From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [PATCH v4 1/5] mk: introduce helper to check valid
	compiler argument
Date: Mon, 14 Jan 2019 12:35:28 +0100
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References: <20190106131933.7898-1-jerinj@marvell.com>
 <20190109103915.29210-1-pbhagavatula@marvell.com>
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Cc: dev@dpdk.org, "Gavin.Hu@arm.com" <Gavin.Hu@arm.com>,
 "bruce.richardson@intel.com" <bruce.richardson@intel.com>
To: Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>,
 Jerin Jacob Kollanukkaran <jerinj@marvell.com>
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09/01/2019 11:39, Pavan Nikhilesh Bhagavatula:
> From: Jerin Jacob <jerinj@marvell.com>
> 
> Introduce rte_cc_has_argument() Makefile helper to
> check a given argument is support by the compiler.
> 
> Example Usage:
> 
> include $(RTE_SDK)/mk/rte.helper.mk
> MACHINE_CFLAGS += $(call rte_cc_has_argument, -mcpu=octeontx2)
> 
> This would allow adding -mcpu=octeontx2 in MACHINE_CFLAGS
> if it is only supported by the compiler. The use case for such
> scheme is to enable the mcpu optimization if the compiler
> supports else it needs to compile the source code without
> any errors.
> 
> This patch also moves inclusion of toolchain's rte.vars.mk
> to before the machine's rte.vars.mk inclusion to make
> correct CC available for the cross compile case.
> 
> Signed-off-by: Jerin Jacob <jerinj@marvell.com>
> Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
> ---
> --- /dev/null
> +++ b/mk/rte.helper.mk
> @@ -0,0 +1,12 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright(c) 2018 Marvell International Ltd
> +
> +# rte_cc_has_argument
> +# Usage: MACHINE_CFLAGS += $(call rte_cc_has_argument, -mno-avx512f)
> +# Return the argument if the argument is supported by the compiler.
> +#
> +define rte_cc_has_argument
> +	$(shell $(CC) -Werror $(1) -c -x c /dev/null -o tmp$$ 2> /dev/null && rm -f tmp$$ && echo $(1) | xargs echo -n)
> +endef

What is tmp$$ ?

If the command is interrupted in the middle, temp file is not cleaned.
We could fix it with "trap".
Is it possible to just avoid creating a temporary file?