[Buildroot] [PATCH] package/qt5/qt5tools: mark qdoc option as broken

Thu Feb 27 06:51:51 UTC 2020

Romain, All,

On 2020-02-27 00:22 +0100, Romain Naour spake thusly:
> When qdoc option was added by [1] for Qt 5.12, the host-clang
> dependecy was added as if host-clang would provide a host native
> compiler.
> 
> The host-clang package provide host libclang libraries needed by
> the cross-build process for target packages. The default target
> arch is set with the target architecture. It would require adding
> compiler flag to select the architecture to generate binaries
> (host or target).
> 
> We can consider adding native build suport by merging the
> patch [3]. But it was not merged in time for Buildroot
> 2020.02.
> 
> So in the current state, host-clang is added to qt5tools
> dependency without taking into account BR2_PACKAGE_LLVM_ARCH_SUPPORTS.

Then when don't we simply add that depednency instead of hiding it
behind BROKEN?

See below for a phrasing proposal...

> But even with host native support in llvm/clang host packages, the
> host-clang dependency itself increase a lot the build time.
> 
> On a laptop with a i7-8565U CPU @ 1.80GHz, host-llvm takes 1100 sec
> (18,3min) to build and host-clang takes 1200 sec (20min) to build.
> qt5tools takes 18sec to build.
> 
> Increasing the build time by 40min just for the sake of building qdoc
> is not great.

Yes, and so what? If people want to build qdoc because they want to
generate documentation for their Qt-based programs, and upstream Qt has
decided they need clang, there is not much we can do about that, can we?

The build time is no reason to hide away a feature, so there is no
reason to reference that in the commit log (it could be a post-commit
note, though).

> Instead we may consider adding a new check in support/dependencies/dependencies.sh
> for llvm/clang installed on the build machine.
> This llvm/clang would be used for building qdoc (or mabe other host package).
> 
> But we need to be careful for the case where host-llvm and host-clang
> package are already build.
> 
> Then, the qt5tools package would set LLVM_INSTALL_DIR in the
> additional environment variables to pass to make in the build step,
> to provide the patch to llvm/clang headers and libraries.
> 
> Something like:
> define QT5TOOLS_BUILD_CMDS
> 	$(TARGET_MAKE_ENV) LLVM_INSTALL_DIR="`/usr/bin/llvm-config --prefix`" \
> 		$(MAKE) -C $(@D) sub-src-qmake_all
> [...]

All those proposals do not belogn to the commit log, but to a
post-commit note, too.

> Since all possible solution are too late for 2020.02 release, disable

*solution_s_.

> BR2_PACKAGE_QT5TOOLS_QDOC_TOOL option.
> 
> Fixes:
> http://autobuild.buildroot.net/results/3c0/3c0f27e953fa41bd973003a4b42b768b1636c91a/build-end.log
> 
> [1] 57c1d3be4ecadd6802414a0943185c4ab6d82937
> [2] https://www.linuxembedded.fr/2018/07/llvmclang-integration-into-buildroot
> [3] http://patchwork.ozlabs.org/patch/1204740/
> 
> Signed-off-by: Romain Naour <romain.naour at smile.fr>
> Cc: Yann E. MORIN <yann.morin at orange.com>
> Cc: Julien Corjon <corjon.j at ecagroup.com>
> Cc: Peter Seiderer <ps.report at gmx.net>
> ---
>  package/qt5/qt5tools/Config.in | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/package/qt5/qt5tools/Config.in b/package/qt5/qt5tools/Config.in
> index 14178abc29..5ef85a88b3 100644
> --- a/package/qt5/qt5tools/Config.in
> +++ b/package/qt5/qt5tools/Config.in
> @@ -19,6 +19,9 @@ config BR2_PACKAGE_QT5TOOLS_LINGUIST_TOOLS
>  
>  config BR2_PACKAGE_QT5TOOLS_QDOC_TOOL
>  	bool "qdoc host tool"
> +	# Needs llvm-config and libclang installed on the build machine.

No, that's wrong: it does not need them to be "installed on the build
machine". It just needs them.

> +	# host-llvm and host-clang packages doesn't provide a host compiler.
> +	depends on BROKEN

Here's my counter-proposal:

    config BR2_PACKAGE_QT5TOOLS_QDOC_TOOL
        bool "qdoc host tool"
        # Needs llvm-config and libclang for the host, which is not
        # currently supported in Buildroot, unless the target is
        # already supported by llvm.
        depends on BR2_PACKAGE_LLVM_ARCH_SUPPORTS

And a comment about it:

    comment "qdoc not supported for current target"
        depends on !BR2_PACKAGE_LLVM_ARCH_SUPPORTS

Regards,
Yann E. MORIN.

>  	help
>  	  This option enables the qdoc host tool.
>  
> -- 
> 2.24.1
> 

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