X-Git-Url: https://git.draconx.ca/gitweb/dxcommon.git/blobdiff_plain/c576e02220d3ebf04a11b8568d4f96c4aab8fb84..a525f18001c5d6339d125548c403df0bcd044f2b:/m4/bison.m4

diff --git a/m4/bison.m4 b/m4/bison.m4
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+dnl Copyright © 2021 Nick Bowler
+dnl License WTFPL2: Do What The Fuck You Want To Public License, version 2.
+dnl This is free software, you are free to do what the fuck you want to.
+dnl There is NO WARRANTY, to the extent permitted by law.
+
+dnl DX_PROG_BISON([min-version], [action-if-found], [action-if-not-found])
+dnl
+dnl Search PATH for a reasonably modern GNU Bison of at least the given
+dnl minimum version, which may be empty to accept any version.  Here,
+dnl "reasonably modern" means it supports the %code construct and (if
+dnl a version is specified), the %require construct.
+dnl
+dnl If found, the BISON variable (which is substituted by AC_SUBST) is
+dnl set with the result, and action-if-found is executed.  Otherwise,
+dnl action-if-not-found is executed if nonempty, else configure will
+dnl exit with a fatal error.
+AC_DEFUN([DX_PROG_BISON],
+[AC_ARG_VAR([BISON], [GNU Bison command])dnl
+AC_ARG_VAR([BISONFLAGS], [Additional options to pass to Bison])dnl
+cat >conftest.y <<'EOF'
+m4_ifnblank([$1], [%require "$1"
+])%code top {
+/* SUPPORTS_CODE_TOP_WITNESS */
+}
+%code requires {
+/* SUPPORTS_CODE_REQUIRES_WITNESS */
+}
+%{
+int yylex(void) { return 0; }
+void yyerror(const char *msg) { }
+%}
+%%
+input:
+%%
+int main(void) { return yyparse(); }
+EOF
+AC_CACHE_CHECK([for bison], [ac_cv_path_BISON],
+[dx_cv_bison_found=:
+AC_PATH_PROGS_FEATURE_CHECK([BISON], [bison],
+[_DX_BISON_DO_TEST([$ac_path_BISON],
+[bison_relcmd=${ac_path_BISON##*/}
+bison_bypath=`command -v "$bison_relcmd"` #''
+ac_cv_path_BISON=$ac_path_BISON
+test x"$bison_bypath" = x"$ac_path_BISON" && ac_cv_path_BISON=$bison_relcmd
+ac_path_BISON_found=:
+dx_cv_bison_works=yes])], [ac_cv_path_BISON=no dx_cv_bison_found=false])])
+AS_IF([$dx_cv_bison_found],
+[BISON=$ac_cv_path_BISON
+AC_CACHE_CHECK([whether $BISON works and is m4_ifnblank([$1],
+    [at least version $1], [reasonably modern])],
+  [dx_cv_bison_works],
+  [_DX_BISON_DO_TEST([$BISON], [dx_cv_bison_works=yes], [dx_cv_bison_works=no])])])
+AS_IF([test x"$dx_cv_bison_works" = x"yes"],
+  [$2], [m4_default([$3], [AC_MSG_FAILURE(
+[GNU bison m4_ifnblank([$1], [version at least $1 ])is required.
+
+The latest version may be found at <https://www.gnu.org/software/bison/>.
+])])])
+rm -f conftest.tab.[[ch]] conftest.y y.tab.[[ch]]
+])
+
+AC_DEFUN([_DX_BISON_DO_TEST], [rm -f conftest.tab.[[ch]] y.tab.[[ch]]
+AS_IF([DX_RUN_LOG([$1 --file-prefix=conftest --defines conftest.y])],
+  [AC_LINK_IFELSE([AC_LANG_SOURCE([[#include "conftest.tab.c"]])],
+    [AS_IF([DX_RUN_LOG([grep SUPPORTS_CODE_TOP_WITNESS conftest.tab.c]) &&
+            DX_RUN_LOG([grep SUPPORTS_CODE_REQUIRES_WITNESS conftest.tab.h])],
+      [$2], [$3])], [$3])], [$3])])