[Buildroot] [PATCH v2 1/5] package/gdb: rework dependency for C++11

[Yann E. MORIN]

Thomas, All,

On 2018-02-05 22:10 +0100, Thomas Petazzoni spake thusly:
> As we are about to switch to 8.0 as the default gdb dependency, we
> need to adjust how the gdb dependencies are handled. Indeed, from 8.0
> onwards, gdb needs a C++11 capable compiler, i.e at least gcc 4.8.
> 
> Until now, Config.in.host was making sure that gdb 8.0 was not
> selectable if the cross-compilation toolchain did not have C++ support
> with gcc >= 4.8. This worked fine because the default version of gdb,
> used as the target gdb version when no host gdb is built, was 7.11,
> and did not require C++11.
> 
> With the switch to 8.0 as the default version, when target gdb is
> enabled but not host gdb, 8.0 is used, which means we need a C++11
> capable compiler. The dependencies in Config.in.host are no longer
> sufficient.
> 
> So instead, we remove the target-related dependencies from
> Config.in.host and move them properly to Config.in. The overall logic
> is the following:
> 
>  - In Config.in.host, BR2_PACKAGE_HOST_GDB_ARCH_SUPPORTS ensures that
>    we have at least host gcc 4.8 if we're on ARC, because the ARC gdb
>    needs C++11. We remove the target toolchain related dependencies
>    from here.
> 
>  - In Config.in.host, the version selection ensures that 8.0 cannot be
>    selected if the host toolchain does not have at least gcc 4.8. We
>    remove the target toolchain related dependencies from here.
> 
>  - In Config.in, we handle gdb more like a regular target package,
>    with a Config.in comment when its dependencies are not met. A
>    hidden boolean BR2_PACKAGE_GDB_NEEDS_CXX11 indicates when the
>    currently selected version requires C++11. Based on that, we show
>    the Config.in comment, and add the proper dependencies to
>    BR2_PACKAGE_GDB. It is worth mentioning that
>    BR2_PACKAGE_GDB_NEEDS_CXX11 is intentionally created to be !7.10 &&
>    !7.11 && !7.12 instead of 8.0, because we will gradually add more
>    C++11-requiring versions, and remove non-C++11-requiring versions.

Nice refactoring. :-)

Yet, a comment below...

> Signed-off-by: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
> ---
>  package/gdb/Config.in      | 15 +++++++++++++++
>  package/gdb/Config.in.host |  3 ---
>  2 files changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/package/gdb/Config.in b/package/gdb/Config.in
> index af020f40c5..b7f0565b92 100644
> --- a/package/gdb/Config.in
> +++ b/package/gdb/Config.in
> @@ -11,15 +11,30 @@ comment "gdb/gdbserver needs a toolchain w/ threads, threads debug"
>  	depends on BR2_PACKAGE_GDB_ARCH_SUPPORTS
>  	depends on !BR2_TOOLCHAIN_HAS_THREADS || !BR2_TOOLCHAIN_HAS_THREADS_DEBUG
>  
> +config BR2_PACKAGE_GDB_NEEDS_CXX11
> +	bool
> +	default y
> +	depends on !BR2_GDB_VERSION_7_10
> +	depends on !BR2_GDB_VERSION_7_11
> +	depends on !BR2_GDB_VERSION_7_12

I would have expected that the various versions would select this,
i.e. something like:

    config BR2_PACKAGE_GDB_NEEDS_CXX11
        bool


    config BR2_GDB_VERSION_7_10
        bool "7.10"

    config BR2_GDB_VERSION_8_0
        bool "8.0"
        select BR2_PACKAGE_GDB_NEEDS_CXX11

Otherwise, I'm OK with the patch.

Reviewed-by: "Yann E. MORIN" <yann.morin.1998 at free.fr>

Regards,
Yann E. MORIN.

> +comment "gdb/gdbserver >= 8.x needs a toolchain w/ C++, gcc >= 4.8"
> +	depends on BR2_PACKAGE_GDB_NEEDS_CXX11
> +	depends on !BR2_INSTALL_LIBSTDCPP || !BR2_TOOLCHAIN_GCC_AT_LEAST_4_8
> +
>  config BR2_PACKAGE_GDB
>  	bool "gdb"
>  	depends on BR2_TOOLCHAIN_HAS_THREADS && BR2_TOOLCHAIN_HAS_THREADS_DEBUG
>  	depends on BR2_PACKAGE_GDB_ARCH_SUPPORTS
> +	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_8 || !BR2_PACKAGE_GDB_NEEDS_CXX11
> +	depends on BR2_INSTALL_LIBSTDCPP || !BR2_PACKAGE_GDB_NEEDS_CXX11
>  	# When the external toolchain gdbserver is copied to the
>  	# target, we don't allow building a separate gdbserver. The
>  	# one from the external toolchain should be used.
>  	select BR2_PACKAGE_GDB_SERVER if \
>  		(!BR2_PACKAGE_GDB_DEBUGGER && !BR2_TOOLCHAIN_EXTERNAL_GDB_SERVER_COPY)
> +	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_8 || !BR2_PACKAGE_GDB_NEEDS_CXX11
> +	depends on BR2_INSTALL_LIBSTDCPP || !BR2_PACKAGE_GDB_NEEDS_CXX11
>  	help
>  	  GDB, the GNU Project debugger, allows you to see what is
>  	  going on `inside' another program while it executes -- or
> diff --git a/package/gdb/Config.in.host b/package/gdb/Config.in.host
> index 99e1cae5ba..8676c6f01b 100644
> --- a/package/gdb/Config.in.host
> +++ b/package/gdb/Config.in.host
> @@ -3,7 +3,6 @@ config BR2_PACKAGE_HOST_GDB_ARCH_SUPPORTS
>  	default y
>  	# The ARC version needs C++11, thus gcc >= 4.8, like gdb-8.0.x
>  	depends on BR2_HOST_GCC_AT_LEAST_4_8 || !BR2_arc
> -	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_8 || !BR2_arc
>  	depends on !((BR2_arm || BR2_armeb) && BR2_BINFMT_FLAT)
>  	depends on !BR2_microblaze
>  	depends on !BR2_nios2
> @@ -63,9 +62,7 @@ config BR2_GDB_VERSION_7_12
>  config BR2_GDB_VERSION_8_0
>  	bool "gdb 8.0.x"
>  	# Needs a C++11 compiler
> -	depends on BR2_INSTALL_LIBSTDCPP
>  	depends on BR2_HOST_GCC_AT_LEAST_4_8
> -	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_4_8
>  
>  endchoice
>  
> -- 
> 2.14.3
> 

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