Re: [dpdk-dev] [PATCH v2 5/7] build: MinGW-w64 support for Meson

[Bruce Richardson <bruce.richardson@intel.com>]

On Thu, Feb 06, 2020 at 09:44:24AM +0300, Dmitry Kozlyuk wrote:
> MinGW-w64 linker does not mimic MS linker options, so the build system
> must differentiate between linkers on Windows. Use GNU linker options
> with GCC and MS linker options with Clang.
> 
> MinGW-w64 by default uses MSVCRT stdio, which does not comply to ANSI,
> most notably its formatting and string handling functions. MinGW-w64
> support for the Universal CRT (UCRT) is ongoing, but the toolchain
> provides its own standard-complying implementation of stdio. The latter
> is used in the patch to support formatting in DPDK.
> 
> Signed-off-by: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>
> ---
>  config/meson.build         | 14 ++++++++++++++
>  lib/librte_eal/meson.build |  3 +++
>  lib/meson.build            |  8 ++++++--
>  3 files changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/config/meson.build b/config/meson.build
> index 28a57f56f..9b955f9ef 100644
> --- a/config/meson.build
> +++ b/config/meson.build
> @@ -14,6 +14,10 @@ foreach env:supported_exec_envs
>  	set_variable('is_' + env, exec_env == env)
>  endforeach
>  
> +# MS linker requires special treatment.
> +# FIXME: use cc.get_linker_id() with Meson >= 0.54
> +is_ms_linker = is_windows and (cc.get_id() == 'clang')
> +
>  # set the major version, which might be used by drivers and libraries
>  # depending on the configuration options
>  pver = meson.project_version().split('.')
> @@ -241,6 +245,16 @@ if is_freebsd
>  	add_project_arguments('-D__BSD_VISIBLE', language: 'c')
>  endif
>  
> +if is_windows
> +	# Minimum supported API is Windows 7.
> +	add_project_arguments('-D_WIN32_WINNT=0x0601', language: 'c')
> +
> +	# Use MinGW-w64 stdio, because DPDK assumes ANSI-compliant formatting.
> +	if cc.get_id() == 'gcc'
> +		add_project_arguments('-D__USE_MINGW_ANSI_STDIO', language: 'c')
> +	endif
> +endif
> +
>  if get_option('b_lto')
>  	if cc.has_argument('-ffat-lto-objects')
>  		add_project_arguments('-ffat-lto-objects', language: 'c')
> diff --git a/lib/librte_eal/meson.build b/lib/librte_eal/meson.build
> index 4be5118ce..eae8c2ba8 100644
> --- a/lib/librte_eal/meson.build
> +++ b/lib/librte_eal/meson.build
> @@ -20,6 +20,9 @@ endif
>  if cc.has_function('getentropy', prefix : '#include <unistd.h>')
>  	cflags += '-DRTE_LIBEAL_USE_GETENTROPY'
>  endif
> +if cc.get_id() == 'gcc'
> +	cflags += '-D__USE_MINGW_ANSI_STDIO'
> +endif

Is this snippet still needed, given you add this as a project arg above?