While I was trying to install PostgreSQL from the git repository to start contributing I faced this issue. When I try to type ./configure it gives me this error
checking for a thread-safe mkdir -p... /usr/bin/mkdir -p
checking for bison... /c/GnuWin32/bin/bison
configure: using bison (GNU Bison) 2.4.1
checking for flex... configure: error:
*** The installed version of Flex, /c/GnuWin32/bin/flex, is too old to use with PostgreSQL.
*** Flex version 2.5.35 or later is required, but this is C:\GnuWin32\bin\flex.exe version 2.5.4.
Look at the last two lines, the error says that the installed version of flex is too old and is 2.4 which is correct and not too old and should be valid but actually I can't proceed beyond this point. And I double checked the version of flex
$ flex --version
C:\GnuWin32\bin\flex.exe version 2.5.4
and made sure that it is properly included in PATH
$ which flex
/c/GnuWin32/bin/flex
