[Buildroot] [PATCH v4 2/2] support/dependencies: set cmake version min to 3.10

[Yann E. MORIN <yann.morin.1998@free.fr>]

James, All,

On 2019-10-12 09:26 -0600, James Hilliard spake thusly:
> We retain 3.8 as the minimum for hosts without a c++ toolchain.
> 
> All packages that require 3.10 or newer themselves require a c++ toolchain.
> 
> This is required by wpewebkit and webkitgtk.
> 
> Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
> Reviewed-by: Adrian Perez de Castro <aperez@igalia.com>
> 
> ---
> Changes v3 -> v4:
>   - retain support for version 3.8.2 for older toolchains
> ---
>  support/dependencies/check-host-cmake.mk | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/support/dependencies/check-host-cmake.mk b/support/dependencies/check-host-cmake.mk
> index 5604713de6..7d59708573 100644
> --- a/support/dependencies/check-host-cmake.mk
> +++ b/support/dependencies/check-host-cmake.mk
> @@ -1,9 +1,17 @@
> -# Set this to either 3.8 or higher, depending on the highest minimum
> +# Set this to either 3.10 or higher, depending on the highest minimum
>  # version required by any of the packages bundled in Buildroot. If a
>  # package is bumped or a new one added, and it requires a higher
>  # version, our cmake infra will catch it and build its own.
> +# Newer versions of cmake require a c++11 toolchain so we should
> +# only build newer versions if our host gcc supports c++11.
> +# Packages that depend upon newer cmake versions all currently
> +# require a c++11 toolchain themselves.
>  #
> +ifeq ($(BR2_HOST_GCC_AT_LEAST_4_8),y)
> +BR2_CMAKE_VERSION_MIN = 3.10
> +else
>  BR2_CMAKE_VERSION_MIN = 3.8
> +endif

Sorry, but this is still not good for me.

BR2_CMAKE_VERSION_MIN is really meant to be the highest minimal cmake
version the cmake-packages in Buildroot need.

Semantically (and I really mean _semantically_) it feels really wrong to
correlate the minimum cmake version with the host-gcc version.

With your patch, a target cmake-package that needs cmake-3.10, will also
have to know that it should also need a host-gcc >= 4.8, even thou it is
a pure target package.

Furthermore, the discussion is happening in this patch, but it really
applies to both, because if the host-provided cmake is too old, then
we're going to build host-cmake-3.15 now, which as Arnout noted on IRC,
is full of even more C++11-isms (but do all of those require gcc-4.8?)

o, I am decidely not happy with this... :-(

However, maybe we can look at how we solved a similar issue for glibc.
glibc requires make-4.0+, but Buildroot only requires 3.81+, and we
build glibc by passing a specific version of make. Maybe we could do
something similar for webkit...

We still require cmake-3.8 at minimum, but for webkit-stuff, we depend
on host-cmake-3.10_or_above_whatever, and explicitly use that cmake for
webkit, by introducing a new variable in the infra, like we have
FOO_MAKE, we could introduce FOO_CMAKE (if not already present).

Thoughts?

Regards,
Yann E. MORIN.

>  BR2_CMAKE_CANDIDATES ?= cmake cmake3
>  BR2_CMAKE ?= $(call suitable-host-package,cmake,\
> -- 
> 2.20.1
> 
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> buildroot at busybox.net
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