configure is written in sh, not in C, so you need

diff --git a/configure.ac b/configure.ac
index 5b86e90925..c91b7de322 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3436,7 +3436,7 @@ AC_DEFUN
     AC_DEFINE(USE_TOOLKIT_SCROLL_BARS)
     USE_TOOLKIT_SCROLL_BARS=yes
   fi
-elif test "${window_system}" != "x11" && "${window_system}" != "none"; then
+elif test "${window_system}" != "x11" && test "${window_system}" !=
"none"; then
   AC_MSG_ERROR(Non-toolkit scroll bars are not implemented for your system)
 fi


yes, adding "test" here, correctly produces an error.

On Wed, Jun 15, 2022 at 7:20 PM Robert Pluim <rpluim@gmail.com> wrote:

> >>>>> On Wed, 15 Jun 2022 08:59:20 +0800, Po Lu <luangruo@yahoo.com> said:
>
>     Po> Eli Zaretskii <eliz@gnu.org> writes:
>     >> Thanks for testing, I will let it to Po Lu to decide whether that's
>     >> the proper fix in this case.
>
>     Po> Non-toolkit scroll bars use different kinds of events compared to
>     Po> toolkit scroll bars.  PGTK only implements the latter kind, so
> turning
>     Po> toolkit scroll bars off should trigger this piece of configure.ac:
>
>     Po>   elif test "${window_system}" != "x11" && "${window_system}" !=
> "none"; then
>     Po>     AC_MSG_ERROR(Non-toolkit scroll bars are not implemented for
> your system)
>     Po>   fi
>
>     Po> Perhaps Sameer's configure script is out of date and needs to be
>     Po> regenerated.
>
> configure is written in sh, not in C, so you need
>
> diff --git a/configure.ac b/configure.ac
> index 5b86e90925..c91b7de322 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -3436,7 +3436,7 @@ AC_DEFUN
>      AC_DEFINE(USE_TOOLKIT_SCROLL_BARS)
>      USE_TOOLKIT_SCROLL_BARS=yes
>    fi
> -elif test "${window_system}" != "x11" && "${window_system}" != "none";
> then
> +elif test "${window_system}" != "x11" && test "${window_system}" !=
> "none"; then
>    AC_MSG_ERROR(Non-toolkit scroll bars are not implemented for your
> system)
>  fi
>
>
> (or use -a to avoid repeating the 'test')
>
> Robert
> --
>