Re: [PATCH] kbuild, LLVMLinux: Add -Werror to cc-option to support clang

From: Michal Marek
Date: Wed Sep 24 2014 - 08:07:22 EST

On 2014-09-23 21:28, behanw@xxxxxxxxxxxxxxxxxx wrote:
> From: Mark Charlebois <charlebm@xxxxxxxxx>
> Clang will warn about unknown warnings but will not return false

You mean unknown options, right?

> unless -Werror is set. GCC will return false if an unknown
> warning is passed.
> Adding -Werror make both compiler behave the same.

Can you please limit it to the clang case? Add an internal variable that
either contains -Werror or nothing, depending on the compiler. What I
fear is that if we use -Werror unconditionally and the user (or some
automated build system) decides to add some silly option to KCFLAGS, we
will get silent failures in the cc-option tests. Of course, the same can
happen with clang, but there seems to be no way around it.

BTW, is there a chance that this would be fixed in some later clang
version? Accepting unknown commandline options is a rather unusual
behavior. How are all the ./configure scripts going to cope with it?

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