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Disable unset/unused mid-rule value warnings by default, and recognize

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--warnings=midrule-values to enable them.  Discussed starting at
<http://lists.gnu.org/archive/html/help-bison/2006-10/msg00030.html>.
* NEWS (2.3a+): Mention.
* src/getargs.c, src/getargs.h (warnings_args, warnings_types, enum
warnings): Add entry for midrule-values subargument.
* src/reader.c (symbol_should_be_used): Don't return true just because
the value is a set/used mid-rule value unless
--warnings=midrule-values was specified.
* tests/input.at (Unused values, Unused values before symbol
declarations): Run tests with and without --warnings=midrule-values.

* src/reader.c (check_and_convert_grammar): Use symbol_list_free rather
than LIST_FREE directly.
This commit is contained in:
Joel E. Denny
2006-11-01 06:09:40 +00:00
parent 89eb3c7653
commit 17bd8a736a
6 changed files with 81 additions and 32 deletions
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17
ChangeLog
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@@ -1,3 +1,20 @@
2006-10-31 Joel E. Denny <jdenny@ces.clemson.edu>
Disable unset/unused mid-rule value warnings by default, and recognize
--warnings=midrule-values to enable them. Discussed starting at
<http://lists.gnu.org/archive/html/help-bison/2006-10/msg00030.html>.
* NEWS (2.3a+): Mention.
* src/getargs.c, src/getargs.h (warnings_args, warnings_types, enum
warnings): Add entry for midrule-values subargument.
* src/reader.c (symbol_should_be_used): Don't return true just because
the value is a set/used mid-rule value unless
--warnings=midrule-values was specified.
* tests/input.at (Unused values, Unused values before symbol
declarations): Run tests with and without --warnings=midrule-values.
* src/reader.c (check_and_convert_grammar): Use symbol_list_free rather
than LIST_FREE directly.
2006-10-31 Joel E. Denny <jdenny@ces.clemson.edu> 2006-10-31 Joel E. Denny <jdenny@ces.clemson.edu>
Finish implementing --warnings=error, which should not be implied by Finish implementing --warnings=error, which should not be implied by

20
NEWS
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@@ -6,6 +6,26 @@ Changes in version 2.3a+ (????-??-??):
* The -g and --graph options now output graphs in Graphviz DOT format, * The -g and --graph options now output graphs in Graphviz DOT format,
not VCG format. not VCG format.
* Revised warning: unset or unused mid-rule values
Since Bison 2.2, Bison has warned about mid-rule values that are set but not
used within any of the actions of the parent rule. For example, Bison warns
about unused $2 in:
exp: '1' { $$ = 1; } '+' exp { $$ = $1 + $4; };
Now, Bison also warns about mid-rule values that are used but not set. For
example, Bison warns about unset $$ in the mid-rule action in:
exp: '1' { $1 = 1; } '+' exp { $$ = $2 + $4; };
However, Bison now disables both of these warnings by default since they
sometimes prove to be false alarms in existing grammars employing the Yacc
constructs $0 or $-N (where N is some positive integer).
To enable these warnings, specify the flag `--warnings=midrule-values' or
`-W', which is a synonym for `--warnings=all'.
* Bison now recognizes two separate kinds of default %destructor's and * Bison now recognizes two separate kinds of default %destructor's and
%printer's: %printer's:

10
src/getargs.c
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@@ -203,16 +203,18 @@ static const char * const warnings_args[] =
{ {
/* In a series of synonyms, present the most meaningful first, so /* In a series of synonyms, present the most meaningful first, so
that argmatch_valid be more readable. */ that argmatch_valid be more readable. */
"none - no warnings", "none - no warnings",
"yacc - incompatibilities with POSIX YACC", "midrule-values - unset or unused midrule values",
"all - all of the above", "yacc - incompatibilities with POSIX YACC",
"error - warnings are errors", "all - all of the above",
"error - warnings are errors",
0 0
}; };
static const int warnings_types[] = static const int warnings_types[] =
{ {
warnings_none, warnings_none,
warnings_midrule_values,
warnings_yacc, warnings_yacc,
warnings_all, warnings_all,
warnings_error warnings_error

3
src/getargs.h
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@@ -111,7 +111,8 @@ enum warnings
{ {
warnings_none = 0, /**< Issue no warnings. */ warnings_none = 0, /**< Issue no warnings. */
warnings_error = 1 << 0, /**< Warnings are treated as errors. */ warnings_error = 1 << 0, /**< Warnings are treated as errors. */
warnings_yacc = 1 << 1, /**< POSIXME. */ warnings_midrule_values = 1 << 1, /**< Unset or unused midrule values. */
warnings_yacc = 1 << 2, /**< POSIXME. */
warnings_all = ~warnings_error /**< All above warnings. */ warnings_all = ~warnings_error /**< All above warnings. */
}; };
/** What warnings are issued. */ /** What warnings are issued. */

23
src/reader.c
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@@ -243,19 +243,24 @@ grammar_current_rule_begin (symbol *lhs, location loc)
/*----------------------------------------------------------------------. /*----------------------------------------------------------------------.
| A symbol should be used if it has a destructor, or if it is a | | A symbol should be used if either: |
| mid-rule symbol (i.e., the generated LHS replacing a mid-rule | | 1. It has a destructor. |
| action) that was assigned to, as in "exp: { $$ = 1; } { $$ = $1; }". | | 2. --warnings=midrule-values and the symbol is a mid-rule symbol |
| (i.e., the generated LHS replacing a mid-rule action) that was |
| assigned to or used, as in "exp: { $$ = 1; } { $$ = $1; }". |
`----------------------------------------------------------------------*/ `----------------------------------------------------------------------*/
static bool static bool
symbol_should_be_used (symbol_list const *s) symbol_should_be_used (symbol_list const *s)
{ {
return (symbol_destructor_get (s->content.sym) if (symbol_destructor_get (s->content.sym))
|| (s->midrule && s->midrule->used) return true;
|| (s->midrule_parent_rule if (warnings_flag & warnings_midrule_values)
&& symbol_list_n_get (s->midrule_parent_rule, return ((s->midrule && s->midrule->used)
s->midrule_parent_rhs_index)->used)); || (s->midrule_parent_rule
&& symbol_list_n_get (s->midrule_parent_rule,
s->midrule_parent_rhs_index)->used));
return false;
} }
/*----------------------------------------------------------------. /*----------------------------------------------------------------.
@@ -666,5 +671,5 @@ check_and_convert_grammar (void)
packgram (); packgram ();
/* The grammar as a symbol_list is no longer needed. */ /* The grammar as a symbol_list is no longer needed. */
LIST_FREE (symbol_list, grammar); symbol_list_free (grammar);
} }

40
tests/input.at
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@@ -80,13 +80,15 @@ m4_define([_AT_UNUSED_VALUES_DECLARATIONS],
%destructor { destroy ($$); } INT a b c d e f g h i j k l;]]]) %destructor { destroy ($$); } INT a b c d e f g h i j k l;]]])
# AT_CHECK_UNUSED_VALUES(DECLARATIONS_AFTER) # AT_CHECK_UNUSED_VALUES(DECLARATIONS_AFTER, CHECK_MIDRULE_VALUES)
# -------------------------------------------- # ------------------------------------------------------------------
# Generate a grammar to test unused values, # Generate a grammar to test unused values,
# compile it, run it. If DECLARATIONS_AFTER # compile it, run it. If DECLARATIONS_AFTER
# is set, then the token, type, and destructor # is set, then the token, type, and destructor
# declarations are generated after the rules # declarations are generated after the rules
# rather than before. # rather than before. If CHECK_MIDRULE_VALUES
# is set, then --warnings=midrule-values is
# set.
m4_define([AT_CHECK_UNUSED_VALUES], m4_define([AT_CHECK_UNUSED_VALUES],
[AT_DATA([input.y], [AT_DATA([input.y],
@@ -116,19 +118,19 @@ l: INT | INT { $<integer>$ = $<integer>1; } INT { $<integer>$ = $<integer>2 + $<
_AT_UNUSED_VALUES_DECLARATIONS]) _AT_UNUSED_VALUES_DECLARATIONS])
) )
AT_CHECK([bison input.y], [0], [], AT_CHECK([bison]m4_ifval($2, [ --warnings=midrule-values ])[ input.y], [0], [],
[[input.y:11.10-32: warning: unset value: $]$[ [[input.y:11.10-32: warning: unset value: $]$[
input.y:11.10-32: warning: unused value: $]1[ input.y:11.10-32: warning: unused value: $]1[
input.y:11.10-32: warning: unused value: $]3[ input.y:11.10-32: warning: unused value: $]3[
input.y:11.10-32: warning: unused value: $]5[ input.y:11.10-32: warning: unused value: $]5[
input.y:12.9: warning: empty rule for typed nonterminal, and no action input.y:12.9: warning: empty rule for typed nonterminal, and no action
input.y:13.14-19: warning: unset value: $$ ]]m4_ifval($2, [[[input.y:13.14-19: warning: unset value: $$
input.y:13.25-39: warning: unset value: $$ input.y:13.25-39: warning: unset value: $$
input.y:13.10-59: warning: unset value: $]$[ ]]])[[input.y:13.10-59: warning: unset value: $]$[
input.y:13.10-59: warning: unused value: $]3[ input.y:13.10-59: warning: unused value: $]3[
input.y:13.10-59: warning: unused value: $]5[ input.y:13.10-59: warning: unused value: $]5[
input.y:14.14-16: warning: unset value: $$ ]]m4_ifval($2, [[[input.y:14.14-16: warning: unset value: $$
input.y:14.10-47: warning: unset value: $]$[ ]]])[[input.y:14.10-47: warning: unset value: $]$[
input.y:14.10-47: warning: unused value: $]3[ input.y:14.10-47: warning: unused value: $]3[
input.y:14.10-47: warning: unused value: $]5[ input.y:14.10-47: warning: unused value: $]5[
input.y:15.10-36: warning: unset value: $]$[ input.y:15.10-36: warning: unset value: $]$[
@@ -136,21 +138,21 @@ input.y:15.10-36: warning: unused value: $]3[
input.y:15.10-36: warning: unused value: $]5[ input.y:15.10-36: warning: unused value: $]5[
input.y:17.10-58: warning: unset value: $]$[ input.y:17.10-58: warning: unset value: $]$[
input.y:17.10-58: warning: unused value: $]1[ input.y:17.10-58: warning: unused value: $]1[
input.y:17.10-58: warning: unused value: $]2[ ]]m4_ifval($2, [[[input.y:17.10-58: warning: unused value: $]2[
input.y:17.10-58: warning: unused value: $]3[ ]]])[[input.y:17.10-58: warning: unused value: $]3[
input.y:17.10-58: warning: unused value: $]4[ ]]m4_ifval($2, [[[input.y:17.10-58: warning: unused value: $]4[
input.y:17.10-58: warning: unused value: $]5[ ]]])[[input.y:17.10-58: warning: unused value: $]5[
input.y:18.10-72: warning: unset value: $]$[ input.y:18.10-72: warning: unset value: $]$[
input.y:18.10-72: warning: unused value: $]1[ input.y:18.10-72: warning: unused value: $]1[
input.y:18.10-72: warning: unused value: $]3[ input.y:18.10-72: warning: unused value: $]3[
input.y:18.10-72: warning: unused value: $]4[ ]]m4_ifval($2, [[[input.y:18.10-72: warning: unused value: $]4[
input.y:18.10-72: warning: unused value: $]5[ ]]])[[input.y:18.10-72: warning: unused value: $]5[
input.y:20.10-55: warning: unused value: $]3[ ]]m4_ifval($2, [[[input.y:20.10-55: warning: unused value: $]3[
input.y:21.10-68: warning: unset value: $]$[ ]]])[[input.y:21.10-68: warning: unset value: $]$[
input.y:21.10-68: warning: unused value: $]1[ input.y:21.10-68: warning: unused value: $]1[
input.y:21.10-68: warning: unused value: $]2[ input.y:21.10-68: warning: unused value: $]2[
input.y:21.10-68: warning: unused value: $]4[ ]]m4_ifval($2, [[[input.y:21.10-68: warning: unused value: $]4[
]])]) ]]]))])
## --------------- ## ## --------------- ##
@@ -159,6 +161,7 @@ input.y:21.10-68: warning: unused value: $]4[
AT_SETUP([Unused values]) AT_SETUP([Unused values])
AT_CHECK_UNUSED_VALUES AT_CHECK_UNUSED_VALUES
AT_CHECK_UNUSED_VALUES(, [1])
AT_CLEANUP AT_CLEANUP
@@ -168,6 +171,7 @@ AT_CLEANUP
AT_SETUP([Unused values before symbol declarations]) AT_SETUP([Unused values before symbol declarations])
AT_CHECK_UNUSED_VALUES([1]) AT_CHECK_UNUSED_VALUES([1])
AT_CHECK_UNUSED_VALUES([1], [1])
AT_CLEANUP AT_CLEANUP