Currently the suggestion to rerun is a -Wother warning:
warning: 2 shift/reduce conflicts [-Wconflicts-sr]
warning: rerun with option '-Wcounterexamples' to generate conflict counterexamples [-Wother]
Instead, let's attach it as a subnote of the diagnostic (in the
current case, -Wconflicts-sr):
warning: 2 shift/reduce conflicts [-Wconflicts-sr]
note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
* src/conflicts.c (conflicts_print): Do that.
Adjust the test suite.
And let --report=all include the counterexamples.
* src/getargs.h, src/getargs.c (report_cex): New.
* src/main.c: Compute counterexamples when -rcex is specified.
* src/print.c: Include the counterexamples when -rcex is specified.
* tests/conflicts.at, tests/existing.at, tests/local.at: Adjust.
Suggesting -Wcounterexamples when there are conflicts is probably not
what the user wants. If she knows her conflicts and has set
%expect/%expect-rr appropriately, we shouldn't warn.
The commit also swaps the counterexamples and the report of conflicts,
into, IMHO, a more natural order: from
Shift/reduce conflict on token B:
1: 3 a: A .
1: 8 y: A . B
Example A • B C
First derivation s ::=[ a ::=[ A • ] x ::=[ B C ] ]
Example A • B C
Second derivation s ::=[ y ::=[ A • B ] c ::=[ C ] ]
input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
to
input.y: warning: 1 shift/reduce conflict [-Wconflicts-sr]
Shift/reduce conflict on token B:
1: 3 a: A .
1: 8 y: A . B
Example A • B C
First derivation s ::=[ a ::=[ A • ] x ::=[ B C ] ]
Example A • B C
Second derivation s ::=[ y ::=[ A • B ] c ::=[ C ] ]
input.y:4.4: warning: rule useless in parser due to conflicts [-Wother]
* src/conflicts.c (rule_conflicts_print): Rename as...
(report_rule_expectation_mismatches): this.
Move the handling of report_counterexamples to...
(conflicts_print): Here.
Display this warning when applicable.
AIX 7.1 supports diff -u, but its output does not match the expected
one.
Reported by Bruno Haible.
https://lists.gnu.org/r/bug-bison/2020-05/msg00049.html
* tests/atlocal.in (DIFF_U_WORKS): New.
* tests/local.at (AT_DIFF_U_CHECK): New.
* tests/existing.at (_AT_TEST_EXISTING_GRAMMAR): Use AT_DIFF_U_CHECK.
The "identifier and colon" of a rule is implemented as a single token,
but whose location is only that of the identifier (so that messages
about the lhs of a rule are accurate). When reducing empty rules, the
default location is the single point location on the end of the
previous symbol. As a consequence, when Bison parses a grammar, the
location of the right-hand side of an empty rule is based on the
lhs, *independently of the position of the colon*. And the colon can
be way farther, separated by comments, white spaces, including empty
lines.
As a result, some messages look really bad. For instance:
$ cat foo.y
%%
foo : /* empty */
bar
: /* empty */
gives
$ bison -Wall foo.y
foo.y:2.4: warning: empty rule without %empty [-Wempty-rule]
2 | foo : /* empty */
| ^
foo.y:3.4: warning: empty rule without %empty [-Wempty-rule]
3 | bar
| ^
The carets are not at the right column, not even the right line.
This commit passes the colon "again" after the "id colon" token, which
gives more accurate locations for these messages:
$ bison -Wall foo.y
foo.y:2.10: warning: empty rule without %empty [-Wempty-rule]
2 | foo : /* empty */
| ^
foo.y:4.2: warning: empty rule without %empty [-Wempty-rule]
4 | : /* empty */
| ^
* src/scan-gram.l (SC_AFTER_IDENTIFIER): Rollback the colon, so that
we scan it again afterwards.
(INITIAL): Scan colons.
* src/parse-gram.y (COLON): New.
(rules): Parse the colon after the rule's id_colon (and possible
named reference).
* tests/actions.at, tests/conflicts.at, tests/diagnostics.at,
* tests/existing.at: Adjust.
The format is inconsistent. For instance most sections are
indented (including "Terminals unused in grammar" for instance), but
the sections "Terminals, with rules where they appear" and
"Nonterminals, with rules where they appear" are not. Let's indent
them. Also, these two sections try to wrap the output to avoid lines
too long. Yet we don't do that in the rest of the file, for instance
when listing the lookaheads of an item.
For instance in the case of Bison's parse-gram.output we go from:
Terminals, with rules where they appear
"end of file" (0) 0
error (256) 28 88
"string" <char*> (258) 9 13 16 17 20 23 24 109 116
[...]
Nonterminals, with rules where they appear
$accept (58)
on left: 0
input (59)
on left: 1, on right: 0
prologue_declarations (60)
on left: 2 3, on right: 1 3
prologue_declaration (61)
on left: 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 22 23 24
25 26 27 28 29, on right: 3
[...]
to
Terminals, with rules where they appear
"end of file" (0) 0
error (256) 28 88
"string" <char*> (258) 9 13 16 17 20 23 24 109 116
[...]
Nonterminals, with rules where they appear
$accept (58)
on left: 0
input (59)
on left: 1
on right: 0
prologue_declarations (60)
on left: 2 3
on right: 1 3
prologue_declaration (61)
on left: 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 22 23 24 25 26 27 28 29
on right: 3
[...]
* src/print.c (END_TEST): Remove.
(print_terminal_symbols): Don't try to wrap the output.
(print_nonterminal_symbols): Likewise.
Make two different lines for occurrences on the left, and occurrence
on the rhs of the rules.
Indent by 4 and 8, not 3.
* src/reduce.c (reduce_output): Indent by 4, not 3.
* tests/conflicts.at, tests/existing.at, tests/reduce.at,
* tests/regression.at, tests/report.at:
Adjust.
The code was already using midrule only, never mid_rule. This is
simpler to remember, and matches a similar change we made from
look-ahead to lookahead.
* NEWS, doc/bison.texi, src/reader.c, src/scan-code.h, src/scan-code.l
* tests/actions.at, tests/c++.at, tests/existing.at: here.
* 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.
* 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.
Recent changes (in 2.7) introduced a dependency on both FILE and
fprintf, which are "available" only in %debug mode. This was to
define yy_location_print_, which is used only in %debug mode by the
parser, but massively used by the test suite to output the locations
in yyerror.
Break this dependency: the test suite should define its own routines
to display the locations. Eventually Bison will provide the user with
a means to display locations, but not yet.
* data/c.m4 (b4_yy_location_print_define): Use YYFPRINTF instead of
fprintf directly.
* data/yacc.c (b4_yy_location_print_define): Invoke it only in %debug
mode, so that stdio.h is included (needed for FILE*), and YYFPRINTF
is defined.
* tests/local.at (AT_YYERROR_DECLARE, AT_YYERROR_DEFINE): Declare
and define location_print and LOCATION_PRINT.
* tests/actions.at, tests/existing.at, tests/glr-regression.at,
* tests/input.at, tests/named-refs.at, tests/regression.at: Adjust
to use them.
Fix the expected line numbers (as the prologue's length has changed).
* 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
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.
Using http://github.com/lyda/misspell-check, massage its
output into sed commands to perform the suggested changes.
Initially, I filtered out the THRU->Through changes, because
that failed to retain capitalization in the grammar token.
Instead, do this manually, beforehand:
sed -i s/THRU/THROUGH/ tests/existing.at
git ls-files|misspellings -f -|perl -nl \
-e '/^(.*?)\[(\d+)\]: (\w+) -> "(.*?)"$/ or next;' \
-e '($file,$n,$l,$r)=($1,$2,$3,$4); $q="'\''"; $r=~s/$q/$q\\$q$q/g;'\
-e 'print "sed -i $q${n}s!$l!$r!$q $file"'|bash
Empty unions are not accepted by the ISO C99 grammar or by at
least some versions of Sun Studio. Reported by Wolfgang S. Kechel
at
<http://lists.gnu.org/archive/html/bug-bison/2011-08/msg00003.html>.
* NEWS (2.5.1): Document fix.
* THANKS (Wolfgang S. Kechel): Add.
* tests/existing.at (GNU Cim Grammar)
(GNU pic (Groff 1.18.1) Grammar.): Remove empty %union.
(cherry picked from commit 7451638148)
Empty unions are not accepted by the ISO C99 grammar or by at
least some versions of Sun Studio. Reported by Wolfgang S. Kechel
at
<http://lists.gnu.org/archive/html/bug-bison/2011-08/msg00003.html>.
* NEWS (2.5.1): Document fix.
* THANKS (Wolfgang S. Kechel): Add.
* tests/existing.at (GNU Cim Grammar)
(GNU pic (Groff 1.18.1) Grammar.): Remove empty %union.
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.
