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
