[PATCH v6 09/10] kbuild: add cmd_and_savecmd macro

[Masahiro Yamada <masahiroy@kernel.org>]

Separate out the command execution part of if_changed, as we did
for if_changed_dep.

This allows us to reuse it in if_changed_rule.

  define rule_foo
          $(call cmd_and_savecmd,foo)
          $(call cmd,bar)
  endef

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
---

(no changes since v4)

Changes in v4:
  - New.
    Resent of my previous submission.
    https://lore.kernel.org/all/20210831074004.3195284-10-masahiroy@kernel.org/

 scripts/Kbuild.include | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 455a0a6ce12d..ece44b735061 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -142,9 +142,11 @@ 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),                                        \
+if_changed = $(if $(if-changed-cond),$(cmd_and_savecmd),@:)
+
+cmd_and_savecmd =                                                            \
 	$(cmd);                                                              \
-	printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:)
+	printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd
 
 # Execute the command and also postprocess generated .d dependencies file.
 if_changed_dep = $(if $(if-changed-cond),$(cmd_and_fixdep),@:)
-- 
2.32.0