]> git.saurik.com Git - bison.git/blobdiff - tests/local.at
Merge remote-tracking branch 'origin/maint'
[bison.git] / tests / local.at
index c1fcd60f068e6bae5707c350b90ec678740b4c29..42040829a6a57b6ef3dab8820a0edc16ec36666e 100644 (file)
 m4_version_prereq([2.58])
 
 
+# m4_null_if(VAL, IF-TRUE, IF-FALSE)
+# ----------------------------------
+# If VAL evaluates to empty or 0, run IF-TRUE, otherwise IF-FALSE.
+m4_define([m4_null_if],
+[m4_case(m4_quote($1),
+         [0], [$2],
+         [],  [$2],
+         [$3])])
+
 ## ------------- ##
 ## Basic tests.  ##
 ## ------------- ##
@@ -29,7 +38,7 @@ m4_version_prereq([2.58])
 # Expect COUNT matches of the PERL-REGEXP in FILE.  The file is
 # taken in "slurp" mode, i.e., one can match end-of-lines.
 m4_define([AT_MATCHES_CHECK],
-[AT_CHECK([perl -0777 -ne '
+[AT_CHECK([$PERL -0777 -ne '
 my $count = 0;
 s{$2}{ ++$count; "" }gem;
 printf "$count\n";' $1], [0], [$3
@@ -44,6 +53,8 @@ m4_divert_text([PREPARE_TESTS],
 {
   for at_save_file in stderr experr expout
   do
+    test ! -f at-bison-check-$at_save_file.bak ||
+      as_fn_error 1 "fatal error: back-up on top of a back-up"
     test ! -f $at_save_file || mv $at_save_file at-bison-check-$at_save_file.bak
   done
 }
@@ -90,14 +101,15 @@ m4_popdef([AT_LOC_LAST_COLUMN])])
 # AT_BISON_OPTION_PUSHDEFS([BISON-OPTIONS])
 # -----------------------------------------
 m4_define([AT_BISON_OPTION_PUSHDEFS],
-[_AT_BISON_OPTION_PUSHDEFS($[1], $[2], [$1])])
+[m4_divert_text([KILL],
+                [_AT_BISON_OPTION_PUSHDEFS($[1], $[2], [$1])])])
 
 
 # _AT_BISON_OPTION_PUSHDEFS($1, $2, [BISON-OPTIONS])
 # --------------------------------------------------
 # This macro works around the impossibility to define macros
 # inside macros, because issuing `[$1]' is not possible in M4 :(.
-# This sucks hard, GNU M4 should really provide M5 like $$1.
+# This sucks hard, GNU M4 should really provide M5-like $$1.
 m4_define([_AT_BISON_OPTION_PUSHDEFS],
 [m4_if([$1$2], $[1]$[2], [],
        [m4_fatal([$0: Invalid arguments: $@])])dnl
@@ -107,6 +119,7 @@ m4_pushdef([AT_SKEL_CC_IF],
 [m4_bmatch([$3], [%language "[Cc]\+\+"\|%skeleton "[a-z0-9]+\.cc"], [$1], [$2])])
 m4_pushdef([AT_SKEL_JAVA_IF],
 [m4_bmatch([$3], [%language "[Jj][Aa][Vv][Aa]"\|%skeleton "[a-z0-9]+\.java"], [$1], [$2])])
+# The target language: "c", "c++", or "java".
 m4_pushdef([AT_LANG],
 [AT_SKEL_JAVA_IF([java],
                  [AT_SKEL_CC_IF([c++],
@@ -125,9 +138,16 @@ m4_pushdef([AT_LEXPARAM_IF],
 m4_pushdef([AT_LOCATION_IF],
 [m4_bmatch([$3], [%locations], [$1], [$2])])
 m4_pushdef([AT_LOCATION_TYPE_IF],
-[m4_bmatch([$3], [%define location_type], [$1], [$2])])
+[m4_bmatch([$3], [%define \(api\.location\.type\|location_type\)], [$1], [$2])])
 m4_pushdef([AT_PARAM_IF],
 [m4_bmatch([$3], [%parse-param], [$1], [$2])])
+# Comma-terminated list of formals parse-parameters.
+# E.g., %parse-param { int x } %parse-param {int y} -> "int x, int y, ".
+# FIXME: Support grouped parse-param.
+m4_pushdef([AT_PARSE_PARAMS])
+m4_bpatsubst([$3], [%parse-param { *\([^{}]*[^{} ]\) *}],
+             [m4_append([AT_PARSE_PARAMS], [\1, ])])
+
 m4_pushdef([AT_PURE_IF],
 [m4_bmatch([$3], [%define  *api\.pure\|%pure-parser],
            [m4_bmatch([$3], [%define  *api\.pure *"?false"?], [$2], [$1])],
@@ -140,49 +160,56 @@ m4_pushdef([AT_NAME_PREFIX],
 [m4_bmatch([$3], [\(%define api\.prefix\|%name-prefix\) ".*"],
            [m4_bregexp([$3], [\(%define api\.prefix\|%name-prefix\) "\([^""]*\)"], [\2])],
            [yy])])
+m4_pushdef([AT_TOKEN_CTOR_IF],
+[m4_bmatch([$3], [%define api.token.constructor], [$1], [$2])])
+m4_pushdef([AT_TOKEN_PREFIX],
+[m4_bmatch([$3], [%define api.token.prefix ".*"],
+           [m4_bregexp([$3], [%define api.token.prefix "\(.*\)"], [\1])])])
 m4_pushdef([AT_API_prefix],
 [m4_bmatch([$3], [%define api\.prefix ".*"],
            [m4_bregexp([$3], [%define api\.prefix "\([^""]*\)"], [\1])],
            [yy])])
+m4_pushdef([AT_API_PREFIX],
+[m4_toupper(AT_API_prefix)])
 # yyerror receives the location if %location & %pure & (%glr or %parse-param).
 m4_pushdef([AT_YYERROR_ARG_LOC_IF],
 [AT_GLR_OR_PARAM_IF([AT_PURE_AND_LOC_IF([$1], [$2])],
-                   [$2])])
+                    [$2])])
 # yyerror always sees the locations (when activated), except if
 # (yacc & pure & !param).  FIXME: This is wrong.  See the manual.
 m4_pushdef([AT_YYERROR_SEES_LOC_IF],
 [AT_LOCATION_IF([AT_YACC_IF([AT_PURE_IF([AT_PARAM_IF([$1], [$2])],
-                                       [$1])],
-                           [$1])],
-               [$2])])
+                                        [$1])],
+                            [$1])],
+                [$2])])
 
 # The interface is pure: either because %define api.pure, or because we
 # are using the C++ parsers.
 m4_pushdef([AT_PURE_LEX_IF],
 [AT_PURE_IF([$1],
-           [AT_SKEL_CC_IF([$1], [$2])])])
+            [AT_SKEL_CC_IF([$1], [$2])])])
 
 m4_pushdef([AT_YYSTYPE],
 [AT_SKEL_CC_IF([AT_NAME_PREFIX[::parser::semantic_type]],
-               [[YYSTYPE]])])
+               [AT_API_PREFIX[STYPE]])])
 m4_pushdef([AT_YYLTYPE],
 [AT_SKEL_CC_IF([AT_NAME_PREFIX[::parser::location_type]],
-               [[YYLTYPE]])])
+               [AT_API_PREFIX[LTYPE]])])
 
 
 AT_PURE_LEX_IF(
 [m4_pushdef([AT_LOC], [(*llocp)])
  m4_pushdef([AT_VAL], [(*lvalp)])
  m4_pushdef([AT_YYLEX_FORMALS],
-           [AT_YYSTYPE *lvalp[]AT_LOCATION_IF([, AT_YYLTYPE *llocp])])
+            [AT_YYSTYPE *lvalp[]AT_LOCATION_IF([, AT_YYLTYPE *llocp])])
  m4_pushdef([AT_YYLEX_ARGS],
-           [lvalp[]AT_LOCATION_IF([, llocp])])
+            [lvalp[]AT_LOCATION_IF([, llocp])])
  m4_pushdef([AT_USE_LEX_ARGS],
-           [(void) lvalp;AT_LOCATION_IF([(void) llocp])])
+            [(void) lvalp;AT_LOCATION_IF([(void) llocp])])
  m4_pushdef([AT_YYLEX_PRE_FORMALS],
-           [AT_YYLEX_FORMALS, ])
+            [AT_YYLEX_FORMALS, ])
  m4_pushdef([AT_YYLEX_PRE_ARGS],
-           [AT_YYLEX_ARGS, ])
+            [AT_YYLEX_ARGS, ])
 ],
 [m4_pushdef([AT_LOC], [[(]AT_NAME_PREFIX[lloc)]])
  m4_pushdef([AT_VAL], [[(]AT_NAME_PREFIX[lval)]])
@@ -201,12 +228,15 @@ AT_SKEL_CC_IF(
     [AT_LOC_PUSHDEF([begin.line], [begin.column], [end.line], [end.column])])],
   [AT_LOC_PUSHDEF([first_line], [first_column], [last_line], [last_column])])
 
+
+AT_GLR_IF([AT_KEYWORDS([glr])])
 ])# _AT_BISON_OPTION_PUSHDEFS
 
 
 # AT_BISON_OPTION_POPDEFS
 # -----------------------
 m4_define([AT_BISON_OPTION_POPDEFS],
+[m4_divert_text([KILL],
 [m4_popdef([AT_YYLEX_PRE_ARGS])
 m4_popdef([AT_YYLEX_PRE_FORMALS])
 m4_popdef([AT_USE_LEX_ARGS])
@@ -219,12 +249,16 @@ m4_popdef([AT_LOC])
 m4_popdef([AT_PURE_LEX_IF])
 m4_popdef([AT_YYERROR_SEES_LOC_IF])
 m4_popdef([AT_YYERROR_ARG_LOC_IF])
+m4_popdef([AT_API_PREFIX])
 m4_popdef([AT_API_prefix])
+m4_popdef([AT_TOKEN_PREFIX])
+m4_popdef([AT_TOKEN_CTOR_IF])
 m4_popdef([AT_NAME_PREFIX])
 m4_popdef([AT_GLR_OR_PARAM_IF])
 m4_popdef([AT_PURE_AND_LOC_IF])
 m4_popdef([AT_LOCATION_TYPE_IF])
 m4_popdef([AT_LOCATION_IF])
+m4_popdef([AT_PARSE_PARAMS])
 m4_popdef([AT_PARAM_IF])
 m4_popdef([AT_LEXPARAM_IF])
 m4_popdef([AT_YACC_IF])
@@ -235,7 +269,7 @@ m4_popdef([AT_SKEL_JAVA_IF])
 m4_popdef([AT_GLR_CC_IF])
 m4_popdef([AT_LALR1_CC_IF])
 m4_popdef([AT_DEFINES_IF])
-AT_LOC_POPDEF
+AT_LOC_POPDEF])dnl
 ])# AT_BISON_OPTION_POPDEFS
 
 
@@ -289,8 +323,11 @@ $2])
 # AT_YYLEX_PROTOTYPE
 # AT_YYLEX_DECLARE_EXTERN
 # AT_YYLEX_DECLARE
-# AT_YYLEX_DEFINE(INPUT-STRING, [ACTION])
-# ---------------------------------------
+# AT_YYLEX_DEFINE([INPUT], [ACTION])
+# ----------------------------------
+# INPUT can be empty, or in double quotes, or a list (in braces).
+# ACTION may compute yylval for instance, using "res" as token type,
+# and "toknum" as the number of calls to yylex (starting at 0).
 m4_define([AT_YYLEX_PROTOTYPE],
 [int AT_NAME_PREFIX[]lex (]AT_YYLEX_FORMALS[)[]dnl
 ])
@@ -304,16 +341,17 @@ m4_define([AT_YYLEX_DECLARE],
 ])
 
 m4_define([AT_YYLEX_DEFINE],
-[[#include <stdlib.h> /* abort */
+[[#include <assert.h>
 static
 ]AT_YYLEX_PROTOTYPE[
 {
-  static char const input[] = "$1";
+  ]m4_bmatch([$1], [^\(".*"\)?$],
+             [[static char const input[] = ]m4_default([$1], [""])],
+             [[static int const input[] = ]$1])[;
   static size_t toknum = 0;
   int res;
   ]AT_USE_LEX_ARGS[;
-  if (! (toknum < sizeof input))
-    abort ();
+  assert (toknum < sizeof input / sizeof input[0]);
   res = input[toknum++];
   ]$2[;]AT_LOCATION_IF([[
   ]AT_LOC_FIRST_LINE[ = ]AT_LOC_LAST_LINE[ = 1;
@@ -330,7 +368,7 @@ static
 # Must be called inside a AT_BISON_OPTION_PUSHDEFS/POPDEFS pair.
 m4_define([AT_YYERROR_FORMALS],
 [m4_case(AT_LANG,
-[c], [AT_YYERROR_ARG_LOC_IF([YYLTYPE *llocp, ])[const char *msg]])[]dnl
+[c], [AT_YYERROR_ARG_LOC_IF([AT_YYLTYPE *llocp, ])AT_PARSE_PARAMS [const char *msg]])[]dnl
 ])
 
 m4_define([AT_YYERROR_PROTOTYPE],
@@ -354,28 +392,21 @@ m4_define([AT_YYERROR_DEFINE],
 /* A C error reporting function.  */
 static
 ]AT_YYERROR_PROTOTYPE[
-{
-]AT_YYERROR_SEES_LOC_IF([[
-  fprintf (stderr, "%d.%d",
-           ]AT_LOC_FIRST_LINE[, ]AT_LOC_FIRST_COLUMN[);
-  if (]AT_LOC_FIRST_LINE[ != ]AT_LOC_LAST_LINE[)
-    fprintf (stderr, "-%d.%d",
-             ]AT_LOC_LAST_LINE[,  ]AT_LOC_LAST_COLUMN[ - 1);
-  else if (]AT_LOC_FIRST_COLUMN[ != ]AT_LOC_LAST_COLUMN[ - 1)
-    fprintf (stderr, "-%d",
-             ]AT_LOC_LAST_COLUMN[ - 1);
+{]m4_bpatsubst(m4_defn([AT_PARSE_PARAMS]),
+              [[^,]+[^A-Za-z_0-9]\([A-Za-z_][A-Za-z_0-9]*\), *], [
+  YYUSE(\1);])dnl
+AT_YYERROR_SEES_LOC_IF([[
+  YY_LOCATION_PRINT (stderr, ]AT_LOC[);
   fprintf (stderr, ": ");]])[
   fprintf (stderr, "%s\n", msg);
 }]],
 [c++], [[/* A C++ error reporting function.  */
 void
-]AT_NAME_PREFIX[::parser::error (const location_type& l, const std::string& m)
-{
-  (void) l;
-  std::cerr << ]AT_LOCATION_IF([l << ": " << ])[m << std::endl;
+]AT_NAME_PREFIX[::parser::error (]AT_LOCATION_IF([[const location_type& l, ]])[const std::string& m)
+{  std::cerr << ]AT_LOCATION_IF([l << ": " << ])[m << std::endl;
 }]],
 [java], [AT_LOCATION_IF([[public void yyerror (Calc.Location l, String s)
-  {
+{
     if (l == null)
       System.err.println (s);
     else
@@ -385,7 +416,8 @@ void
   public void yyerror (String s)
   {
     System.err.println (s);
-  }]])])dnl
+  }]])],
+[m4_fatal([$0: invalid language: ]AT_LANG)])dnl
 ])
 
 
@@ -395,6 +427,9 @@ void
 
 # AT_BISON_CHECK(BISON_ARGS, [OTHER_AT_CHECK_ARGS])
 # -------------------------------------------------
+# High-level routine that may call bison several times, under different
+# conditions.
+#
 # 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
@@ -415,12 +450,57 @@ void
 #
 #   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($2), [], [AT_BISON_CHECK_XML($@)])
+[m4_null_if([$2], [AT_BISON_CHECK_XML($@)])
 AT_BISON_CHECK_NO_XML($@)])
 
-m4_define([AT_BISON_WERROR_MSG],
-          [[bison: warnings being treated as errors]])
+# AT_BISON_CHECK_(BISON_ARGS, [OTHER_AT_CHECK_ARGS])
+# --------------------------------------------------
+# Low-level macro to run bison once.
+m4_define([AT_BISON_CHECK_],
+[AT_CHECK(AT_QUELL_VALGRIND[[ bison ]]$@)])
+
+
+# AT_BISON_CHECK_WARNINGS(BISON_ARGS, [OTHER_AT_CHECK_ARGS])
+# ----------------------------------------------------------
+# Check that warnings (if some are expected) are correctly
+# turned into errors with -Werror, etc.
+m4_define([AT_BISON_CHECK_WARNINGS],
+[m4_if(m4_bregexp([$4], [: warning: ]), [-1], [],
+      [m4_null_if([$2], [AT_BISON_CHECK_WARNINGS_($@)])])])
+
+m4_define([AT_BISON_CHECK_WARNINGS_],
+[[# Defining POSIXLY_CORRECT causes bison to complain if options are
+# added after the grammar file name, so skip these checks in that
+# case.
+if test "$POSIXLY_CORRECT_IS_EXPORTED" = false; then
+          ]AT_SAVE_SPECIAL_FILES[
+
+  # To avoid expanding it repeatedly, store specified stdout.
+  ]AT_DATA([expout], [$3])[
+
+  # Run with -Werror.
+  ]AT_BISON_CHECK_([$1[ -Werror]], [[1]], [expout], [stderr])[
+
+  # Build expected stderr up to and including the "warnings being
+  # treated as errors" message.
+  ]AT_DATA([[experr]], [$4])[
+  $PERL -pi -e 's{(.*): warning: (.*)\[-W(.*)\]$}
+                 {$][1: error: $][2\@<:@-Werror=$][3@:>@}' experr
+  ]AT_CHECK([[sed 's,.*/$,,' stderr 1>&2]], [[0]], [[]], [experr])[
+
+  # Now check --warnings=error.
+  cp stderr experr
+  ]AT_BISON_CHECK_([$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_BISON_CHECK_([$1[ -Wnone -Werror]], [[0]], [expout])[
+  ]AT_BISON_CHECK_([$1[ --warnings=none -Werror]], [[0]], [expout])[
+
+  ]AT_RESTORE_SPECIAL_FILES[
+fi]dnl
+])
 
 # AT_BISON_CHECK_NO_XML(BISON_ARGS, [OTHER_AT_CHECK_ARGS])
 # --------------------------------------------------------
@@ -428,70 +508,8 @@ m4_define([AT_BISON_WERROR_MSG],
 # when a tortured grammar's XML is known to be too large for xsltproc to
 # handle.
 m4_define([AT_BISON_CHECK_NO_XML],
-[AT_CHECK(m4_if(m4_quote($2), [0], [], m4_quote($2), [], [],
-                [AT_QUELL_VALGRIND ])[[bison ]]$@)
-m4_if(m4_bregexp([$4], [: warning: ]), [-1], [],
-      m4_quote(m4_if(m4_quote($2), [], [0], [$2])), [0], [[
-        # Defining POSIXLY_CORRECT causes bison to complain if options
-        # are added after the grammar file name, so skip these checks
-        # in that case.
-        if test -z "${POSIXLY_CORRECT+set}"; then
-          ]AT_SAVE_SPECIAL_FILES[
-
-          # To avoid expanding it repeatedly, store specified stdout.
-          ]AT_DATA([expout], [$3])[
-
-          # Run with -Werror.
-          ]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.
-          ]AT_DATA([[at-bison-check-warnings]], [$4])[
-          at_bison_check_first=`sed -n \
-            '/: warning: /{=;q;}' at-bison-check-warnings`
-          : ${at_bison_check_first:=1}
-          at_bison_check_first_tmp=`sed -n \
-            '/conflicts: [0-9].*reduce$/{=;q;}' at-bison-check-warnings`
-          : ${at_bison_check_first_tmp:=1}
-          if test $at_bison_check_first_tmp -lt $at_bison_check_first; then
-            at_bison_check_first=$at_bison_check_first_tmp
-          fi
-          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`
-          : ${at_bison_check_last:=1}
-          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 ]$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])[
-          ]AT_CHECK(AT_QUELL_VALGRIND[[ bison ]$1[ --warnings=none \
-                    -Werror]], [[0]], [expout])[
-
-          ]AT_RESTORE_SPECIAL_FILES[
-        fi
-      ]])
-])
+[AT_CHECK(m4_null_if([$2], [], [AT_QUELL_VALGRIND ])[[bison ]]$@)
+AT_BISON_CHECK_WARNINGS($@)])
 
 # AT_BISON_CHECK_XML(BISON_ARGS, [OTHER_AT_CHECK_ARGS])
 # -----------------------------------------------------
@@ -509,10 +527,10 @@ m4_define([AT_BISON_CHECK_XML],
                             [--xml=[^][ ]*], [])])dnl
   # Don't combine these Bison invocations since we want to be sure that
   # --report=all isn't required to get the full XML file.
-  AT_CHECK([[bison --report=all --report-file=xml-tests/test.output \
+  AT_BISON_CHECK_([[--report=all --report-file=xml-tests/test.output \
              --graph=xml-tests/test.dot ]]AT_BISON_ARGS,
            [[0]], [ignore], [ignore])
-  AT_CHECK([[bison --xml=xml-tests/test.xml ]]AT_BISON_ARGS,
+  AT_BISON_CHECK_([[--xml=xml-tests/test.xml ]]AT_BISON_ARGS,
            [[0]], [ignore], [ignore])
   m4_popdef([AT_BISON_ARGS])dnl
   [cp xml-tests/test.output expout]
@@ -541,6 +559,8 @@ m4_define([AT_BISON_CHECK_XML],
 m4_define([AT_QUELL_VALGRIND],
 [[[VALGRIND_OPTS="$VALGRIND_OPTS --leak-check=summary --show-reachable=no"; export VALGRIND_OPTS;]]])
 
+
+
 ## ------------------------ ##
 ## Compiling C, C++ Files.  ##
 ## ------------------------ ##
@@ -554,13 +574,16 @@ m4_define([AT_QUELL_VALGRIND],
 # otherwise pass "-c"; this is a hack.  The default SOURCES is OUTPUT
 # with trailing .o removed, and ".c" appended.
 m4_define([AT_COMPILE],
-[AT_CHECK(m4_join([ ],
+[AT_CHECK([case $POSIXLY_CORRECT_IS_EXPORTED:$C_COMPILER_POSIXLY_CORRECT in
+  true:false) echo 'cannot compile properly with POSIXLY_CORRECT' && exit 77;;
+esac])
+AT_CHECK(m4_join([ ],
                   [$CC $CFLAGS $CPPFLAGS],
                   [m4_bmatch([$1], [[.]], [-c], [$LDFLAGS])],
                   [-o $1],
                   [m4_default([$2], [m4_bpatsubst([$1], [\.o$]).c])],
                   [m4_bmatch([$1], [[.]], [], [$LIBS])]),
-          0, [ignore], [ignore])])
+           0, [ignore], [ignore])])
 
 # AT_COMPILE_CXX(OUTPUT, [SOURCES = OUTPUT.cc])
 # ---------------------------------------------
@@ -579,7 +602,7 @@ AT_CHECK(m4_join([ ],
                  [-o $1],
                  [m4_default([$2], [m4_bpatsubst([$1], [\.o$]).cc])],
                  [m4_bmatch([$1], [[.]], [], [$LIBS])]),
-        0, [ignore], [ignore])])
+         0, [ignore], [ignore])])
 
 # AT_JAVA_COMPILE(SOURCES)
 # ------------------------
@@ -587,7 +610,8 @@ AT_CHECK(m4_join([ ],
 # is not installed.
 m4_define([AT_JAVA_COMPILE],
 [AT_KEYWORDS(java)
-AT_SKIP_IF([[test -z "$CONF_JAVA$CONF_JAVAC"]])
+AT_SKIP_IF([[test -z "$CONF_JAVAC"]])
+AT_SKIP_IF([[test -z "$CONF_JAVA"]])
 AT_CHECK([[$SHELL ../../../javacomp.sh ]$1],
          [[0]], [ignore], [ignore])])
 
@@ -618,27 +642,65 @@ m4_define([AT_FULL_COMPILE],
 [java],
   [AT_BISON_CHECK([-o $1.java $1.y])
    AT_LANG_COMPILE([$1],
-                   m4_join([ ],
-                           [$1.java],
-                           m4_ifval($2, [[$1-$2.java]]),
+                    m4_join([ ],
+                            [$1.java],
+                            m4_ifval($2, [[$1-$2.java]]),
                            m4_ifval($3, [[$1-$3.java]])))],
 [c++],
   [AT_BISON_CHECK([-o $1.cc $1.y])
    AT_LANG_COMPILE([$1],
-                   m4_join([ ],
-                           [$1.cc],
-                           m4_ifval($2, [[$1-$2.cc]]),
+                     m4_join([ ],
+                             [$1.cc],
+                             m4_ifval($2, [[$1-$2.cc]]),
                            m4_ifval($3, [[$1-$3.cc]])))],
 [c],
   [AT_BISON_CHECK([-o $1.c $1.y])
    AT_LANG_COMPILE([$1],
-                   m4_join([ ],
-                           [$1.c],
-                           m4_ifval($2, [[$1-$2.c]]),
+                  m4_join([ ],
+                          [$1.c],
+                          m4_ifval($2, [[$1-$2.c]]),
                            m4_ifval($3, [[$1-$3.c]])))])
 ])
 
 
+
+# AT_SKIP_IF_CANNOT_LINK_C_AND_CXX
+# --------------------------------
+# Check that we can link together C and C++ objects.
+m4_define([AT_SKIP_IF_CANNOT_LINK_C_AND_CXX],
+[AT_DATA([c-and-cxx.h],
+[[#ifdef __cplusplus
+extern "C"
+{
+#endif
+  int fortytwo (void);
+#ifdef __cplusplus
+}
+#endif
+]])
+AT_DATA([c-only.c],
+[[#include "c-and-cxx.h"
+int
+main (void)
+{
+  return fortytwo () == 42 ? 0 : 1;
+}
+]])
+AT_DATA([cxx-only.cc],
+[[#include "c-and-cxx.h"
+int fortytwo ()
+{
+  return 42;
+}
+]])
+AT_COMPILE([c-only.o], [c-only.c])
+AT_COMPILE_CXX([cxx-only.o], [cxx-only.cc])
+AT_CHECK([$CXX $CXXFLAGS $CPPFLAGS $LDFLAGS c-only.o cxx-only.o -o c-and-cxx ||
+          exit 77], [ignore], [ignore])
+AT_PARSER_CHECK([./c-and-cxx])
+])
+
+
 ## ---------------------------- ##
 ## Running a generated parser.  ##
 ## ---------------------------- ##