Commit e1f86d7b authored by Masahiro Yamada's avatar Masahiro Yamada
Browse files

kbuild: warn if FORCE is missing for if_changed(_dep,_rule) and filechk 



if_changed, if_changed_dep, and if_changed_rule must have FORCE as a
prerequisite so the command line change is detected.

Documentation/kbuild/makefiles.rst clearly explains it:

  Note: It is a typical mistake to forget the FORCE prerequisite.

However, not all people follow the document.

This mistake occurred again and again, so a compelling force is needed.

Show a warning if FORCE is missing in the prerequisite of if_changed
and friends. Same for filechk.

Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
Tested-by: default avatarNicolas Schier <n.schier@avm.de>
parent 6796e804

scripts/Kbuild.include

+6 −1
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ kecho := $($(quiet)kecho) 
# - If the content differ the new file is used

# - If they are equal no change, and no timestamp update

define filechk

	$(check-FORCE)

	$(Q)set -e;						\

	mkdir -p $(dir $@);					\

	trap "rm -f $(dot-target).tmp" EXIT;			\
@@ -130,7 +131,11 @@ make-cmd = $(call escsq,$(subst $(pound),$$(pound),$(subst $$,$$$$,$(cmd_$(1)))) 
# PHONY targets skipped in both cases.

newer-prereqs = $(filter-out $(PHONY),$?)



if-changed-cond = $(newer-prereqs)$(cmd-check)

# It is a typical mistake to forget the FORCE prerequisite. Check it here so

# no more breakage will slip in.

check-FORCE = $(if $(filter FORCE, $^),,$(warning FORCE prerequisite is missing))



if-changed-cond = $(newer-prereqs)$(cmd-check)$(check-FORCE)



# Execute command if command has changed or prerequisite(s) are updated.

if_changed = $(if $(if-changed-cond),                                        \