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[PATCH] -Werror: fix for rules useless in parser after conflicts.
From: |
Joel E. Denny |
Subject: |
[PATCH] -Werror: fix for rules useless in parser after conflicts. |
Date: |
Sun, 1 Aug 2010 23:36:29 -0400 (EDT) |
User-agent: |
Alpine 1.00 (DEB 882 2007-12-20) |
I am thinking of including this patch in bison 2.4.3. I wrote it while
considering a complaint on comp.compilers saying that -Werror doesn't
work:
http://compilers.iecc.com/comparch/article/10-07-039
As far as I can tell, the only warning on which -Werror has no effect is
the warning that a rule is useless in the parser due to conflicts.
Because bison explicitly labels these messages as warnings, I see this
behavior as a bug, and this patch fixes it. But is there any backward
compatibility problem to consider here?
Now thinking beyond 2.4.3, the only specific case of -Werror not working
that was mentioned on comp.compilers is the case of R/R conflicts. Bison
currently does not label R/R conflict messages as warnings, so it is not
as clear in this case that -Werror should have any effect. Would treating
parser conflicts as warnings be too contrary to traditional yacc/bison
thinking? Besides, bison already supports %error and %error-rr to turn
them into errors. On the other hand, it seems that any diagnostic printed
on stderr is at least a warning, and I can see how the user might
appreciate a guarantee that -Werror will prevent him from missing any such
diagnostic. That seems to be the thinking at comp.compilers. Opinions?
>From 954474bfa1a875eeefe9aa1989d9c7be6f64726b Mon Sep 17 00:00:00 2001
From: Joel E. Denny <address@hidden>
Date: Sun, 1 Aug 2010 18:51:46 -0400
Subject: [PATCH] -Werror: fix for rules useless in parser after conflicts.
* NEWS (2.4.3): Document fix.
* src/complain.c (error_message): Extend to handle incomplete
error messages so warn and warn_at can be used in more cases.
* src/gram.c (grammar_rules_useless_report): Use warn_at so that
-Werror is always obeyed.
* src/reduce.c (reduce_print): Use warn so that the "warnings
being treated as errors" message is printed consistently before
the first warning message. This makes testing easier.
* tests/local.at (AT_BISON_WERROR_MSG): New macro.
(AT_BISON_CHECK_NO_XML): Extend to check -Werror and
--warnings=error when warnings appear in bison's stderr.
---
ChangeLog | 15 +++++++++++++
NEWS | 3 ++
src/complain.c | 14 +++++++++--
src/gram.c | 9 ++++---
src/reduce.c | 24 +++++++-------------
tests/local.at | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
6 files changed, 106 insertions(+), 24 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 15c236e..d365830 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+2010-08-01 Joel E. Denny <address@hidden>
+
+ -Werror: fix for rules useless in parser after conflicts.
+ * NEWS (2.4.3): Document fix.
+ * src/complain.c (error_message): Extend to handle incomplete
+ error messages so warn and warn_at can be used in more cases.
+ * src/gram.c (grammar_rules_useless_report): Use warn_at so that
+ -Werror is always obeyed.
+ * src/reduce.c (reduce_print): Use warn so that the "warnings
+ being treated as errors" message is printed consistently before
+ the first warning message. This makes testing easier.
+ * tests/local.at (AT_BISON_WERROR_MSG): New macro.
+ (AT_BISON_CHECK_NO_XML): Extend to check -Werror and
+ --warnings=error when warnings appear in bison's stderr.
+
2010-07-29 Joel E. Denny <address@hidden>
maint: enable gnits only at stable releases.
diff --git a/NEWS b/NEWS
index 2ab2250..64a1ee6 100644
--- a/NEWS
+++ b/NEWS
@@ -3,6 +3,9 @@ Bison News
* Changes in version 2.4.3 (????-??-??):
+** Bison now obeys -Werror and --warnings=error for warnings about
+ grammar rules that are useless in the parser due to conflicts.
+
** Problems with spawning M4 on at least FreeBSD 8 and FreeBSD 9 have
been fixed.
diff --git a/src/complain.c b/src/complain.c
index 4266af1..496924a 100644
--- a/src/complain.c
+++ b/src/complain.c
@@ -37,7 +37,10 @@ bool complaint_issued;
* \param loc the location, defaulting to the current file,
* or the program name.
* \param prefix put before the message (e.g., "warning").
- * \param message the error message, a printf format string.
+ * \param message the error message, a printf format string. Iff it
+ * ends with ": ", then no trailing newline is printed,
+ * and the caller should print the remaining
+ * newline-terminated message to stderr.
* \param args the arguments of the format string.
*/
static
@@ -56,8 +59,13 @@ error_message (location *loc,
fprintf (stderr, "%s: ", prefix);
vfprintf (stderr, message, args);
- putc ('\n', stderr);
- fflush (stderr);
+ {
+ size_t l = strlen (message);
+ if (l < 2 || message[l-2] != ':' || message[l-1] != ' ') {
+ putc ('\n', stderr);
+ fflush (stderr);
+ }
+ }
}
/** Wrap error_message() with varargs handling. */
diff --git a/src/gram.c b/src/gram.c
index 81939b6..2962d98 100644
--- a/src/gram.c
+++ b/src/gram.c
@@ -23,11 +23,12 @@
#include <quotearg.h>
+#include "complain.h"
#include "gram.h"
+#include "print-xml.h"
#include "reader.h"
#include "reduce.h"
#include "symtab.h"
-#include "print-xml.h"
/* Comments for these variables are in gram.h. */
@@ -307,9 +308,9 @@ grammar_rules_useless_report (const char *message)
for (r = 0; r < nrules ; ++r)
if (!rules[r].useful)
{
- location_print (stderr, rules[r].location);
- fprintf (stderr, ": %s: %s: ", _("warning"), message);
- rule_print (&rules[r], stderr);
+ warn_at (rules[r].location, "%s: ", message);
+ rule_print (&rules[r], stderr);
+ fflush (stderr);
}
}
diff --git a/src/reduce.c b/src/reduce.c
index 4cec048..6e16ce3 100644
--- a/src/reduce.c
+++ b/src/reduce.c
@@ -383,23 +383,15 @@ static void
reduce_print (void)
{
if (nuseless_nonterminals > 0)
- {
- fprintf (stderr, "%s: %s: ", grammar_file, _("warning"));
- fprintf (stderr, ngettext ("%d nonterminal useless in grammar",
- "%d nonterminals useless in grammar",
- nuseless_nonterminals),
- nuseless_nonterminals);
- fprintf (stderr, "\n");
- }
+ warn (ngettext ("%d nonterminal useless in grammar",
+ "%d nonterminals useless in grammar",
+ nuseless_nonterminals),
+ nuseless_nonterminals);
if (nuseless_productions > 0)
- {
- fprintf (stderr, "%s: %s: ", grammar_file, _("warning"));
- fprintf (stderr, ngettext ("%d rule useless in grammar",
- "%d rules useless in grammar",
- nuseless_productions),
- nuseless_productions);
- fprintf (stderr, "\n");
- }
+ warn (ngettext ("%d rule useless in grammar",
+ "%d rules useless in grammar",
+ nuseless_productions),
+ nuseless_productions);
}
void
diff --git a/tests/local.at b/tests/local.at
index 6ce7c7e..0ea4f9b 100644
--- a/tests/local.at
+++ b/tests/local.at
@@ -204,11 +204,17 @@ $2])
#
# 2. In the case of maintainer-xml-check, XML/XSLT output is compared with
# --graph and --report=all output for every working grammar.
+#
+# 3. If stderr contains a warning, -Werror and --warnings=error
+# convert the warning to an error.
m4_define([AT_BISON_CHECK],
[m4_if(m4_quote($2), [0], [AT_BISON_CHECK_XML($@)],
m4_quote($2), [], [AT_BISON_CHECK_XML($@)])
AT_BISON_CHECK_NO_XML($@)])
+m4_define([AT_BISON_WERROR_MSG],
+ [[bison: warnings being treated as errors]])
+
# AT_BISON_CHECK_NO_XML(BISON_ARGS, [OTHER_AT_CHECK_ARGS])
# --------------------------------------------------------
# Same as AT_BISON_CHECK except don't perform XML/XSLT checks. This is useful
@@ -216,7 +222,64 @@ AT_BISON_CHECK_NO_XML($@)])
# handle.
m4_define([AT_BISON_CHECK_NO_XML],
[AT_CHECK(m4_if(m4_quote($2), [0], [], m4_quote($2), [], [],
- [AT_QUELL_VALGRIND ])[[bison ]]$@)])
+ [AT_QUELL_VALGRIND ])[[bison ]]$@)
+m4_if(m4_bregexp([$4], [: warning: ]), [-1], [],
+ [m4_if(m4_quote(m4_if(m4_quote($2), [], [0], [$2])), [0],
+ [[# Don't interfere with caller's files.
+ if test -f stderr; then
+ mv stderr at-bison-check-stderr.bak
+ fi
+ if test -f experr; then
+ mv experr at-bison-check-experr.bak
+ fi
+
+ # Run with -Werror.
+ ]AT_CHECK(AT_QUELL_VALGRIND[[ bison -Werror ]$1],
+ [[1]], [$3], [stderr])[
+
+ # Build expected stderr up to and including the "warnings
+ # being treated as errors" message.
+ ]AT_DATA([[at-bison-check-warnings]], [$4])[
+ at_bison_check_first="` \
+ sed -n '/: warning: /=' at-bison-check-warnings \
+ | sed -n 1p \
+ `"
+ if test $at_bison_check_first -gt 1; then
+ sed -n "1,`expr $at_bison_check_first - 1`"p \
+ at-bison-check-warnings > experr
+ fi
+ echo ']AT_BISON_WERROR_MSG[' >> experr
+
+ # Finish building expected stderr and check. Unlike
+ # warnings, complaints cause bison to exit early. Thus,
+ # with -Werror, bison does not necessarily report all
+ # warnings that it does without -Werror, but it at least
+ # reports one.
+ at_bison_check_last="`sed -n '$=' stderr`"
+ if test x"$at_bison_check_last" = x; then
+ at_bison_check_last=1
+ fi
+ at_bison_check_last="`expr $at_bison_check_last - 1`"
+ sed -n "$at_bison_check_first,$at_bison_check_last"p \
+ at-bison-check-warnings >> experr
+ ]AT_CHECK([[sed 's,.*/\(]AT_BISON_WERROR_MSG[\)$,\1,' \
+ stderr 1>&2]], [[0]], [[]], [experr])[
+
+ # Now check --warnings=error.
+ cp stderr experr
+ ]AT_CHECK(AT_QUELL_VALGRIND[[ bison --warnings=error ]$1],
+ [[1]], [$3], [experr])[
+
+ # Restore caller's files.
+ if test -f at-bison-check-experr.bak; then
+ mv at-bison-check-experr.bak experr
+ fi
+ if test -f at-bison-check-stderr.bak; then
+ mv at-bison-check-stderr.bak stderr
+ fi
+ ]])
+ ])
+])
# AT_BISON_CHECK_XML(BISON_ARGS, [OTHER_AT_CHECK_ARGS])
# -----------------------------------------------------
--
1.7.0.4
- [PATCH] -Werror: fix for rules useless in parser after conflicts.,
Joel E. Denny <=