[Flex-help] help needed in the transition from flex 2.59 to 2.6

[Rollastre P. <rol...@gm...>]

Hello list.

I looks like there are some changes in the code generated by flex 2.59 
and 2.6 (in C++) that break my build.

in 2.59 the code in question in the XXXX.lexer.cpp is this:

if(!yyin)

/*%if-c-only*/

/*%endif*/

/*%if-c++-only*/

yyin=&std::cin;

/*%endif*/

if(!yyout)

/*%if-c-only*/

/*%endif*/

/*%if-c++-only*/

yyout=&std::cout;

/*%endif*/


and in 2.6 is like this:
if(!yyin)

/*%if-c-only*/

/*%endif*/

/*%if-c++-only*/

yyin.rdbuf(std::cin.rdbuf());

/*%endif*/

if(!yyout)

/*%if-c-only*/

/*%endif*/

/*%if-c++-only*/

yyout.rdbuf(std::cout.rdbuf());

/*%endif*/



It turns out that the 2.59 version works fine but the 2.6 doesn't 
compile because yyin and yyout are pointers. I have searched for a 
solution for my problem in the list but I couldn't find anything. I also 
googled and found this

http://stackoverflow.com/questions/34438023/openfoam-flex-yyin-rdbufstdcin-rdbuf-error

http://htaccess9simo.blogspot.com.es/2015/12/openfoam-flex-yyinrdbufstdcinrdbuf-error.html

Which basically workaround the problem by downgrading to 2.59 in the 
/usr/bin. I already tested this and worked for me too. But I would 
expect there is a better solution which doesn't require that my build 
system ships a specific version of flex. Does somebody know what am I 
doing (or not doing) that causes this problem?

Thank you and sorry if the question is already posted, I just couldn't 
find it!