+2006-10-21 Joel E. Denny <jdenny@ces.clemson.edu>
+
+ Don't apply the default %destructor/%printer to an unreferenced midrule
+ value. Mentioned at
+ <http://lists.gnu.org/archive/html/bison-patches/2006-09/msg00104.html>.
+ * src/symtab.c (dummy_symbol_get): Name all dummy symbols initially
+ like $@n instead of just @n so that the default %destructor/%printer
+ logic doesn't see them as user-defined symbols.
+ (symbol_is_dummy): Check for both forms of the name.
+ * src/reader.c (packgram): Remove the `$' from each midrule symbol
+ name for which the midrule value is referenced in any action.
+ * tests/actions.at (Default %printer and %destructor for mid-rule
+ values): New test.
+ * tests/regression.at (Rule Line Numbers, Web2c Report): Update output
+ for change to dummy symbol names.
+
2006-10-20 Joel E. Denny <jdenny@ces.clemson.edu>
Warn about unset midrule $$ if the corresponding $n is used.
rules = xnmalloc (nrules, sizeof *rules);
- /* Before invoking grammar_rule_check on any rule, make sure
- all actions have already been scanned in order to set `used' flags.
- Otherwise, checking that a midrule's $$ is set will not always work
- properly because the midrule check must forward-reference the midrule's
- parent rule. */
+ /* Before invoking grammar_rule_check on any rule, make sure all actions have
+ already been scanned in order to set `used' flags. Otherwise, checking
+ that a midrule's $$ should be set will not always work properly because
+ the check must forward-reference the midrule's parent rule. For the same
+ reason, all the `used' flags must be set before checking whether to remove
+ `$' from any midrule symbol name. */
while (p)
{
if (p->action)
rules[ruleno].action = p->action;
rules[ruleno].action_location = p->action_location;
+ /* If the midrule's $$ 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->used
+ || symbol_list_n_get (p->midrule_parent_rule,
+ p->midrule_parent_rhs_index)->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. */
symbol *sym;
- sprintf (buf, "@%d", ++dummy_count);
+ sprintf (buf, "$@%d", ++dummy_count);
sym = symbol_get (buf, loc);
sym->class = nterm_sym;
sym->number = nvars++;
bool
symbol_is_dummy (const symbol *sym)
{
- return sym->tag[0] == '@';
+ return sym->tag[0] == '@' || (sym->tag[0] == '$' && sym->tag[1] == '@');
}
/*-------------------.
AT_COMPILE([input])
AT_CLEANUP
+
+
+
+## ------------------------------------------------------ ##
+## Default %printer and %destructor for mid-rule values. ##
+## ------------------------------------------------------ ##
+
+AT_SETUP([Default %printer and %destructor for mid-rule values])
+
+AT_DATA_GRAMMAR([[input.y]],
+[[%debug /* So that %printer is actually compiled. */
+
+%{
+# include <stdio.h>
+# include <stdlib.h>
+ static void yyerror (const char *msg);
+ static int yylex (void);
+# define USE(SYM)
+# define YYLTYPE int
+# define YYLLOC_DEFAULT(Current, Rhs, N)
+# define YY_LOCATION_PRINT(File, Loc)
+%}
+
+%printer { fprintf (yyoutput, "%d", @$); } %symbol-default
+%destructor { fprintf (stderr, "DESTROY %d\n", @$); } %symbol-default
+
+%%
+
+start:
+ { @$ = 1; } // Not set or used.
+ { USE ($$); @$ = 2; } // Both set and used.
+ { USE ($$); @$ = 3; } // Only set.
+ { @$ = 4; } // Only used.
+ 'c'
+ { USE (($$, $2, $4, $5)); @$ = 0; }
+ ;
+
+%%
+
+static int
+yylex (void)
+{
+ static int called;
+ if (called++)
+ abort ();
+ return 0;
+}
+
+static void
+yyerror (const char *msg)
+{
+ fprintf (stderr, "%s\n", msg);
+}
+
+int
+main (void)
+{
+ yydebug = 1;
+ return yyparse ();
+}
+]])
+
+AT_CHECK([bison -o input.c input.y], 0,,
+[[input.y:31.3-23: warning: unset value: $$
+input.y:28.3-33.37: warning: unused value: $3
+]])
+
+AT_COMPILE([input])
+AT_PARSER_CHECK([./input], 1,,
+[[Starting parse
+Entering state 0
+Reducing stack by rule 1 (line 28):
+-> $$ = nterm $@1 (: )
+Stack now 0
+Entering state 2
+Reducing stack by rule 2 (line 29):
+-> $$ = nterm @2 (: 2)
+Stack now 0 2
+Entering state 4
+Reducing stack by rule 3 (line 30):
+-> $$ = nterm @3 (: 3)
+Stack now 0 2 4
+Entering state 5
+Reducing stack by rule 4 (line 31):
+-> $$ = nterm @4 (: 4)
+Stack now 0 2 4 5
+Entering state 6
+Reading a token: Now at end of input.
+syntax error
+Error: popping nterm @4 (: 4)
+DESTROY 4
+Stack now 0 2 4 5
+Error: popping nterm @3 (: 3)
+DESTROY 3
+Stack now 0 2 4
+Error: popping nterm @2 (: 2)
+DESTROY 2
+Stack now 0 2
+Error: popping nterm $@1 (: )
+Stack now 0
+Cleanup: discarding lookahead token $end (: )
+Stack now 0
+]])
+
+AT_CLEANUP
0 $accept: expr $end
- 1 @1: /* empty */
+ 1 $@1: /* empty */
- 2 expr: 'a' @1 'b'
+ 2 expr: 'a' $@1 'b'
- 3 @2: /* empty */
+ 3 $@2: /* empty */
- 4 expr: @2 'c'
+ 4 expr: $@2 'c'
Terminals, with rules where they appear
on left: 0
expr (7)
on left: 2 4, on right: 0
-@1 (8)
+$@1 (8)
on left: 1, on right: 2
-@2 (9)
+$@2 (9)
on left: 3, on right: 4
'a' shift, and go to state 1
- $default reduce using rule 3 (@2)
+ $default reduce using rule 3 ($@2)
expr go to state 2
- @2 go to state 3
+ $@2 go to state 3
state 1
- 2 expr: 'a' . @1 'b'
+ 2 expr: 'a' . $@1 'b'
- $default reduce using rule 1 (@1)
+ $default reduce using rule 1 ($@1)
- @1 go to state 4
+ $@1 go to state 4
state 2
state 3
- 4 expr: @2 . 'c'
+ 4 expr: $@2 . 'c'
'c' shift, and go to state 6
state 4
- 2 expr: 'a' @1 . 'b'
+ 2 expr: 'a' $@1 . 'b'
'b' shift, and go to state 7
state 6
- 4 expr: @2 'c' .
+ 4 expr: $@2 'c' .
$default reduce using rule 4 (expr)
state 7
- 2 expr: 'a' @1 'b' .
+ 2 expr: 'a' $@1 'b' .
$default reduce using rule 2 (expr)
]])
2 CONST_DEC_LIST: CONST_DEC
3 | CONST_DEC_LIST CONST_DEC
- 4 @1: /* empty */
+ 4 $@1: /* empty */
- 5 CONST_DEC: @1 undef_id_tok '=' const_id_tok ';'
+ 5 CONST_DEC: $@1 undef_id_tok '=' const_id_tok ';'
Terminals, with rules where they appear
on left: 2 3, on right: 1 3
CONST_DEC (10)
on left: 5, on right: 2 3
-@1 (11)
+$@1 (11)
on left: 4, on right: 5
0 $accept: . CONST_DEC_PART $end
- $default reduce using rule 4 (@1)
+ $default reduce using rule 4 ($@1)
CONST_DEC_PART go to state 1
CONST_DEC_LIST go to state 2
CONST_DEC go to state 3
- @1 go to state 4
+ $@1 go to state 4
state 1
1 CONST_DEC_PART: CONST_DEC_LIST .
3 CONST_DEC_LIST: CONST_DEC_LIST . CONST_DEC
- undef_id_tok reduce using rule 4 (@1)
+ undef_id_tok reduce using rule 4 ($@1)
$default reduce using rule 1 (CONST_DEC_PART)
CONST_DEC go to state 6
- @1 go to state 4
+ $@1 go to state 4
state 3
state 4
- 5 CONST_DEC: @1 . undef_id_tok '=' const_id_tok ';'
+ 5 CONST_DEC: $@1 . undef_id_tok '=' const_id_tok ';'
undef_id_tok shift, and go to state 7
state 7
- 5 CONST_DEC: @1 undef_id_tok . '=' const_id_tok ';'
+ 5 CONST_DEC: $@1 undef_id_tok . '=' const_id_tok ';'
'=' shift, and go to state 8
state 8
- 5 CONST_DEC: @1 undef_id_tok '=' . const_id_tok ';'
+ 5 CONST_DEC: $@1 undef_id_tok '=' . const_id_tok ';'
const_id_tok shift, and go to state 9
state 9
- 5 CONST_DEC: @1 undef_id_tok '=' const_id_tok . ';'
+ 5 CONST_DEC: $@1 undef_id_tok '=' const_id_tok . ';'
';' shift, and go to state 10
state 10
- 5 CONST_DEC: @1 undef_id_tok '=' const_id_tok ';' .
+ 5 CONST_DEC: $@1 undef_id_tok '=' const_id_tok ';' .
$default reduce using rule 5 (CONST_DEC)
]])
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