Currently on a grammar such as
exp : a '1' | a '2' | a '3' | b '1' | b '2' | b '3'
a:
b:
we count only one rr-conflict on the `b:` rule, i.e., we expect:
b: %expect-rr 1
although there are 3 conflicts in total. That's because in the
conflicted state we count only a single conflict, not three (one for
each of the lookaheads: '1', '2', '3').
State 0
0 $accept: . exp $end
1 exp: . a '1'
2 | . a '2'
3 | . a '3'
4 | . b '1'
5 | . b '2'
6 | . b '3'
7 a: . %empty ['1', '2', '3']
8 b: . %empty ['1', '2', '3']
'1' reduce using rule 7 (a)
'1' [reduce using rule 8 (b)]
'2' reduce using rule 7 (a)
'2' [reduce using rule 8 (b)]
'3' reduce using rule 7 (a)
'3' [reduce using rule 8 (b)]
$default reduce using rule 7 (a)
exp go to state 1
a go to state 2
b go to state 3
See https://lists.gnu.org/archive/html/bison-patches/2013-02/msg00106.html.
* src/conflicts.c (rule_has_state_rr_conflicts): Rename as...
(count_rule_state_sr_conflicts): this.
DWIM.
(count_rule_rr_conflicts): Adjust.
* tests/conflicts.at (%expect-rr in grammar rules)
(%expect-rr too much in grammar rules)
(%expect-rr not enough in grammar rules): New.
On a grammar such as
exp: "num" | "num" | "num"
we currently report only one RR conflict, instead of two.
This bug is present since the origins of Bison
commit 08089d5d35
Author: David MacKenzie <djm@djmnet.org>
Date: Tue Apr 20 05:42:52 1993 +0000
Initial revision
and was preserved in
commit 676385e29c
Author: Paul Hilfinger <Hilfinger@CS.Berkeley.EDU>
Date: Fri Jun 28 02:26:44 2002 +0000
Initial check-in introducing experimental GLR parsing. See entry in
ChangeLog dated 2002-06-27 from Paul Hilfinger for details.
See
https://lists.gnu.org/archive/html/bison-patches/2018-11/msg00011.html
* src/conflicts.h, src/conflicts.c (count_state_rr_conflicts)
(count_rr_conflicts): Use only the correct count of conflicts.
* tests/glr-regression.at: Fix expectations.
Currently on a grammar such as
exp: "number" | exp "+" exp | exp "*" exp
we count only one sr-conflict for both binary rules, i.e., we expect:
exp: "number" | exp "+" exp %expect 1 | exp "*" exp %expect 1
although there are 4 conflicts in total. That's because in the states
in conflict, for instance that for the "+" rule:
State 6
2 exp: exp . "+" exp
2 | exp "+" exp . [$end, "+", "*"]
3 | exp . "*" exp
"+" shift, and go to state 4
"*" shift, and go to state 5
"+" [reduce using rule 2 (exp)]
"*" [reduce using rule 2 (exp)]
$default reduce using rule 2 (exp)
we count only a single conflict, although there are two (one on "+"
and another with "*").
See https://lists.gnu.org/archive/html/bison-patches/2013-02/msg00106.html.
* src/conflicts.c (rule_has_state_sr_conflicts): Rename as...
(count_rule_state_sr_conflicts): this.
DWIM.
(count_rule_sr_conflicts): Adjust.
* tests/conflicts.at (%expect in grammar rules): New.
This change allows one to document (and check) which rules participate
in shift/reduce and reduce/reduce conflicts. This is particularly
important GLR parsers, where conflicts are a normal occurrence. For
example,
%glr-parser
%expect 1
%%
...
argument_list:
arguments %expect 1
| arguments ','
| %empty
;
arguments:
expression
| argument_list ',' expression
;
...
Looking at the output from -v, one can see that the shift-reduce
conflict here is due to the fact that the parser does not know whether
to reduce arguments to argument_list until it sees the token AFTER the
following ','. By marking the rule with %expect 1 (because there is a
conflict in one state), we document the source of the 1 overall shift-
reduce conflict.
In GLR parsers, we can use %expect-rr in a rule for reduce/reduce
conflicts. In this case, we mark each of the conflicting rules. For
example,
%glr-parser
%expect-rr 1
%%
stmt:
target_list '=' expr ';'
| expr_list ';'
;
target_list:
target
| target ',' target_list
;
target:
ID %expect-rr 1
;
expr_list:
expr
| expr ',' expr_list
;
expr:
ID %expect-rr 1
| ...
;
In a statement such as
x, y = 3, 4;
the parser must reduce x to a target or an expr, but does not know
which until it sees the '='. So we notate the two possible reductions
to indicate that each conflicts in one rule.
See https://lists.gnu.org/archive/html/bison-patches/2013-02/msg00105.html.
* doc/bison.texi (Suppressing Conflict Warnings): Document %expect,
%expect-rr in grammar rules.
* src/conflicts.c (count_state_rr_conflicts): Adjust comment.
(rule_has_state_sr_conflicts): New static function.
(count_rule_sr_conflicts): New static function.
(rule_nast_state_rr_conflicts): New static function.
(count_rule_rr_conflicts): New static function.
(rule_conflicts_print): New static function.
(conflicts_print): Also use rule_conflicts_print to report on individual
rules.
* src/gram.h (struct rule): Add new fields expected_sr_conflicts,
expected_rr_conflicts.
* src/reader.c (grammar_midrule_action): Transfer expected_sr_conflicts,
expected_rr_conflicts to new rule, and turn off in current_rule.
(grammar_current_rule_expect_sr): New function.
(grammar_current_rule_expect_rr): New function.
(packgram): Transfer expected_sr_conflicts, expected_rr_conflicts
to new rule.
* src/reader.h (grammar_current_rule_expect_sr): New function.
(grammar_current_rule_expect_rr): New function.
* src/symlist.c (symbol_list_sym_new): Initialize expected_sr_conflicts,
expected_rr_conflicts.
* src/symlist.h (struct symbol_list): Add new fields expected_sr_conflicts,
expected_rr_conflicts.
* tests/conflicts.at: Add tests "%expect in grammar rule not enough",
"%expect in grammar rule right.", "%expect in grammar rule too much."
* origin/maint:
build: don't try to generate docs when cross-compiling
package: fix a reporter's name
%union: fix the support for named %union
package: bump to 2015
flex: don't trust YY_USER_INIT
yacc.c: fix broken union when api.value.type=union and %defines are used
doc: fix missing xref
gnulib: update
location: remove some ugly debugging code traces
build: use abort to pacify compiler errors
package: bump to 2014
doc: specify documentation encoding
Rather than having duplicate info in the symbol and the alias that has
to be resolved later on, both the symbol and the alias have a common
pointer to a separate structure containing this info.
* src/symtab.h (sym_content): New structure.
* src/symtab.c (sym_content_new, sym_content_free, symbol_free): New
* src/AnnotationList.c, src/conflicts.c, src/gram.c, src/gram.h,
* src/graphviz.c, src/ielr.c, src/output.c, src/parse-gram.y, src/print.c
* src/print-xml.c, src/print_graph.c, src/reader.c, src/reduce.c,
* src/state.h, src/symlist.c, src/symtab.c, src/symtab.h, src/tables.c:
Adjust.
* tests/input.at: Fix expectations (order changes).
Record which symbol associativity is used, and display useless ones.
* src/symtab.h, src/symtab.c (register_assoc, print_assoc_warnings): New
* src/symtab.c (init_assoc, is_assoc_used): New
* src/main.c: Use print_assoc_warnings
* src/conflicts.c: Use register_assoc
* tests/conflicts.at (Useless associativity warning): New.
Due to the new warning, many tests had to be updated.
* tests/conflicts.at tests/existing.at tests/regression.at:
Add the associativity warning in the expected results.
* tests/java.at: Fix the java calculator's grammar to remove a useless
associativity.
* doc/bison.texi (mfcalc example): Fix associativity to remove
warning.
Symbols with precedence but no associativity, and whose precedence is
never used, can be declared with %token instead. The used precedence
relationships are recorded and a warning about useless ones is issued.
* src/conflicts.c (resolve_sr_conflict): Record precedence relation.
* src/symtab.c, src/symtab.h (prec_nodes, init_prec_nodes)
(symgraphlink_new, register_precedence_second_symbol)
(print_precedence_warnings): New.
Record relationships in a graph and warn about useless ones.
* src/main.c (main): Print precedence warnings.
* tests/conflicts.at: New.
The current routines used to display s/r and r/r conflicts are both
inconvenient from the programmer point of view (they do not use the
warning infrastructure) and for the user (the messages are rather
terse, not necessarily pleasant to read, and because they don't use
the same routines, they look different).
It was due to the belief (dating back to the initial checked-in
version of Bison) that, at some point, POSIX Yacc mandated the format
for these messages. Today, the Open Group's manual page for Yacc,
<http://pubs.opengroup.org/onlinepubs/009695399/utilities/yacc.html>,
explicitly states that the format of these messages is unspecified.
See commit be7280480c and
<http://lists.gnu.org/archive/html/bison-patches/2002-12/msg00027.html>.
For a discussion on the chosen warning format, see
http://lists.gnu.org/archive/html/bison-patches/2012-09/msg00039.html
In an effort to factor the handling of errors and warnings, use the
Bison warning routines to report these messages.
* src/conflicts.c (conflicts_print): Rewrite with clearer sections
about S/R and then R/R conflicts.
(conflict_report): Remove, inlined in its sole
caller...
(conflicts_output): here.
* tests/conflicts.at, tests/existing.at, tests/glr-regression.at,
* tests/reduce.at, tests/regression.at: Adjust the expected results.
* NEWS: Update.
* src/conflicts.c (conflicts_print): Complain about %expect-rr if not
in GLR mode, regardless of the number of reduce/reduce conflicts.
* tests/conflicts.at (%expect-rr non GLR): New test.
* NEWS: Update.
* src/complain.h : errors_flag variable
* src/complain.c : actual stuff happens here
* src/conflits.c : differentiated SR and RR conflicts
* src/getargs.c : flags_argmatch recognizes the new -Werror format
* src/system.h (obstack_finish0): New.
Use it to simplify several uses.
* src/muscle-tab.h (MUSCLE_INSERTF): New.
* src/muscle-tab.c: Use obstack_printf where simpler.
* maint:
use obstack_printf
scanner: restore a missing start condition
gnulib: update
maint: post-release administrivia
version 2.6.1
gnulib: update
maint: fix some syntax-check issues
tests: do not depend on __cplusplus to decide for C++ or C output
Conflicts:
NEWS
bootstrap.conf
cfg.mk
lib/.gitignore
This is not just nicer, it is also much safer, since we were
using sprintf...
* bootstrap.conf: Require it.
* src/system.h (obstack_fgrow1, obstack_fgrow2, obstack_fgrow3)
(obstack_fgrow4): Remove.
Adjust dependencies.
Forthcoming changes will use the warning categories much more often,
so shortening them will improve readability.
* src/complain.c, src/complain.h, src/conflicts.c,
* src/getargs.c, src/getargs.h, src/gram.c (enum warnings):
s/warnings_/W/g.
This change was made by applying emacs' untabify function to
nearly all files in Bison's repository. Required tabs in make
files, ChangeLog, regexps, and test code were manually skipped.
Other notable exceptions and changes are listed below.
* bootstrap: Skip because we sync this with gnulib.
* data/m4sugar/foreach.m4
* data/m4sugar/m4sugar.m4: Skip because we sync these with
Autoconf.
* djgpp: Skip because I don't know how to test djgpp properly, and
this code appears to be unmaintained anyway.
* README-hacking (Hacking): Specify that tabs should be avoided
where not required.
Thus, conflict reports are now affected by -Werror and -Wnone
(unless %expect or %expect-rr is specified). Reported by George
Neuner at
<http://lists.gnu.org/archive/html/bug-bison/2010-08/msg00002.html>.
* NEWS (2.5): Document.
* doc/bison.texinfo (Bison Options): Document.
* src/complain.c, src/complain.h (set_warning_issued): Export
function.
* src/conflicts.c (conflicts_print): Suppress conflict report
based on -Wno-conflicts-sr and -Wno-conflicts-rr, and treat
conflicts as errors if -Werror.
* src/getargs.c (warnings_flag): Initialize with
warnings_conflicts_sr and warnings_conflicts_rr as well.
(warnings_args, warnings_types): Add entries for
warnings_conflicts_sr and warnings_conflicts_rr.
(usage): Update.
* src/getargs.h (enum warnings): Add entries for
warnings_conflicts_sr and warnings_conflicts_rr.
* tests/conflicts.at (-W versus %expect and %expect-rr): New test
group.
* tests/local.at (AT_BISON_CHECK_NO_XML): Update now that the
conflict report can produce a "warnings being treated as errors"
message. Also, check that stderr is now fully scrubbed by -Wnone
when the exit status is 0.
(cherry picked from commit 6f8bdce25d)
Thus, conflict reports are now affected by -Werror and -Wnone
(unless %expect or %expect-rr is specified). Reported by George
Neuner at
<http://lists.gnu.org/archive/html/bug-bison/2010-08/msg00002.html>.
* NEWS (2.5): Document.
* doc/bison.texinfo (Bison Options): Document.
* src/complain.c, src/complain.h (set_warning_issued): Export
function.
* src/conflicts.c (conflicts_print): Suppress conflict report
based on -Wno-conflicts-sr and -Wno-conflicts-rr, and treat
conflicts as errors if -Werror.
* src/getargs.c (warnings_flag): Initialize with
warnings_conflicts_sr and warnings_conflicts_rr as well.
(warnings_args, warnings_types): Add entries for
warnings_conflicts_sr and warnings_conflicts_rr.
(usage): Update.
* src/getargs.h (enum warnings): Add entries for
warnings_conflicts_sr and warnings_conflicts_rr.
* tests/conflicts.at (-W versus %expect and %expect-rr): New test
group.
* tests/local.at (AT_BISON_CHECK_NO_XML): Update now that the
conflict report can produce a "warnings being treated as errors"
message. Also, check that stderr is now fully scrubbed by -Wnone
when the exit status is 0.
Unfortunately it is not possible to reuse the %prec directive. This
is because to please POSIX, we do not require to end the rules with a
semicolon. As a result,
foo: bar %prec baz
is ambiguous: either a rule which precedence is that of baz, or a rule,
and then a declaration of the precedence of the token baz.
* doc/bison.texinfo: Document %precedence.
(Precedence Only): New.
* src/assoc.h, src/assoc.c (precedence_assoc): New.
* src/conflicts.c (resolve_sr_conflict): Support it.
* src/scan-gram.l, src/parse-gram.y (%precedence): New token.
Parse it.
* tests/calc.at: Use %precedence for NEG.
* tests/conflicts.at (%precedence does not suffice)
(%precedence suffices): New tests.
* data/xslt/xml2dot.xsl (xsl:template match="rule"): Use a ` '
instead of a `\n'. That is, don't add escapes yet or they'll be doubly
escaped later.
(xsl:template name="output-node"): Use the new escape template instead
of the string-replace template directly.
(xsl:template name="output-edge"): Likewise.
(xsl:template name="escape"): New, escapes backslashes and newlines in
addition to quotation marks.
* src/graphviz.c (start_graph, output_node, output_edge): Add
whitespace to output for legibility.
Make xml2text.xsl and --report produce the same output, and remove the
XML "conflicts" element since a conflict summary is easily extracted
from the automaton.
* data/xslt/bison.xsl: New.
(xsl:template match="state" mode="bison:count-conflicts): New.
* data/xslt/xml2text.xsl: Import bison.xsl.
(xsl:template match="bison-xml-report"): Instead of styling the
"conflicts" element, style the "automaton" element with mode
"conflicts". Unlike the former, the latter lists S/R and R/R
conflicts for a state on the same line.
(xsl:template match="conflicts"): Remove.
(xsl:template match="conflict"): Remove.
(xsl:template match="terminal"): Line-wrap the list of rules in which
the terminal is used.
(xsl:template match="nonterminal"): Likewise for nonterminals.
(xsl:template match="automaton" mode="conflicts"): New.
(xsl:template match="state" mode="conflicts"): New.
(xsl:template name="line-wrap"): New.
(xsl:template name="ws-search"): New.
* data/xslt/xml2xhtml.xsl: Import bison.xsl.
(xsl:template match="bison-xml-report"): Instead of styling the
"conflicts" element, style the "automaton" element with mode
"conflicts."
(xsl:template match="conflicts"): Remove.
(xsl:template match="conflict"): Remove.
(xsl:template match="automaton" mode="conflicts"): New.
(xsl:template match="state" mode="conflicts): New.
* src/conflicts.c (conflicts_output_xml): Remove.
* src/conflicts.h (conflicts_output_xml): Remove prototype.
* src/print-xml.c (print_xml): Don't invoke conflicts_output_xml.
* src/print.c (print_grammar): Consistently wrap at the 66th column so
the corresponding XSLT is easier. Also, never wrap between a word and
the comma that follows it.
Problem reported by Wojciech Polak.
* src/print-xml.c (xml_puts): Work even if LEVEL exceeds INT_MAX/2.
(xml_printf): Undo change I made on 21 September; that is,
indent 2 spaces, not 1.
elsewhere.
* src/print-xml.c: Prefer "const" after types; that's more consistent.
(xml_printf): Indent just 1 space for level.
(e_char, xlate_char): Remove.
(xml_escape_string): Rewrite to avoid undefined behavior (used
storage that was freed from the stack).
(xml_escape_n): Don't bother checking for subscript error.
2007-09-21 Wojciech Polak <polak@gnu.org>
Add support for an -x option to generate an XML report.
It is not documented yet.
* src/print-xml.c: New file.
* src/print-xml.h: Likewise.
* lib/timevar.def (TV_XML): New var.
* src/Makefile.am (bison_SOURCES): Add print-xml.c, print-xml.h.
* src/conflicts.c: Include print-xml.h.
(solved_conflicts_xml_obstack): New var.
(log_resolution, conflicts_solve, conflicts_free):
Add support for XML report.
(conflicts_output_val): New function.
* src/conflicts.h (conflicts_output_val): New decl.
* src/files.c (spec_xml_file): New var.
(compute_output_file_names, output_file_names_free): Add XML support.
* src/files.h (spec_xml_file): New decl.
* src/getargs.c (xml_flag): New var.
(usage, short_options, long_options, getargs): Add XML support.
* src/getargs.h (xml_flag): New decl.
* src/gram.c: Include print-xml.h.
(rule_lhs_print_xml, rule_rhs_print_xml):
(grammar_rules_partial_print_xml, grammar_rules_print_xml):
New functions.
* src/gram.h: Declare external ones.
* src/main.c: Include print-xml.h.
(main): Add XML support.
* src/reduce.c: Include print-xml.h.
(reduce_xml): New function.
* src/reduce.h: Declare it.
* src/state.c: Include print-xml.h.
(state_new): Add XML support.
(state_rule_lookahead_tokens_print_xml): New function.
* src/state.h: Declare it.
(struct state): New member solved_conflicts_xml.
* src/symtab.c (symbol_class_get_string): New function.
* src/symtab.h: Declare it.
2007-09-21 Paul Eggert <eggert@cs.ucla.edu>
conflicts involving multiple reductions.
* src/conflicts.c (resolve_sr_conflict): Don't assign the error action
set for a state here or Bison will abort if it is reassigned on a
later conflicted reduction in the same state.
Similarly, don't finalize and assign the solved conflicts report here
or it will be lost if it is reassigned on a later conflicted reduction
in the same state.
(set_conflicts): Instead, assign them both here after all S/R conflicts
in the state have been fully examined.
* src/print.c (shift_set): Rename to...
(no_reduce_set): ... this.
(print_reductions): Update for rename, and add %nonassoc error action
tokens to no_reduce_set so that, when printing the first remaining
reduction on an error action token, the reduction is enclosed in
brackets.
(print_results): Update for rename.
* tests/conflicts.at (Solved conflicts report for multiple reductions
in a state): New test case.
(%nonassoc error actions for multiple reductions in a state): New test
case.
* src/main.c (main): Don't depend on C99 features.
* src/conflicts.c (conflicts_update_state_numbers): Fix for-loop.
* src/lalr.c (lalr_update_state_numbers): Fix for-loop.
* src/reader.c (check_and_convert_grammar): Fix for-loop.
* src/state.c (state_mark_reachable_states): Fix for-loop.
(state_remove_unreachable_states): Fix for-loop.
Don't widen struct state with member reachable just to temporarily
record reachability. Instead, use a local bitset.
* src/state.h (struct state): Remove member.
* src/state.c (state_new): Don't initialize it.
(state_mark_reachable_states): Rename to...
(state_record_reachable_states): ... this, and use bitset.
(state_remove_unreachable_states): Use bitset.
