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."
The previous name is too obscure, and the other macros for C++ use
CXX, not CC.
* tests/local.at (AT_SKEL_CC_IF, AT_SKEL_JAVA_IF): Rename as...
(AT_CXX_IF, AT_JAVA_IF): these.
Adjust callers.
On these tests, at -O2 and above, GCC 8 complains that yylval may be
uninitialized. But it seems wrong: it is initialized. Rather than
turning off the warning in the skeleton (hence possibility hiding
relevant warnings of user parsers), let's turn it off in the tests
only.
163: parse.error=verbose and consistent errors: FAILED (conflicts.at:625)
165: parse.error=verbose and consistent errors: lr.default-reduction=consistent FAILED (conflicts.at:635)
166: parse.error=verbose and consistent errors: lr.default-reduction=accepting FAILED (conflicts.at:641)
167: parse.error=verbose and consistent errors: lr.type=canonical-lr FAILED (conflicts.at:645)
168: parse.error=verbose and consistent errors: parse.lac=full FAILED (conflicts.at:650)
169: parse.error=verbose and consistent errors: parse.lac=full lr.default-reduction=accepting FAILED (conflicts.at:655)
We get:
input.c: In function 'yyparse':
input.c:980:9: error: 'yylval' may be used uninitialized in this function [-Werror=maybe-uninitialized]
YYSTYPE yylval YY_INITIAL_VALUE (= yyval_default);
^~~~~~
cc1: all warnings being treated as errors
See https://lists.gnu.org/archive/html/bison-patches/2018-08/msg00063.html.
* tests/conflicts.at (AT_CONSISTENT_ERRORS_CHECK): Disable
-Wmaybe-uninitialized.
* tests/conflicts.at (AT_CONSISTENT_ERRORS_CHECK): Move AT_SETUP/AT_CLEANUP
into it, so that we don't skip non Java tests following a test case in Java.
* src/symtab.c (symbol_precedence_set): Use prec_location, not
location (which is the first occurrence of the symbol, possibly just
%token).
Also, as redefinitions are not allowed, keep the first values, not
the subsequent ones.
* tests/conflicts.at, tests/existing.at, tests/regression.at: Adjust.
In a precedence declaration, when tokens are declared with a litteral
character (e.g., 'a') or with a identifier (e.g., B), Bison behaved
differently: the litteral tokens would be numbered first, and then the
other ones, leading to the following grammar:
%right A B 'c' 'd'
being numbered as such: 'c' 'd' A B.
* src/parse-gram.y (symbol.prec): Set the symbol number when reading the
symbols.
* tests/conflicts.at (Token declaration order: literals vs. identifiers):
New.
Signed-off-by: Akim Demaille <akim@lrde.epita.fr>
* src/gram.c (grammar_rules_useless_report): Let -fcaret handle the
pretty-printing of the guilty rules.
(rule_print): Inline in its only use.
* tests/conflicts.at, tests/existing.at, tests/reduce.at,
* tests/regression.at: Adjust.
* NEWS: Document.
The new warning category "precedence" flags useless precedence and
associativity. -Wprecedence can now be used, it is disabled by default.
The warnings about precedence and associativity are grouped into one, and
the testsuite was corrected accordingly.
* src/complain.h (warnings): Introduce "precedence".
* src/complain.c (warnings_print_categories): Adjust.
* src/getargs.c (warnings_args, warning_types): Likewise.
* src/symtab.h, src/symtab.c (print_associativity_warnings): Remove.
* src/symtab.h (register_assoc): Correct arguments.
* src/symtab.c (print_precedence_warnings): Print both warnings together.
* doc/bison.texi (Bison options): Document the warnings and provide an
example.
* tests/conflicts.at, tests/existing.at, tests/local.at,
* tests/regression.at: Adapt the testsuite for the new category
(-Wprecedence instead of -Wother where appropriate).
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.
* cfg.mk: Ignore strcmp in local.at.
* tests/conflicts.at: Use AT_PARSER_CHECK.
* tests/regression.at: Preserve the exit status of the generated parsers.
* tests/local.mk ($(TESTSUITE)): Map @tb@ to a tabulation.
* tests/c++.at, tests/input.at, tests/regression.at: Use @tb@.
* cfg.mk: (space-tab): There are no longer exceptions.
* origin/maint:
misc: pacify the Tiny C Compiler
cpp: make the check of Flex version portable
misc: require getline
c++: support wide strings for file names
doc: document carets
tests: enhance existing tests with carets
errors: show carets
getargs: add support for --flags/-f
Conflicts:
doc/bison.texi
m4/.gitignore
src/complain.c
src/flex-scanner.h
src/getargs.c
src/getargs.h
src/gram.c
src/main.c
tests/headers.at
* tests/actions.at: Unset value.
* tests/conflicts.at: Rule useless due to conflicts.
* tests/input.at: Missing terminator, unexpected end of file, command line
redefinition of variable.
* tests/named-refs.at: Many errors.
* tests/reduce.at: Useless nonterminals and rules.
* tests/regression.at: Large token.
* origin/maint:
tests: close files in glr-regression
xml: match DOT output and xml2dot.xsl processing
xml: factor xslt space template
graph: fix a memory leak
xml: documentation
output: capitalize State
This improves readability. This is also what gcc does.
* NEWS: Document this change.
* src/complain.c (complain_at): Prefix all errors with "error: ".
(complain_at_indent, warn_at_indent): Do not prefix the context
information of errors, which are basically just indented errors.
* tests/conflicts.at, tests/glr-regression.at, tests/input.at,
tests/named-refs.at, tests/output.at, tests/push.at,
tests/regression.at, tests/skeletons.at: Apply this change.
Signed-off-by: Akim Demaille <akim@lrde.epita.fr>
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.
* origin/maint:
tests: use the generalized default yylex.
tests: AT_YYERROR_DEFINE: prepare for list of ints.
skeletons: no longer define YYLSP_NEEDED.
c++: do not export YYTOKEN_TABLE and YYERROR_VERBOSE.
Conflicts:
data/c.m4
data/glr.cc
data/lalr1.cc
doc/bison.texi
tests/regression.at
* origin/maint:
tests: do not output m4 set up.
tests: use the generic yyerror function.
tests: use assert instead of plain abort.
tests: improve the generic yylex implementation.
tests: generalize the compilation macros.
tests: fix confusion between api.prefix and name-prefix.
maint: gitignores.
yacc: work around the ylwrap limitation.
Conflicts:
NEWS
tests/local.at
* origin/maint:
maint: formatting changes.
tests: support api.prefix.
tests: pacify font-lock-mode.
tests: remove test covered elsewhere.
tests: factor the declaration/definition of yyerror and yylex.
regen.
tests: portability issues.
tests: call the parser from another compilation unit.
glr.c, yacc.c: declare yydebug in the header.
skeletons: use header guards.
tests: improve AT_FULL_COMPILE.
tests: reorder.
tests: strengthen the test on generated headers inclusion
yacc.c: instead of duplicating y.tab.h inside y.tac.c, include it.
yacc.c: factor.
Conflicts:
NEWS
data/glr.c
data/yacc.c
src/parse-gram.c
src/parse-gram.h
tests/conflicts.at
tests/regression.at
* cfg.mk: Skip bison generated files, 2.5 is generating trailing
blanks. This is already fixed in master.
* tests/conflicts.at, tests/java.at: Fix white space issues.
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.
LAC = lookahead correction. See discussion at
<http://lists.gnu.org/archive/html/bison-patches/2009-09/msg00034.html>.
However, one point there must be corrected: because of %nonassoc,
LAC is *not* always redundant for lr.type=canonical-lr.
* data/yacc.c: Accept values of "none" (default) or "full" for
parse.lac. Accept %define parse.lac.es-capacity to specify
capacity of LAC's temporary exploratory stack. It defaults to 20
and, for now, will not grow dynamically.
(b4_lac_flag, b4_lac_if): New m4 macros. Evaluate as true for
parse.lac!=none.
(YYBACKUP): Invoke YY_LAC_DISCARD.
(YY_LAC_ESTABLISH, YY_LAC_DISCARD): New cpp macros that invoke
yy_lac and track when it needs to be invoked
(yy_lac): New function that, given the current stack, determines
whether a token can eventually be shifted. Return status mimics
yyparse return status.
(yysyntax_error): Change yystate argument to yyssp so stack top
can be passed to yy_lac. If LAC is requested, build expected
token list by invoking yy_lac for every token instead of just
checking the current state for lookaheads. Return 2 if yy_lac
exhausts memory.
(yyparse, yypush_parse): Use local variable yy_lac_established and
cpp macros YY_LAC_ESTABLISH and YY_LAC_DISCARD to implement LAC.
Update yysyntax_error invocation. Add yyexhaustedlab code if LAC
is requested.
* tests/conflicts.at (%nonassoc and eof): Extend to check the
effect of each of -Dlr.type=canonical-lr and -Dparse.lac=full.
(%error-verbose and consistent errors): Likewise.
(LAC: %nonassoc requires splitting canonical LR states): New test
group demonstrating how LAC can fix canonical LR.
* tests/input.at (LAC: Errors for %define): New test group.
* tests/regression.at (LAC: Exploratory stack): New test group.
(LAC: Memory exhaustion): New test group.
(cherry picked from commit bf35c71c58)
Conflicts:
src/parse-gram.c
src/parse-gram.h
