Why does my Mac (OS X 10.7.3) have an old version (2.3) of Gnu Bison?

Question

The version of GNU Bison on my mac is 2.3 but I know that Bison 2.5 was released long ago. The book Flex & Bison uses version 2.5.

Should I upgrade to 2.5 m

Answer 1

you can install a new version with homebrew:

$ brew install bison

...

This formula is keg-only, which means it was not symlinked into /usr/local.

Mac OS X already provides this software and installing another version in
parallel can cause all kinds of trouble.

Some formulae require a newer version of bison.

Generally there are no consequences of this for you. If you build your
own software and it requires this formula, you'll need to add to your
build variables:

    LDFLAGS:  -L/usr/local/opt/bison/lib

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