$ make
make all in app...
make[1]: Entering directory '/home/guest/Desktop/soon/NatLang-master/app'
bison -d src/NatLang.y
src/NatLang.y: warning: 77 shift/reduce conflicts [-Wconflicts-sr]
mv NatLang.tab.c src/NatLang.tab.cpp
mv NatLang.tab.h include/NatLang.tab.h
mkdir -p build
g++ -c -o build/NatLang.tab.o src/NatLang.tab.cpp -Wall -g -Iinclude -I../libxl/include -std=c++0x
flex src/NatLang.l
"src/NatLang.l", line 66: unrecognized %option: reentrant
Makefile:102: recipe for target 'src/lex.NatLang.cpp' failed
make[1]: *** [src/lex.NatLang.cpp] Error 1
make[1]: Leaving directory '/home/guest/Desktop/soon/NatLang-master/app'
Makefile:23: recipe for target 'all' failed
make: *** [all] Error 2
how fix?