Re: [v3] kbuild: Port silent mode detection to future gnu make.

[Nicolas Schier <nicolas@fjasle.eu>]

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On Mon, Dec 05, 2022 at 04:48:19PM -0500 Dmitry Goncharov wrote:
> Port silent mode detection to the future (post make-4.4) versions of gnu make.
> 
> Makefile contains the following piece of make code to detect if option -s is
> specified on the command line.
> 
> ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
> 
> 
> This code is executed by make at parse time and assumes that MAKEFLAGS
> does not contain command line variable definitions.
> Currently if the user defines a=s on the command line, then at build only
> time MAKEFLAGS contains " -- a=s".
> However, starting with commit dc2d963989b96161472b2cd38cef5d1f4851ea34
> MAKEFLAGS contains command line definitions at both parse time and
> build time.
> 
> This '-s' detection code then confuses a command line variable
> definition which contains letter 's' with option -s.
> 
> $ # old make
> $ make net/wireless/ocb.o a=s
>   CALL    scripts/checksyscalls.sh
>   DESCEND objtool
> $ # this a new make which defines makeflags at parse time
> $ ~/src/gmake/make/l64/make net/wireless/ocb.o a=s
> $
> 
> We can see here that the letter 's' from 'a=s' was confused with -s.
> 
> This patch checks for presence of -s using a method recommended by the
> make manual here
> https://www.gnu.org/software/make/manual/make.html#Testing-Flags.
> 
> 
> Signed-off-by: Dmitry Goncharov <dgoncharov@users.sf.net>
> Reported-by: Jan Palus <jpalus+gnu@fastmail.com>
> Link: https://lists.gnu.org/archive/html/bug-make/2022-11/msg00190.html
> 
> diff --git a/Makefile b/Makefile
> index 6f846b1f2618..fbd9ff4a61e7 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -93,10 +93,17 @@ endif
> 
>  # If the user is running make -s (silent mode), suppress echoing of
>  # commands
> +# make-4.0 (and later) keep single letter options in the 1st word of MAKEFLAGS.
> 
> -ifneq ($(findstring s,$(filter-out --%,$(MAKEFLAGS))),)
> -  quiet=silent_
> -  KBUILD_VERBOSE = 0
> +ifeq ($(filter 3.%,$(MAKE_VERSION)),)
> +silence:=$(findstring s,$(firstword -$(MAKEFLAGS)))
> +else
> +silence:=$(findstring s,$(filter-out --%,$(MAKEFLAGS)))
> +endif
> +
> +ifeq ($(silence),s)
> +quiet=silent_
> +KBUILD_VERBOSE = 0

Thanks for that patch.  Following its development was quite interesting!

Are there some (possibly unwritten) style recommendations for Linux
Makefiles/Kbuilds, e.g. regarding spaces around assignment operators and after
commas?

Personally, I would have liked to see those spaces here as I think it would be
better for style consistency.

Kind regards,
Nicolas


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