Build unsupported

[BenBE]

This allows to run configure in a way such that the current platform is treated as an unsupported one.

This is mainly intended to allow for testing consistency of the code inside the unsupported platform directory.

[Explorer09]

I think you did it wrong. You should use the variablemy_htop_platform. host_os is an Autoconf-reserved variable that might imply a cross-compiler should be used.

[Explorer09]

Just a personal idea: I don't like adding a configure option for something that is meant for developers (porting to new platforms).
I think an easier method is to allow an undocumented override of my_htop_platform, and then a builder can run configure like this:

export my_htop_platform=unsupported; ./configure --enable-werror --enable-unicode

[BenBE]

Currently there's no easy way to influence my_htop_platform without duplicating much of the platform selection logic. And I'd actually also be fine if compiling for the unsupported platform was treated/handled as a cross-build.

I think, if we want to keep host_os untouched, we could initialize htop_host_os as host_os and do the override on htop_host_os.

I'm open to alternate suggestions. The goal for this PR is mostly to get the code for the unsupported platform into the usual CI builds, and using an explicit configure switch seemed like the most straight forward solution to me.

[Explorer09]

@BenBE The problem with --enable-build-as-unsupported is that it conflicts with --enable-pcp as both options would override my_htop_platform.

[BenBE]

I also noticed, that ./configure --host=none seems to work equally well …

[Explorer09]

@BenBE That's perhaps unintentional. You should specify --host=x86_64-unknown-unsupported_os instead. That's the "target triplet" format.

[BenBE]

Nope, that's intentional and correct, as config.sub translates single-part information into the full triplet.

Cf. config.sub for the full implementation …

FWIW:

$ ./configure --host=x86_64-unknown-unsupported_os
checking build system type... x86_64-pc-linux-gnu
checking host system type... Invalid configuration `x86_64-unknown-unsupported_os': OS `unsupported_os' not recognized
configure: error: /bin/bash ./build-aux/config.sub x86_64-unknown-unsupported_os failed

A full, arch-independent version could be:

$ ./configure --host=$(uname -m)-unknown-none

[Explorer09]

After a bit of thinking, I now believe your approach ./configure --host=$(uname -m)-none might be the cleanest one. As long as there is no cross-compiler named $(uname -m)-none-gcc, configure would be happy to grab the native compiler to do what we've intended.