For PR738:
Demote check for bison from error to warning and make sure that the
makefile can handle an empty definition for BISON variable.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@29861 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/autoconf/m4/bison.m4 b/autoconf/m4/bison.m4
index e186af0..48b83cc 100644
--- a/autoconf/m4/bison.m4
+++ b/autoconf/m4/bison.m4
@@ -8,7 +8,8 @@
AC_DEFUN([AC_PROG_BISON],
[AC_CACHE_CHECK([],[llvm_cv_has_bison],[AC_PROG_YACC()])
if test "$YACC" != "bison -y"; then
- AC_MSG_ERROR([bison not found but required])
+ AC_SUBST(BISON,[])
+ AC_MSG_WARN([bison not found, can't rebuild grammars])
else
- AC_SUBST(BISON,[bison],[location of bison])
+ AC_SUBST(BISON,[bison])
fi])