linux/scripts/genksyms/Makefile
Masahiro Yamada b23d1a241f kbuild: add %.lex.c and %.tab.[ch] to 'targets' automatically
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' in the
Kconfig Makefile because zconf.lex.c is included from zconf.tab.c
instead of being compiled separately.  It should be deleted after
Kconfig is more refactored.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Frank Rowand <frowand.list@gmail.com>
2018-04-07 19:04:02 +09:00

39 lines
1.1 KiB
Makefile

# SPDX-License-Identifier: GPL-2.0
hostprogs-y := genksyms
always := $(hostprogs-y)
genksyms-objs := genksyms.o parse.tab.o lex.lex.o
# FIXME: fix the ambiguous grammar in parse.y and delete this hack
#
# Suppress shift/reduce, reduce/reduce conflicts warnings
# unless W=1 is specified.
#
# Just in case, run "$(YACC) --version" without suppressing stderr
# so that 'bison: not found' will be displayed if it is missing.
ifeq ($(findstring 1,$(KBUILD_ENABLE_EXTRA_GCC_CHECKS)),)
quiet_cmd_bison_no_warn = $(quet_cmd_bison)
cmd_bison_no_warn = $(YACC) --version >/dev/null; \
$(cmd_bison) 2>/dev/null
$(obj)/parse.tab.c: $(src)/parse.y FORCE
$(call if_changed,bison_no_warn)
quiet_cmd_bison_h_no_warn = $(quet_cmd_bison_h)
cmd_bison_h_no_warn = $(YACC) --version >/dev/null; \
$(cmd_bison_h) 2>/dev/null
$(obj)/parse.tab.h: $(src)/parse.y FORCE
$(call if_changed,bison_h_no_warn)
endif
# -I needed for generated C source (shipped source)
HOSTCFLAGS_parse.tab.o := -I$(src)
HOSTCFLAGS_lex.lex.o := -I$(src)
# dependencies on generated files need to be listed explicitly
$(obj)/lex.lex.o: $(obj)/parse.tab.h