Add -Wother so -Wnone suppresses all warnings.

Reported by George Neuner at
<http://lists.gnu.org/archive/html/bug-bison/2010-08/msg00002.html>.
* NEWS (2.5): Document.
* THANKS (George Neuner): Add.
* doc/bison.texinfo (Bison Options): Document.
* src/complain.c, src/complain.h
(warn_at, warn_at_indent, warn): Suppress warning if -Wno-other.
(midrule_value_at): New warning function, similar to yacc_at in
that it's controlled by its own warning category.
* src/getargs.c (warnings_flag): Initialize to warnings_other.
(warnings_args, warnings_types): Add entry for warnings_other.
(usage): Update.
* src/getargs.h (enum warnings): Add entry for warnings_other.
* src/gram.c (grammar_rules_useless_report): If -Wno-other, then
don't print useless rules.
* src/reader.c (symbol_should_be_used): Rather than adjusting the
return value based on whether midrule value warnings are enabled,
accept a new parameter for telling the caller whether true is
being returned for a potential midrule warning.
(grammar_rule_check): Use midrule_value_at for midrule value
warnings, and continue to use warn_at for all other warnings.  Let
them check whether the warnings are enabled.
* tests/local.at (AT_BISON_CHECK): Update documentation.
(AT_BISON_CHECK_NO_XML): Check that -Wnone and --warnings=none
disable all warnings exercised in the test suite.
(cherry picked from commit 8ffd7912e3)

tests/local.at

@@ -247,8 +247,10 @@ $2])
 
 # AT_BISON_CHECK(BISON_ARGS, [OTHER_AT_CHECK_ARGS])
 # -------------------------------------------------
-# Check Bison by invoking `bison BISON_ARGS'.  OTHER_AT_CHECK_ARGS are the
-# usual remaining arguments to AT_CHECK: STATUS, STDOUT, etc.
+# Check Bison by invoking `bison BISON_ARGS'.  BISON_ARGS should not contain
+# shell constructs (such as redirection or pipes) that would prevent
+# appending additional command-line arguments for bison. OTHER_AT_CHECK_ARGS
+# are the usual remaining arguments to AT_CHECK: STATUS, STDOUT, etc.
 #
 # This macro or AT_BISON_CHECK_NO_XML should always be used whenever invoking
 # Bison in the test suite.  For now it ensures that:
@@ -262,6 +264,8 @@ $2])
 #
 #   3. If stderr contains a warning, -Werror and --warnings=error
 #      convert the warning to an error.
+#
+#   4. If stderr contains a warning, -Wnone and --warnings=none suppress it.
 m4_define([AT_BISON_CHECK],
 [m4_if(m4_quote($2), [0], [AT_BISON_CHECK_XML($@)],
        m4_quote($2), [], [AT_BISON_CHECK_XML($@)])
@@ -287,10 +291,16 @@ m4_if(m4_bregexp([$4], [: warning: ]), [-1], [],
               if test -f experr; then
                 mv experr at-bison-check-experr.bak
               fi
+              if test -f expout; then
+                mv expout at-bison-check-expout.bak
+              fi
+
+              # To avoid expanding it repeatedly, store specified stdout.
+              ]AT_DATA([expout], [$3])[
 
               # Run with -Werror.
-              ]AT_CHECK(AT_QUELL_VALGRIND[[ bison -Werror ]$1],
-                        [[1]], [$3], [stderr])[
+              ]AT_CHECK(AT_QUELL_VALGRIND[[ bison ]$1[ -Werror]],
+                        [[1]], [expout], [stderr])[
 
               # Build expected stderr up to and including the "warnings
               # being treated as errors" message.
@@ -322,10 +332,21 @@ m4_if(m4_bregexp([$4], [: warning: ]), [-1], [],
 
               # Now check --warnings=error.
               cp stderr experr
-              ]AT_CHECK(AT_QUELL_VALGRIND[[ bison --warnings=error ]$1],
-                        [[1]], [$3], [experr])[
+              ]AT_CHECK(AT_QUELL_VALGRIND[[ bison ]$1[ --warnings=error]],
+                        [[1]], [expout], [experr])[
+
+              # Now check -Wnone and --warnings=none by making sure that
+              # -Werror doesn't change the exit status when -Wnone or
+              # --warnings=none is specified.
+              ]AT_CHECK(AT_QUELL_VALGRIND[[ bison ]$1[ -Wnone -Werror]],
+                        [[0]], [expout], [ignore])[
+              ]AT_CHECK(AT_QUELL_VALGRIND[[ bison ]$1[ --warnings=none \
+                        -Werror]], [[0]], [expout], [ignore])[
 
               # Restore caller's files.
+              if test -f at-bison-check-expout.bak; then
+                mv at-bison-check-expout.bak expout
+              fi
               if test -f at-bison-check-experr.bak; then
                 mv at-bison-check-experr.bak experr
               fi