On Fri, May 17, 2019 at 4:48 AM Jani Nikula <jani.nikula@xxxxxxxxx> wrote: > > 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. > > 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. > > --- 6.7 Commands useful for building a boot image > > diff --git a/init/Kconfig b/init/Kconfig > index 4592bf7997c0..d91b157201b1 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -95,6 +95,15 @@ config COMPILE_TEST > here. If you are a user/distributor, say N here to exclude useless > drivers to be distributed. > > +config HEADER_TEST > + bool "Compile test headers that should be standalone compilable" > + help > + Compile test headers listed in header-test-y target to ensure they are > + self-contained, i.e. compilable as standalone units. > + > + If you are a developer or tester and want to ensure the requested > + headers are self-contained, say Y here. Otherwise, choose N. > + > config LOCALVERSION > string "Local version - append to kernel release" > help > diff --git a/scripts/Makefile.build b/scripts/Makefile.build > index 76ca30cc4791..4d4bf698467a 100644 > --- a/scripts/Makefile.build > +++ b/scripts/Makefile.build > @@ -291,6 +291,16 @@ quiet_cmd_cc_lst_c = MKLST $@ > $(obj)/%.lst: $(src)/%.c FORCE > $(call if_changed_dep,cc_lst_c) > > +# Dummy C sources for header test (header-test-y target) > +# --------------------------------------------------------------------------- > + > +quiet_cmd_header_test = HDRTEST $@ > + cmd_header_test = echo "\#include \"$(<F)\"" > $@ > + > +# FIXME: would be nice to be able to limit this implicit rule to header-test-y > +$(obj)/%.header_test.c: $(src)/%.h FORCE > + $(call if_changed,header_test) > + > # Compile assembler sources (.S) > # --------------------------------------------------------------------------- > > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib > index 8a1f64f17740..c2839de06485 100644 > --- a/scripts/Makefile.lib > +++ b/scripts/Makefile.lib > @@ -66,6 +66,9 @@ extra-y += $(patsubst %.dtb,%.dt.yaml, $(dtb-y)) > extra-$(CONFIG_OF_ALL_DTBS) += $(patsubst %.dtb,%.dt.yaml, $(dtb-)) > endif > > +# Test self-contained headers > +extra-$(CONFIG_HEADER_TEST) += $(patsubst %.h,%.header_test.o,$(header-test-y)) > + > # Add subdir path > > extra-y := $(addprefix $(obj)/,$(extra-y)) > -- > 2.20.1 > Thanks, probably we should do this. At least, this check will be useful for uapi headers since the kernel does not test the self-containedness of exported headers, (then turned out be problematic later in user-space). I will take a little time to considier how far we can extend the idea about "headers should be self-contained". Thank you. -- Best Regards Masahiro Yamada
