Recent changes (master)

index 510e257..1b5c9a6 100644
@@ -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 $<

index af26165..e92e96b 100755
@@ -135,7 +135,7 @@ show_help="no"
 exit_val=0
 gfio_check="no"
 libhdfs="no"
-disable_lex="no"
+disable_lex=""
 prefix=/usr/local
 
 # parse options

@@ -171,6 +171,8 @@ for opt do
   ;;
   --disable-lex) disable_lex="yes"
   ;;
+  --enable-lex) disable_lex="no"
+  ;;
   --disable-shm) no_shm="yes"
   ;;
   --disable-optimizations) disable_opt="yes"

@@ -198,6 +200,7 @@ if test "$show_help" = "yes" ; then
   echo "--disable-gfapi        Disable gfapi"
   echo "--enable-libhdfs       Enable hdfs support"
   echo "--disable-lex          Disable use of lex/yacc for math"
+  echo "--enable-lex           Enable use of lex/yacc for math"
   echo "--disable-shm          Disable SHM support"
   echo "--disable-optimizations Don't enable compiler optimizations"
   exit $exit_val

@@ -240,6 +243,12 @@ fi
 # cross-compiling to one of these OSes then you'll need to specify
 # the correct CPU with the --cpu option.
 case $targetos in
+AIX)
+  # Unless explicitly enabled, turn off lex.
+  if test -z "$disable_lex" ; then
+    disable_lex="yes"
+  fi
+  ;;
 Darwin)
   # on Leopard most of the system is 32-bit, so we have to ask the kernel if
   # we can run 64-bit userspace code.

@@ -1455,7 +1464,7 @@ yacc="no"
 yacc_is_bison="no"
 lex="no"
 arith="no"
-if test "$disable_lex" = "no"; then
+if test "$disable_lex" = "no" || test -z "$disable_lex" ; then
 if test "$targetos" != "SunOS" ; then
 LEX=$(which lex 2> /dev/null)
 if test -x "$LEX" ; then

@@ -1494,6 +1503,16 @@ 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 +1775,9 @@ 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"