X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/a4e4295ad2c737bb64fc0b1fcb164a15e6b1f281..465df9c65c7022a66e9cea7145b80886174e90af:/m4/flex.m4?ds=sidebyside

diff --git a/m4/flex.m4 b/m4/flex.m4
index 7e1b914e..5ab431a2 100644
--- a/m4/flex.m4
+++ b/m4/flex.m4
@@ -1,4 +1,4 @@
-# flex.m4 serial 1
+# flex.m4 serial 2
 # Copyright (C) 2012 Free Software Foundation, Inc.
 # This file is free software; the Free Software Foundation
 # gives unlimited permission to copy and/or distribute it,
@@ -20,10 +20,27 @@ fi])
 
 # _AC_PROG_LEX_YYTEXT_DECL
 # ------------------------
-# Check for the Lex output root, the Lex library, and whether Lex
-# declares yytext as a char * by default.
+# Check whether this is Flex, for the Lex output root, the Lex library,
+# and whether Lex declares yytext as a char * by default.
 m4_define([_AC_PROG_LEX_YYTEXT_DECL],
+[AC_CACHE_CHECK([whether lex is flex],
+                [ac_cv_prog_lex_is_flex],
 [cat >conftest.l <<_ACEOF[
+%option debug nodefault noinput nounput noyywrap never-interactive
+%x SC_CONF_TEST
+%%
+a { BEGIN SC_CONF_TEST; }
+]_ACEOF
+if _AC_DO_VAR([LEX conftest.l]); then
+  ac_cv_prog_lex_is_flex=yes
+else
+  ac_cv_prog_lex_is_flex=no
+fi
+])
+AC_SUBST([LEX_IS_FLEX],
+         [`test "$ac_cv_prog_lex_is_flex" = yes && echo true || echo false`])dnl
+
+cat >conftest.l <<_ACEOF[
 %%
 a { ECHO; }
 b { REJECT; }
@@ -61,7 +78,7 @@ if test -z "${LEXLIB+set}"; then
     for ac_lib in '' -lfl -ll; do
       LIBS="$ac_lib $ac_save_LIBS"
       AC_LINK_IFELSE([AC_LANG_DEFINES_PROVIDED[`cat $LEX_OUTPUT_ROOT.c`]],
-	[ac_cv_lib_lex=$ac_lib])
+        [ac_cv_lib_lex=$ac_lib])
       test "$ac_cv_lib_lex" != 'none needed' && break
     done
     LIBS=$ac_save_LIBS
@@ -87,8 +104,8 @@ LIBS=$ac_save_LIBS
 dnl
 if test $ac_cv_prog_lex_yytext_pointer = yes; then
   AC_DEFINE([YYTEXT_POINTER], [1],
-	    [Define to 1 if `lex' declares `yytext' as a `char *' by default,
-	     not a `char[]'.])
+            [Define to 1 if `lex' declares `yytext' as a `char *' by default,
+             not a `char[]'.])
 fi
 rm -f conftest.l $LEX_OUTPUT_ROOT.c
 ])# _AC_PROG_LEX_YYTEXT_DECL