[PATCH] kbuild: ensure Make >= 3.82 is used

[Masahiro Yamada <masahiroy@kernel.org>]

Documentation/process/changes.rst notes the minimal GNU Make version,
but it is not checked anywhere.

We could check $(MAKE_VERSION), but another simple way is to check
$(.FEATURES) since the feature list always grows although this way
is not always possible. For example Make 4.0 through 4.2 have the
same set of $(.FEATURES).

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

Changes in v3:
  - Check the version in a different way

 Makefile | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Makefile b/Makefile
index 2dda1e9a717a..66dfc5751470 100644
--- a/Makefile
+++ b/Makefile
@@ -11,6 +11,11 @@ NAME = Hurr durr I'ma ninja sloth
 # Comments in this file are targeted only to the developer, do not
 # expect to learn how to build the kernel reading this file.
 
+# Ensure Make >= 3.82
+ifeq ($(filter undefine,$(.FEATURES)),)
+$(error Make $(MAKE_VERSION) is too old)
+endif
+
 $(if $(filter __%, $(MAKECMDGOALS)), \
 	$(error targets prefixed with '__' are only for internal use))
 
-- 
2.34.1