kbuild: add %.lex.c and %.tab.[ch] to 'targets' automatically

Linux commit b23d1a241f4eb44ae55785c9b65274717c8e2c1e
(adjust commit log for barebox)

This will be needed for Barebox to switch to the compile-time
generation of lexers and parsers.

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.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 11 insertions, 0 deletions

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 883435bdf6..3c686e46ff 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -379,6 +379,17 @@ $(call multi_depend, $(multi-used-m), .o, -objs -y)
 targets += $(multi-used-y) $(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
 # ---------------------------------------------------------------------------