Re: AC_PROG_CC: how to distinguish clnag from gcc?

[David A . Wheeler]

     On Feb 5, 2021, at 9:51 AM, Todd C. Miller <Todd.Miller@sudo.ws>
     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