support/dependencies: clarify intended use of host bison/flex
We should not rely on host installed bison/flex for target code. This
ensures better reproducibility of generated code.
http://lists.busybox.net/pipermail/buildroot/2020-November/296786.html
Cc: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
diff --git a/support/dependencies/check-host-bison-flex.mk b/support/dependencies/check-host-bison-flex.mk
index 233b6c5..14a232f 100644
--- a/support/dependencies/check-host-bison-flex.mk
+++ b/support/dependencies/check-host-bison-flex.mk
@@ -1,5 +1,9 @@
# If the system lacks bison or flex, add
# dependencies to suitable host packages
+#
+# BR2_{BISON,FLES}_HOST_DEPENDENCY should only be used to build code
+# that runs on host, e.g. Kconfig. To build code for target use plain
+# host-{bison,flex}.
ifeq ($(shell which bison 2>/dev/null),)
BR2_BISON_HOST_DEPENDENCY = host-bison
