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Date: Mon, 4 Nov 2019 20:18:11 +0000
From: Sergei Trofimovich <slyfox@gentoo.org>
To: Mattias Nissler <mnissler@chromium.org>
Cc: gentoo-dev@lists.gentoo.org
Subject: [gentoo-dev] Re: [PATCH] Fix tc-cpp-is-true to work with clang
Message-ID: <20191104201811.5a629cdd@sf>
In-Reply-To: <20191104101120.230510-1-mnissler@chromium.org>
References: <20191104101120.230510-1-mnissler@chromium.org>
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On Mon,  4 Nov 2019 10:11:20 +0000
Mattias Nissler <mnissler@chromium.org> wrote:

> Clang's preprocessor likes to output a leading newline, which makes
> the comparison always fail. GCC generates additional output with certain
> flags (e.g. -ggdb3) as well. Hence, switch the test to trigger a
> preprocessor error when the condition is not true and examine the exit
> code.
> 
> Bug: https://bugs.gentoo.org/698912
> 
> Signed-off-by: Mattias Nissler <mnissler@chromium.org>
> ---
>  eclass/toolchain-funcs.eclass | 15 +++++++--------
>  1 file changed, 7 insertions(+), 8 deletions(-)

Looks good! I'll pull it in to ::gentoo in a few days.

Thank you!

> diff --git a/eclass/toolchain-funcs.eclass b/eclass/toolchain-funcs.eclass
> index e358d484417..1bc6cbbc108 100644
> --- a/eclass/toolchain-funcs.eclass
> +++ b/eclass/toolchain-funcs.eclass
> @@ -207,14 +207,13 @@ tc-cpp-is-true() {
>  	local CONDITION=${1}
>  	shift
>  
> -	local RESULT=$($(tc-getTARGET_CPP) "${@}" -P - <<-EOF 2>/dev/null
> -			#if ${CONDITION}
> -			true
> -			#endif
> -		EOF
> -	)
> -
> -	[[ ${RESULT} == true ]]
> +	$(tc-getTARGET_CPP) "${@}" -P - <<-EOF >/dev/null 2>&1
> +		#if ${CONDITION}
> +		true
> +		#else
> +		#error false
> +		#endif
> +	EOF
>  }
>  
>  # @FUNCTION: tc-detect-is-softfloat
> -- 
> 2.21.0
> 


-- 

  Sergei