LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Jani Nikula <jani.nikula@intel.com>
To: linux-kbuild@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org,
	jani.nikula@intel.com, Chris Wilson <chris@chris-wilson.co.uk>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Michal Marek <michal.lkml@markovi.net>
Subject: [RFC 1/3] kbuild: add support for ensuring headers are self-contained
Date: Thu, 16 May 2019 22:48:16 +0300	[thread overview]
Message-ID: <20190516194818.29230-1-jani.nikula@intel.com> (raw)

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@chris-wilson.co.uk>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---
 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


             reply	other threads:[~2019-05-16 19:48 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-16 19:48 Jani Nikula [this message]
2019-05-16 19:48 ` [RFC 2/3] drm/i915: ensure headers remain self-contained Jani Nikula
2019-05-16 19:48 ` [RFC 3/3] DO NOT MERGE: drm/i915: add failing header to header-test-y Jani Nikula
2019-05-17  8:35 ` [RFC 1/3] kbuild: add support for ensuring headers are self-contained Chris Wilson
2019-05-18  5:29   ` Masahiro Yamada
2019-05-18  5:16 ` Masahiro Yamada
2019-05-20  9:20   ` [Intel-gfx] " Jani Nikula
2019-06-03 17:16     ` Masahiro Yamada
2019-05-24 17:40 ` Sam Ravnborg
2019-06-03 17:05   ` Masahiro Yamada
2019-06-03 17:33     ` Sam Ravnborg
2019-06-04  0:20       ` Masahiro Yamada

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190516194818.29230-1-jani.nikula@intel.com \
    --to=jani.nikula@intel.com \
    --cc=chris@chris-wilson.co.uk \
    --cc=intel-gfx@lists.freedesktop.org \
    --cc=linux-kbuild@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=michal.lkml@markovi.net \
    --cc=yamada.masahiro@socionext.com \
    --subject='Re: [RFC 1/3] kbuild: add support for ensuring headers are self-contained' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).