headers: move CPP guards into YY_*_INCLUDED to avoid collisions

[bison.git] / data / c.m4

diff --git a/data/c.m4 b/data/c.m4
index 3954613bfb7c5e992678356315c110c156fcaf2a..fd2203ebbe595688859f109704fd3425f565c6ca 100644 (file)
--- a/data/c.m4
+++ b/data/c.m4
@@ -17,6 +17,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+m4_include(b4_pkgdatadir/[c-like.m4])
 
 # b4_tocpp(STRING)
 # ----------------
@@ -29,19 +30,21 @@ m4_define([b4_tocpp],
 # ------------------
 # A valid C macro name to use as a CPP header guard for FILE.
 m4_define([b4_cpp_guard],
-[b4_tocpp(m4_defn([b4_prefix])/[$1])])
+[[YY_]b4_tocpp(m4_defn([b4_prefix])/[$1])[_INCLUDED]])
 
 
 # b4_cpp_guard_open(FILE)
 # b4_cpp_guard_close(FILE)
 # ------------------------
-# Open/close CPP inclusion guards for FILE.
+# If FILE does not expand to nothing, open/close CPP inclusion guards for FILE.
 m4_define([b4_cpp_guard_open],
+[m4_ifval(m4_quote($1),
 [#ifndef b4_cpp_guard([$1])
-# define b4_cpp_guard([$1])])
+# define b4_cpp_guard([$1])])])
 
 m4_define([b4_cpp_guard_close],
-[#endif b4_comment([!b4_cpp_guard([$1])])])
+[m4_ifval(m4_quote($1),
+[#endif b4_comment([!b4_cpp_guard([$1])])])])
 
 
 ## ---------------- ##
@@ -417,17 +420,6 @@ m4_define([b4_case],
 $2
     break;])
 
-# b4_dollar_dollar_(NAME, FIELD, DEFAULT-FIELD)
-# ---------------------------------------------
-# If FIELD (or DEFAULT-FIELD) is non-null, read it in pointer NAME,
-# otherwise just dereference.
-m4_define([b4_dollar_dollar_],
-[m4_if([$2], [[]],
-       [m4_ifval([$3], [($1->$3)],
-                 [(*$1)])],
-       [($1->$2)])])
-
-
 # b4_symbol_actions(FILENAME, LINENO,
 #                   SYMBOL-TAG, SYMBOL-NUM,
 #                   SYMBOL-ACTION, SYMBOL-TYPENAME)
@@ -437,16 +429,13 @@ m4_define([b4_dollar_dollar_],
 # Define b4_dollar_dollar([TYPE-NAME]), and b4_at_dollar, which are
 # invoked where $<TYPE-NAME>$ and @$ were specified by the user.
 m4_define([b4_symbol_actions],
-[m4_pushdef([b4_dollar_dollar],
-   [b4_dollar_dollar_([yyvaluep], m4_dquote($][1), [$6])])dnl
-m4_pushdef([b4_at_dollar], [(*yylocationp)])dnl
+[b4_dollar_pushdef([(*yyvaluep)], [$6], [(*yylocationp)])dnl
       case $4: /* $3 */
 b4_syncline([$2], [$1])
        $5;
 b4_syncline([@oline@], [@ofile@])
        break;
-m4_popdef([b4_at_dollar])dnl
-m4_popdef([b4_dollar_dollar])dnl
+b4_dollar_popdef[]dnl
 ])