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Re: AC_PROG_CC: how to distinguish clang from gcc?

From: David A. Wheeler
Subject: Re: AC_PROG_CC: how to distinguish clang from gcc?
Date: Fri, 5 Feb 2021 11:40:47 -0500

> On Feb 5, 2021, at 9:51 AM, Todd C. Miller <> wrote:
> On Fri, 05 Feb 2021 15:42:28 +0100, =?utf-8?Q?S=C3=A9bastien?= Hinderer wrote:
>> It seems AC_PROG_CC wrongly believes clang is gcc and that may cause problems
>> when clang is passed a warning which is only supposrted by gcc, as is
>> the case e.g. for -Wno-stringop-truncation.
> clang also defines __GNUC__ and the related defines, which is why
> it is identified as gcc.
>> Is there a recommended way to determine for sure from a configure script
>> whether the detected C compiler is clang or gcc?

I would *discourage* trying to figure out if a C compiler is gcc or clang.
Instead, create separate detectors for whatever you’re looking for.

The gcc & clang groups coordinate with each other; they try to provide the same
flags & API for the same functionality, and occasionally copy from each other.
So trying to detect “do this if GCC” is generally wrong; clang may have that 
interface & functionality
when someone compiles the code.

--- David A. Wheeler

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