Re: [PATCH for-4.14] tools: check go compiler version if present

[Ian Jackson <ian.jackson@xxxxxxxxxx>]

Nick Rosbrook writes ("[PATCH for-4.14] tools: check go compiler version if 
present"):
> Currently, no minimum go compiler version is required by the configure
> scripts. However, the go bindings actually will not build with some
> older versions of go. Add a check for a minimum go version of 1.11.1 in
> accordance with tools/golang/xenlight/go.mod.

> diff --git a/tools/configure.ac b/tools/configure.ac
> index a9af0a21c6..9d126b7a14 100644
> --- a/tools/configure.ac
> +++ b/tools/configure.ac
> @@ -338,6 +338,13 @@ AS_IF([test "x$golang" = "xy"], [
>              AC_MSG_ERROR([Go tools enabled, but missing go compiler])
>          ])
>          golang="n"
> +    ], [
> +        AX_COMPARE_VERSION([$GOVERSION], [lt], [1.11.1], [
> +            AS_IF([test "x$enable_golang" = "xyes"], [
> +                AC_MSG_ERROR(["Your version of go: $GOVERSION is not 
> supported"])
> +            ])
> +            golang="n"
> +        ])
>      ])
>  ])

I don't understand this code.  Why are you checking $enable_golang in
your new code whereas the old code checks $golang ?  I actually read
the generated code trying to see where $golang is set and AFAICT it is
only ever set to n ?

This is all very weird.  Surely golang should be enabled by default
when the proper compiler is present, and disabled by default
otherwise.  I think this effect will be quite hard to achieve with
AX_ARG_DEFAULT_ENABLE.  Probably you should be using AC_ARG_ENABLE
and doing the defaulting yourself so that you can use a computed
default etc.

The docs are not clear but reading the code, AC_ARG_ENABLE sets the
variable enable_foo to "no" if --disable-foo is given, to "" if
--enable-foo is given, or to the value given to
--enable-foo=VALUE.

Ian.