type_name)
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{
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symbol *first_rhs = r->next->content.sym;
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/* If $$ is being set in default way, report if any type mismatch. */
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if (first_rhs)
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{
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char const *lhs_type = r->content.sym->type_name;
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const char *rhs_type =
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first_rhs->type_name ? first_rhs->type_name : "";
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if (!UNIQSTR_EQ (lhs_type, rhs_type))
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warn_at (r->location,
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_("type clash on default action: <%s> != <%s>"),
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lhs_type, rhs_type);
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}
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/* Warn if there is no default for $$ but we need one. */
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else
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warn_at (r->location,
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_("empty rule for typed nonterminal, and no action"));
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}
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/* Check that symbol values that should be used are in fact used. */
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{
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symbol_list const *l = r;
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int n = 0;
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for (; l && l->content.sym; l = l->next, ++n)
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{
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bool midrule_warning = false;
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if (!l->action_props.is_value_used
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&& symbol_should_be_used (l, &midrule_warning)
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/* The default action, $$ = $1, `uses' both. */
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&& (r->action_props.code || (n != 0 && n != 1)))
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{
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void (*warn_at_ptr)(location, char const*, ...) =
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midrule_warning ? midrule_value_at : warn_at;
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if (n)
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warn_at_ptr (l->location, _("unused value: $%d"), n);
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else
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warn_at_ptr (l->location, _("unset value: $$"));
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}
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}
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}
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/* See comments in grammar_current_rule_prec_set for how POSIX
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mandates this complaint. It's only for identifiers, so skip
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it for char literals and strings, which are always tokens. */
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if (r->ruleprec
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&& r->ruleprec->tag[0] != '\'' && r->ruleprec->tag[0] != '"'
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&& !r->ruleprec->declared && !r->ruleprec->prec)
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warn_at (r->location, _("token for %%prec is not defined: %s"),
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r->ruleprec->tag);
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}
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/*-------------------------------------.
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| End the currently being grown rule. |
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`-------------------------------------*/
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void
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grammar_current_rule_end (location loc)
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{
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/* Put an empty link in the list to mark the end of this rule */
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grammar_symbol_append (NULL, grammar_end->location);
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current_rule->location = loc;
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}
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/*-------------------------------------------------------------------.
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| The previous action turns out the be a mid-rule action. Attach it |
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| to the current rule, i.e., create a dummy symbol, attach it this |
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| mid-rule action, and append this dummy nonterminal to the current |
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| rule. |
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`-------------------------------------------------------------------*/
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void
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grammar_midrule_action (void)
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{
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/* Since the action was written out with this rule's number, we must
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give the new rule this number by inserting the new rule before
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it. */
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/* Make a DUMMY nonterminal, whose location is that of the midrule
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action. Create the MIDRULE. */
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location dummy_location = current_rule->action_props.location;
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symbol *dummy = dummy_symbol_get (dummy_location);
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symbol_list *midrule = symbol_list_sym_new (dummy, dummy_location);
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/* Remember named_ref of previous action. */
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named_ref *action_name = current_rule->action_props.named_ref;
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/* Make a new rule, whose body is empty, before the current one, so
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that the action just read can belong to it. */
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++nrules;
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++nritems;
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/* Attach its location and actions to that of the DUMMY. */
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midrule->location = dummy_location;
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code_props_rule_action_init (&midrule->action_props,
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current_rule->action_props.code,
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current_rule->action_props.location,
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midrule, 0);
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code_props_none_init (¤t_rule->action_props);
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if (previous_rule_end)
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previous_rule_end->next = midrule;
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else
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grammar = midrule;
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/* End the dummy's rule. */
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midrule->next = symbol_list_sym_new (NULL, dummy_location);
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midrule->next->next = current_rule;
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previous_rule_end = midrule->next;
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/* Insert the dummy nonterminal replacing the midrule action into
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the current rule. Bind it to its dedicated rule. */
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grammar_current_rule_symbol_append (dummy, dummy_location,
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action_name);
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grammar_end->midrule = midrule;
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midrule->midrule_parent_rule = current_rule;
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midrule->midrule_parent_rhs_index = symbol_list_length (current_rule->next);
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}
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/* Set the precedence symbol of the current rule to PRECSYM. */
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void
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grammar_current_rule_prec_set (symbol *precsym, location loc)
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{
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/* POSIX says that any identifier is a nonterminal if it does not
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appear on the LHS of a grammar rule and is not defined by %token
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or by one of the directives that assigns precedence to a token. We
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ignore this here because the only kind of identifier that POSIX
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allows to follow a %prec is a token and because assuming it's a
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token now can produce more logical error messages. Nevertheless,
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grammar_rule_check does obey what we believe is the real intent of
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POSIX here: that an error be reported for any identifier that
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appears after %prec but that is not defined separately as a
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token. */
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symbol_class_set (precsym, token_sym, loc, false);
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if (current_rule->ruleprec)
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complain_at (loc, _("only one %s allowed per rule"), "%prec");
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current_rule->ruleprec = precsym;
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}
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/* Attach dynamic precedence DPREC to the current rule. */
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void
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grammar_current_rule_dprec_set (int dprec, location loc)
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{
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if (! glr_parser)
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warn_at (loc, _("%s affects only GLR parsers"), "%dprec");
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if (dprec <= 0)
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complain_at (loc, _("%s must be followed by positive number"), "%dprec");
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else if (current_rule->dprec != 0)
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complain_at (loc, _("only one %s allowed per rule"), "%dprec");
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current_rule->dprec = dprec;
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}
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/* Attach a merge function NAME with argument type TYPE to current
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rule. */
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void
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grammar_current_rule_merge_set (uniqstr name, location loc)
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{
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if (! glr_parser)
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warn_at (loc, _("%s affects only GLR parsers"), "%merge");
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if (current_rule->merger != 0)
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complain_at (loc, _("only one %s allowed per rule"), "%merge");
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current_rule->merger = get_merge_function (name);
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current_rule->merger_declaration_location = loc;
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}
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/* Attach SYM to the current rule. If needed, move the previous
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action as a mid-rule action. */
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void
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grammar_current_rule_symbol_append (symbol *sym, location loc,
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named_ref *name)
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{
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symbol_list *p;
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if (current_rule->action_props.code)
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grammar_midrule_action ();
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p = grammar_symbol_append (sym, loc);
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if (name)
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assign_named_ref(p, name);
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}
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/* Attach an ACTION to the current rule. */
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void
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grammar_current_rule_action_append (const char *action, location loc,
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named_ref *name)
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{
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if (current_rule->action_props.code)
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grammar_midrule_action ();
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/* After all symbol declarations have been parsed, packgram invokes
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code_props_translate_code. */
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code_props_rule_action_init (¤t_rule->action_props, action, loc,
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current_rule, name);
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}
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/*---------------------------------------------------------------.
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| Convert the rules into the representation using RRHS, RLHS and |
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| RITEM. |
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`---------------------------------------------------------------*/
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static void
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packgram (void)
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{
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unsigned int itemno = 0;
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rule_number ruleno = 0;
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symbol_list *p = grammar;
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||
ritem = xnmalloc (nritems + 1, sizeof *ritem);
|
||
|
||
/* This sentinel is used by build_relations in gram.c. */
|
||
*ritem++ = 0;
|
||
|
||
rules = xnmalloc (nrules, sizeof *rules);
|
||
|
||
while (p)
|
||
{
|
||
int rule_length = 0;
|
||
symbol *ruleprec = p->ruleprec;
|
||
record_merge_function_type (p->merger, p->content.sym->type_name,
|
||
p->merger_declaration_location);
|
||
rules[ruleno].user_number = ruleno;
|
||
rules[ruleno].number = ruleno;
|
||
rules[ruleno].lhs = p->content.sym;
|
||
rules[ruleno].rhs = ritem + itemno;
|
||
rules[ruleno].prec = NULL;
|
||
rules[ruleno].dprec = p->dprec;
|
||
rules[ruleno].merger = p->merger;
|
||
rules[ruleno].precsym = NULL;
|
||
rules[ruleno].location = p->location;
|
||
rules[ruleno].useful = true;
|
||
rules[ruleno].action = p->action_props.code;
|
||
rules[ruleno].action_location = p->action_props.location;
|
||
|
||
/* If the midrule's $$ is set or its $n is used, remove the `$' from the
|
||
symbol name so that it's a user-defined symbol so that the default
|
||
%destructor and %printer apply. */
|
||
if (p->midrule_parent_rule
|
||
&& (p->action_props.is_value_used
|
||
|| symbol_list_n_get (p->midrule_parent_rule,
|
||
p->midrule_parent_rhs_index)
|
||
->action_props.is_value_used))
|
||
p->content.sym->tag += 1;
|
||
|
||
/* Don't check the generated rule 0. It has no action, so some rhs
|
||
symbols may appear unused, but the parsing algorithm ensures that
|
||
%destructor's are invoked appropriately. */
|
||
if (p != grammar)
|
||
grammar_rule_check (p);
|
||
|
||
for (p = p->next; p && p->content.sym; p = p->next)
|
||
{
|
||
++rule_length;
|
||
|
||
/* Don't allow rule_length == INT_MAX, since that might
|
||
cause confusion with strtol if INT_MAX == LONG_MAX. */
|
||
if (rule_length == INT_MAX)
|
||
fatal_at (rules[ruleno].location, _("rule is too long"));
|
||
|
||
/* item_number = symbol_number.
|
||
But the former needs to contain more: negative rule numbers. */
|
||
ritem[itemno++] =
|
||
symbol_number_as_item_number (p->content.sym->number);
|
||
/* A rule gets by default the precedence and associativity
|
||
of its last token. */
|
||
if (p->content.sym->class == token_sym && default_prec)
|
||
rules[ruleno].prec = p->content.sym;
|
||
}
|
||
|
||
/* If this rule has a %prec,
|
||
the specified symbol's precedence replaces the default. */
|
||
if (ruleprec)
|
||
{
|
||
rules[ruleno].precsym = ruleprec;
|
||
rules[ruleno].prec = ruleprec;
|
||
}
|
||
/* An item ends by the rule number (negated). */
|
||
ritem[itemno++] = rule_number_as_item_number (ruleno);
|
||
aver (itemno < ITEM_NUMBER_MAX);
|
||
++ruleno;
|
||
aver (ruleno < RULE_NUMBER_MAX);
|
||
|
||
if (p)
|
||
p = p->next;
|
||
}
|
||
|
||
aver (itemno == nritems);
|
||
|
||
if (trace_flag & trace_sets)
|
||
ritem_print (stderr);
|
||
}
|
||
|
||
/*------------------------------------------------------------------.
|
||
| Read in the grammar specification and record it in the format |
|
||
| described in gram.h. All actions are copied into ACTION_OBSTACK, |
|
||
| in each case forming the body of a C function (YYACTION) which |
|
||
| contains a switch statement to decide which action to execute. |
|
||
`------------------------------------------------------------------*/
|
||
|
||
void
|
||
reader (void)
|
||
{
|
||
/* Initialize the symbol table. */
|
||
symbols_new ();
|
||
|
||
/* Construct the accept symbol. */
|
||
accept = symbol_get ("$accept", empty_location);
|
||
accept->class = nterm_sym;
|
||
accept->number = nvars++;
|
||
|
||
/* Construct the error token */
|
||
errtoken = symbol_get ("error", empty_location);
|
||
errtoken->class = token_sym;
|
||
errtoken->number = ntokens++;
|
||
|
||
/* Construct a token that represents all undefined literal tokens.
|
||
It is always token number 2. */
|
||
undeftoken = symbol_get ("$undefined", empty_location);
|
||
undeftoken->class = token_sym;
|
||
undeftoken->number = ntokens++;
|
||
|
||
gram_in = xfopen (grammar_file, "r");
|
||
|
||
gram__flex_debug = trace_flag & trace_scan;
|
||
gram_debug = trace_flag & trace_parse;
|
||
gram_scanner_initialize ();
|
||
gram_parse ();
|
||
prepare_percent_define_front_end_variables ();
|
||
|
||
if (! complaint_issued)
|
||
check_and_convert_grammar ();
|
||
|
||
xfclose (gram_in);
|
||
}
|
||
|
||
static void
|
||
prepare_percent_define_front_end_variables (void)
|
||
{
|
||
/* Set %define front-end variable defaults. */
|
||
muscle_percent_define_default ("lr.keep-unreachable-states", "false");
|
||
{
|
||
char *lr_type;
|
||
/* IELR would be a better default, but LALR is historically the
|
||
default. */
|
||
muscle_percent_define_default ("lr.type", "lalr");
|
||
lr_type = muscle_percent_define_get ("lr.type");
|
||
if (0 != strcmp (lr_type, "canonical-lr"))
|
||
muscle_percent_define_default ("lr.default-reductions", "most");
|
||
else
|
||
muscle_percent_define_default ("lr.default-reductions", "accepting");
|
||
free (lr_type);
|
||
}
|
||
|
||
/* Check %define front-end variables. */
|
||
{
|
||
static char const * const values[] = {
|
||
"lr.type", "lalr", "ielr", "canonical-lr", NULL,
|
||
"lr.default-reductions", "most", "consistent", "accepting", NULL,
|
||
NULL
|
||
};
|
||
muscle_percent_define_check_values (values);
|
||
}
|
||
}
|
||
|
||
|
||
/*-------------------------------------------------------------.
|
||
| Check the grammar that has just been read, and convert it to |
|
||
| internal form. |
|
||
`-------------------------------------------------------------*/
|
||
|
||
static void
|
||
check_and_convert_grammar (void)
|
||
{
|
||
/* Grammar has been read. Do some checking. */
|
||
if (nrules == 0)
|
||
fatal (_("no rules in the input grammar"));
|
||
|
||
/* If the user did not define her ENDTOKEN, do it now. */
|
||
if (!endtoken)
|
||
{
|
||
endtoken = symbol_get ("$end", empty_location);
|
||
endtoken->class = token_sym;
|
||
endtoken->number = 0;
|
||
/* Value specified by POSIX. */
|
||
endtoken->user_token_number = 0;
|
||
}
|
||
|
||
/* Report any undefined symbols and consider them nonterminals. */
|
||
symbols_check_defined ();
|
||
|
||
/* Find the start symbol if no %start. */
|
||
if (!start_flag)
|
||
{
|
||
symbol_list *node;
|
||
for (node = grammar;
|
||
node != NULL && symbol_is_dummy (node->content.sym);
|
||
node = node->next)
|
||
{
|
||
for (node = node->next;
|
||
node != NULL && node->content.sym != NULL;
|
||
node = node->next)
|
||
;
|
||
}
|
||
aver (node != NULL);
|
||
grammar_start_symbol_set (node->content.sym,
|
||
node->content.sym->location);
|
||
}
|
||
|
||
/* Insert the initial rule, whose line is that of the first rule
|
||
(not that of the start symbol):
|
||
|
||
accept: %start EOF. */
|
||
{
|
||
symbol_list *p = symbol_list_sym_new (accept, empty_location);
|
||
p->location = grammar->location;
|
||
p->next = symbol_list_sym_new (startsymbol, empty_location);
|
||
p->next->next = symbol_list_sym_new (endtoken, empty_location);
|
||
p->next->next->next = symbol_list_sym_new (NULL, empty_location);
|
||
p->next->next->next->next = grammar;
|
||
nrules += 1;
|
||
nritems += 3;
|
||
grammar = p;
|
||
}
|
||
|
||
aver (nsyms <= SYMBOL_NUMBER_MAXIMUM && nsyms == ntokens + nvars);
|
||
|
||
/* Assign the symbols their symbol numbers. Write #defines for the
|
||
token symbols into FDEFINES if requested. */
|
||
symbols_pack ();
|
||
|
||
/* Scan rule actions after invoking symbol_check_alias_consistency (in
|
||
symbols_pack above) so that token types are set correctly before the rule
|
||
action type checking.
|
||
|
||
Before invoking grammar_rule_check (in packgram below) on any rule, make
|
||
sure all actions have already been scanned in order to set `used' flags.
|
||
Otherwise, checking that a midrule's $$ should be set will not always work
|
||
properly because the check must forward-reference the midrule's parent
|
||
rule. For the same reason, all the `used' flags must be set before
|
||
checking whether to remove `$' from any midrule symbol name (also in
|
||
packgram). */
|
||
{
|
||
symbol_list *sym;
|
||
for (sym = grammar; sym; sym = sym->next)
|
||
code_props_translate_code (&sym->action_props);
|
||
}
|
||
|
||
/* Convert the grammar into the format described in gram.h. */
|
||
packgram ();
|
||
|
||
/* The grammar as a symbol_list is no longer needed. */
|
||
symbol_list_free (grammar);
|
||
}
|