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authorMasahiro Yamada <masahiroy@kernel.org>2021-08-13 15:30:05 +0900
committerMasahiro Yamada <masahiroy@kernel.org>2021-09-03 08:17:19 +0900
commite1f86d7b4b2a5213b012c2b4fe3e5b6ad537686e (patch)
tree8d727e69ee73d264c626599c794718d47b228599 /scripts
parent6796e80409b9031458e33dc39a3ac8aa3b93855b (diff)
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: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Nicolas Schier <n.schier@avm.de>
Diffstat (limited to 'scripts')
-rw-r--r--scripts/Kbuild.include7
1 files changed, 6 insertions, 1 deletions
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index c3c975a92318..cdec22088423 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -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), \