Hi Sam,
On Sat, May 25, 2019 at 2:40 AM Sam Ravnborg <sam@xxxxxxxxxxxx> wrote:
>
> Hi Jani
>
> > Sometimes it's useful to be able to explicitly ensure certain headers
> > remain self-contained, i.e. that they are compilable as standalone
> > units, by including and/or forward declaring everything they depend on.
> >
> > Add special target header-test-y where individual Makefiles can add
> > headers to be tested if CONFIG_HEADER_TEST is enabled. This will
> > generate a dummy C file per header that gets built as part of extra-y.
>
> Very useful, thanks.
> I have cooked up something ad-hoc a couple of times but having it as a
> standard feature in the build system is much better.
> The we can let some of our infrastructure pick up an issues
> automatically.
>
> >
> > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
> > Cc: Michal Marek <michal.lkml@xxxxxxxxxxx>
> > Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> > ---
> > Documentation/kbuild/makefiles.txt | 7 +++++++
> > init/Kconfig | 9 +++++++++
> > scripts/Makefile.build | 10 ++++++++++
> > scripts/Makefile.lib | 3 +++
> > 4 files changed, 29 insertions(+)
> >
> > diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
> > index 03c065855eaf..73df58e5ea0c 100644
> > --- a/Documentation/kbuild/makefiles.txt
> > +++ b/Documentation/kbuild/makefiles.txt
> > @@ -1036,6 +1036,13 @@ When kbuild executes, the following steps are followed (roughly):
> > In this example, extra-y is used to list object files that
> > shall be built, but shall not be linked as part of built-in.a.
> >
> > + header-test-y
> > +
> > + header-test-y specifies headers (*.h) in the current directory that
> > + should be compile tested to ensure they are self-contained,
> > + i.e. compilable as standalone units. If CONFIG_HEADER_TEST is enabled,
> > + this autogenerates dummy sources to include the headers, and builds them
> > + as part of extra-y.
> Do we want to restrict this to current directory only?
> Sometimes we could use this for headers in include/ but let it
> trigger for the relevant subsystem.
> So for example drivers/gpu/drm/Makefile will include the rules
> for all headers in include/drm/*
>
> The alternative would be Makefiles (of Kbuild files)
> scattered in the directories with headers and then some
> infrastructure to visit those.
>
> Follow patch extend the header-test feature to work with
> headers in include/
Following the obj-y pattern,
I want to make header-test-y relative to $(obj).
> Example:
> # Header files from this directory
> header-test-y += drm_crtc_helper_internal.h
> header-test-y += drm_crtc_internal.h
These are described in drivers/gpu/drm/Makefile.
> ..
> .
> # Header files from include/drm
> header-test-y += drm/amd_asic_type.h
> header-test-y += drm/ati_pcigart.h
These are described in $(srctree)/include/Makefile.
> ...
>
>
> In the patch $* is used to get the "stem" from the pattern.
> This is the filname of the header file without extension.
>
>
> Sam
>
>
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 4d4bf698467a..ca132ab3a551 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -295,11 +295,10 @@ $(obj)/%.lst: $(src)/%.c FORCE
> # ---------------------------------------------------------------------------
>
> quiet_cmd_header_test = HDRTEST $@
> - cmd_header_test = echo "\#include \"$(<F)\"" > $@
> + cmd_header_test = echo "\#include <$(2).h>" > $@
>
> -# FIXME: would be nice to be able to limit this implicit rule to header-test-y
> -$(obj)/%.header_test.c: $(src)/%.h FORCE
> - $(call if_changed,header_test)
> +$(obj)/%.header_test.c:
> + $(call cmd,header_test,$*)
>
> # Compile assembler sources (.S)
> # ---------------------------------------------------------------------------
>
Agree, this is much better,
and it is what scripts/Makefile.asm-generic does.
But, you do not need to pass '$*' via the argument.
I prefer this:
quiet_cmd_header_test = HDRTEST $@
cmd_header_test = echo "\#include \"$*.h\"" > $@
$(obj)/%.header_test.c:
$(call cmd,header_test)
--
Best Regards
Masahiro Yamada
