From 63bda378a7eacfb02501ce2f1d996427f29b1336 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@fb.com>
Date: Tue, 29 Dec 2015 12:23:17 -0700
Subject: [PATCH] configure: check if lex requires/fails with -o for output

Signed-off-by: Jens Axboe <axboe@fb.com>
---
 Makefile  |  4 ++++
 configure | 13 +++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/Makefile b/Makefile
index 510e2570..1b5c9a6f 100644
--- a/Makefile
+++ b/Makefile
@@ -297,7 +297,11 @@ override CFLAGS += -DFIO_VERSION='"$(FIO_VERSION)"'
 
 ifdef CONFIG_ARITHMETIC
 lex.yy.c: exp/expression-parser.l
+ifdef CONFIG_LEX_USE_O
 	$(QUIET_LEX)$(LEX) -o $@ $<
+else
+	$(QUIET_LEX)$(LEX) $<
+endif
 
 lex.yy.o: lex.yy.c y.tab.h
 	$(QUIET_CC)$(CC) -o $@ $(CFLAGS) $(CPPFLAGS) -c $<
diff --git a/configure b/configure
index af26165e..a0d5a15f 100755
--- a/configure
+++ b/configure
@@ -1494,6 +1494,16 @@ fi
 fi
 fi
 
+# Check if lex fails using -o
+if test "$arith" = "yes" ; then
+$LEX -o lex.yy.c exp/expression-parser.l 2> /dev/null
+if test "$?" = "0" ; then
+  lex_use_o="yes"
+else
+  lex_use_o="no"
+fi
+fi
+
 echo "lex/yacc for arithmetic       $arith"
 
 ##########################################
@@ -1756,6 +1766,9 @@ if test "$arith" = "yes" ; then
   else
     echo "YACC=$YACC" >> $config_host_mak
   fi
+  if test "$lex_use_o" = "yes" ; then
+    echo "CONFIG_LEX_USE_O=y" >> $config_host_mak
+  fi
 fi
 if test "$getmntent" = "yes" ; then
   output_sym "CONFIG_GETMNTENT"
-- 
2.25.1