why this compilation error

[lilzz]

Code: Select all

y.tab.c:557:1: error: duplicate ‘extern’
 //extern YYSTYPE yylval;
 ^
make[1]: *** [pat_decl_y.lo] Error 1
make[1]: Leaving directory `/home/lilzz/alliance-5.0/ppt/src'
make: *** [all-recursive] Error 1
lilzz@lilzz-Latitude-E6400:~/alliance-5.0/ppt$ 

//extern YYSTYPE yylval I already have that // which is a comment.
why still throwing me an error

[AndyD]

It is only a comment in C99 and beyond. Possibly the compiler flags are setting it to C89.

I used to love YACC. I haven't used YACC in a long time ...

How do I enable C++ styled comments in gcc while leaving ANSI enabled?

[jojopi]

As always, we need a lot more context about what you have done.

For a start, what is wrong with yum or apt-get install alliance ?