Yacc and Lex inclusion confusion

Question

I am wondering how to correctly compile a program with a Makefile that has calls to yyparse in it?

This is what I do:

I have a Makefile that compiles all my regular files and they have no connections to y.tab.c or lex.yy.c (Am I supposed to have them?)

I do this on top of my code:

#include "y.tab.c"
#include "lex.yy.c"
#include "y.tab.h"

This is what happens when I try to make the program:

When I just type in "make", it gives me many warnings. Some of the examples are shown below.

In function yywrap': /src/parser.y:12: multiple definition ofyywrap' server.o :/src/parser.y:12: first defined here utils.o:

In function yyparse': /src/y.tab.c:1175: multiple definition ofyyparse' server.o:/src/y.tab.c:1175: first defined here utils.o

I get many different errors referring to different yy_*** files. I have compiled successfully with multiple calls to yyparse in the past, but this time seems to be different. It seems an awful lot like an inclusion problem somewhere but I can't tell what it is. All my header files have ifndef conditions, as well.

Thanks for your help!

It is aconventional to include the Lex and Yacc generated C code into a single file - but it could be done as long as it is done in just one file. You only include the headers in other files, and only if they actually need the information from the headers. — Jonathan Leffler

dmckee --- ex-moderator kitten dmckee --- ex-moderator kitten · Accepted Answer · 2010-03-21T05:58:11

You should be compiling y.tab.c and lex.yy.c, not including them. Only include the header files (.h) in your sources that need them.

Then you link the resulting object files to produce the executable.

project: project.o t.tab.o lex.yy.o foo.o bar.o

y.tab.o: t.tab.c y.tab.h

lex.yy.o: lex.yy.c

# Assuming that you have correct pattern rules setup 
# or that the implicit rules will do...

Moreover, you can use make to insure that those files are up-to-date relative there generating files:

y.tab.c y.tab.h: project.yacc
        $(YACC) $<

lex.yy.c: project.lex
        $(LEX) $<

or more sophisticated command lines as needed.

Yacc and Lex inclusion confusion

1 Answers