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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
To:     linux-kbuild@vger.kernel.org
Cc:     Sam Ravnborg <sam@ravnborg.org>,
        Michal Marek <michal.lkml@markovi.net>,
        linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Frank Rowand <frank.rowand@sony.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Masahiro Yamada <yamada.masahiro@socionext.com>
Subject: [PATCH 04/10] kbuild: add %.lex.c and %.tab.[ch] to 'targets' automatically
Date:   Fri, 23 Mar 2018 22:04:33 +0900
Message-Id: <1521810279-6282-4-git-send-email-yamada.masahiro@socionext.com>
In-Reply-To: <1521810279-6282-1-git-send-email-yamada.masahiro@socionext.com>
References: <1521810279-6282-1-git-send-email-yamada.masahiro@socionext.com>
Sender: linux-kernel-owner@vger.kernel.org
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Files generated by if_changed* must be added to 'targets' to include
*.cmd files.  Otherwise, they would be regenerated every time.

The build system automatically adds objects to 'targets' where
appropriate, such as obj-y, extra-y, etc. but does nothing for
intermediate files.  So, each Makefile needs to add them by itself.

There are some common cases where objects are generated by chained
rules.  Lexers and parsers are compiled like follows:

   %.lex.o <- %.lex.c <- %.l
   %.tab.o <- %.tab.c <- %.y

They are common patterns, so it is reasonable to take care of them
in the core Makefile instead of requiring each Makefile to do so.

At this moment, you cannot delete 'target += zconf.lex.c' because
zconf.lex.c is included from zconf.tab.c instead of being compiled.
This will be possible with further refactoring in the future.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 scripts/Makefile.build    | 11 +++++++++++
 scripts/dtc/Makefile      |  3 ---
 scripts/genksyms/Makefile |  2 --
 scripts/kconfig/Makefile  |  2 +-
 4 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 77cce68..36f7990 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -538,6 +538,17 @@ $(call multi_depend, $(multi-used-m), .o, -objs -y -m)
 targets += $(multi-used-m)
 targets := $(filter-out $(PHONY), $(targets))
 
+# Add intermediate targets:
+# When building objects with specific suffix patterns, add intermediate
+# targets that the final targets are derived from.
+intermediate_targets = $(foreach sfx, $(2), \
+				$(patsubst %$(strip $(1)),%$(sfx), \
+					$(filter %$(strip $(1)), $(targets))))
+# %.lex.o <- %.lex.c <- %.l
+# %.tab.o <- %.tab.[ch] <- %.y
+targets += $(call intermediate_targets, .lex.o, .lex.c) \
+	   $(call intermediate_targets, .tab.o, .tab.c .tab.h)
+
 # Descending
 # ---------------------------------------------------------------------------
 
diff --git a/scripts/dtc/Makefile b/scripts/dtc/Makefile
index d17ba64..9cac65b 100644
--- a/scripts/dtc/Makefile
+++ b/scripts/dtc/Makefile
@@ -27,6 +27,3 @@ HOSTCFLAGS_dtc-parser.tab.o := $(HOSTCFLAGS_DTC)
 
 # dependencies on generated files need to be listed explicitly
 $(obj)/dtc-lexer.lex.o: $(obj)/dtc-parser.tab.h
-
-# generated files need to include *.cmd
-targets := dtc-lexer.lex.c dtc-parser.tab.c dtc-parser.tab.h
diff --git a/scripts/genksyms/Makefile b/scripts/genksyms/Makefile
index f4749e8..aeefd47 100644
--- a/scripts/genksyms/Makefile
+++ b/scripts/genksyms/Makefile
@@ -32,5 +32,3 @@ HOSTCFLAGS_lex.lex.o := -I$(src)
 
 # dependencies on generated files need to be listed explicitly
 $(obj)/lex.lex.o: $(obj)/parse.tab.h
-
-targets := lex.lex.c parse.tab.c parse.tab.h
diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
index 1dcd797..5def877 100644
--- a/scripts/kconfig/Makefile
+++ b/scripts/kconfig/Makefile
@@ -207,7 +207,7 @@ gconf-objs	:= gconf.o zconf.tab.o
 
 hostprogs-y := conf nconf mconf kxgettext qconf gconf
 
-targets		+= zconf.tab.c zconf.lex.c
+targets		+= zconf.lex.c
 clean-files	:= qconf.moc .tmp_qtcheck .tmp_gtkcheck
 clean-files	+= gconf.glade.h
 clean-files     += config.pot linux.pot
-- 
2.7.4