Compiling on Ubuntu 10.04 LTS AMD64 on a GoGrid virtual machine from 2012-01-12 checkout.
Bison upgraded to v2.5, and downgraded to v2.4.1 Make process for both versions resulted in the following errors: make[3]: Leaving directory `/usr/local/src/pgbuild/src/backend/catalog' make -C parser gram.h make[3]: Entering directory `/usr/local/src/pgbuild/src/backend/parser' /usr/local/bin/bison -d -o gram.c gram.y gram.y: conflicts: 370 reduce/reduce gram.y: expected 0 reduce/reduce conflicts gram.y:10482.27-10494.33: warning: rule useless in parser due to conflicts: func_expr: COLLATION FOR '(' a_expr ')' make[3]: *** [gram.c] Error 1 make[3]: Leaving directory `/usr/local/src/pgbuild/src/backend/parser' make[2]: *** [parser/gram.h] Error 2 make[2]: Leaving directory `/usr/local/src/pgbuild/src/backend' make[1]: *** [all-backend-recurse] Error 2 make[1]: Leaving directory `/usr/local/src/pgbuild/src' make: *** [all-src-recurse] Error 2