Re: [XEN PATCH v2.1 1/4] build,include: rework shell script for headers++.chk

[Jan Beulich <jbeulich@xxxxxxxx>]

On 21.06.2022 12:11, Anthony PERARD wrote:
> The command line generated for headers++.chk by make is quite long,
> and in some environment it is too long. This issue have been seen in
> Yocto build environment.
> 
> Error messages:
>     make[9]: execvp: /bin/sh: Argument list too long
>     make[9]: *** [include/Makefile:181: include/headers++.chk] Error 127
> 
> Rework so that we do the foreach loop in shell rather that make to
> reduce the command line size by a lot. We also need a way to get
> headers prerequisite for some public headers so we use a switch "case"
> in shell to be able to do some simple pattern matching. Variables
> alone in POSIX shell don't allow to work with associative array or
> variables with "/".
> 
> Also rework headers99.chk as it has a similar implementation, even if
> with only two headers to check the command line isn't too long at the
> moment.
> 
> Reported-by: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>
> Fixes: 28e13c7f43 ("build: xen/include: use if_changed")
> Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>

I have committed this, but strictly speaking imo the R-b should have
been dropped because ...

> ---
> 
> Notes:
>     v3:
>     - add one more pattern to avoid a possible empty body for "case"
>     - use $() instead of `` to execute get_prereq()
>     - also convert headers99_chk
>     - convert some 'tab' to 'space', have only 1 tab at start of line

... at least the added headers99_chk conversion was not a purely
mechanical change.

Jan

>     v2:
>     - fix typo in commit message
>     - fix out-of-tree build
>     
>     v1:
>     - was sent as a reply to v1 of the series
> 
>  xen/include/Makefile | 37 +++++++++++++++++++++++++++++--------
>  1 file changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/xen/include/Makefile b/xen/include/Makefile
> index 617599df7e..510f65c92a 100644
> --- a/xen/include/Makefile
> +++ b/xen/include/Makefile
> @@ -141,13 +141,24 @@ cmd_header_chk = \
>  quiet_cmd_headers99_chk = CHK     $@
>  define cmd_headers99_chk
>       rm -f $@.new; \
> -     $(foreach i, $(filter %.h,$^),                                        \
> -         echo "#include "\"$(i)\"                                          \
> +     get_prereq() {                                                        \
> +         case $$1 in                                                       \
> +         $(foreach i, $(filter %.h,$^),                                    \
> +         $(if $($(patsubst $(srctree)/%,%,$(i))-prereq),                   \
> +             $(i)$(close)                                                  \
> +             echo "$(foreach j, $($(patsubst $(srctree)/%,%,$(i))-prereq), \
> +                     -include $(j).h)";;))                                 \
> +         *) ;;                                                             \
> +         esac;                                                             \
> +     };                                                                    \
> +     for i in $(filter %.h,$^); do                                         \
> +         echo "#include "\"$$i\"                                           \
>           | $(CC) -x c -std=c99 -Wall -Werror                               \
>             -include stdint.h                                               \
> -           $(foreach j, $($(patsubst $(srctree)/%,%,$i)-prereq), -include 
> $(j).h) \
> +           $$(get_prereq $$i)                                              \
>             -S -o /dev/null -                                               \
> -         || exit $$?; echo $(i) >> $@.new;) \
> +         || exit $$?; echo $$i >> $@.new;                                  \
> +     done;                                                                 \
>       mv $@.new $@
>  endef
>  
> @@ -158,13 +169,23 @@ define cmd_headerscxx_chk
>           touch $@.new;                                                     \
>           exit 0;                                                           \
>       fi;                                                                   \
> -     $(foreach i, $(filter %.h,$^),                                        \
> -         echo "#include "\"$(i)\"                                          \
> +     get_prereq() {                                                        \
> +         case $$1 in                                                       \
> +         $(foreach i, $(filter %.h,$^),                                    \
> +         $(if $($(patsubst $(srctree)/%,%,$(i))-prereq),                   \
> +             $(i)$(close)                                                  \
> +             echo "$(foreach j, $($(patsubst $(srctree)/%,%,$(i))-prereq), \
> +                     -include c$(j))";;))                                  \
> +         *) ;;                                                             \
> +         esac;                                                             \
> +     };                                                                    \
> +     for i in $(filter %.h,$^); do                                         \
> +         echo "#include "\"$$i\"                                           \
>           | $(CXX) -x c++ -std=gnu++98 -Wall -Werror -D__XEN_TOOLS__        \
>             -include stdint.h -include $(srcdir)/public/xen.h               \
> -           $(foreach j, $($(patsubst $(srctree)/%,%,$i)-prereq), -include 
> c$(j)) \
> +           $$(get_prereq $$i)                                              \
>             -S -o /dev/null -                                               \
> -         || exit $$?; echo $(i) >> $@.new;) \
> +         || exit $$?; echo $$i >> $@.new; done;                            \
>       mv $@.new $@
>  endef
>