[Buildroot] [PATCH 1/2] package/linux-backports: use buildroot host flex and bison

[Julien Olivain]

Upstream backports package does not define the LEX/YACC Makefile
variables, contrary to the Kernel which is defining those in [1]. The
default "lex" and "yacc" are then used. On some systems, "yacc" is
Berkeley Yacc. Kconfig parser files are using non-Posix Bison
constructs.

Attempting to generate the parser with byacc fails with error:

    yacc: e - line 97 of "zconf.y", syntax error
    %destructor {
    ^

This patch adds the missing dependencies on host-flex and host-bison,
and make sure the package compilation will use those, to fix this issue.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=73a4f6dbe70a1b93c11e2d1d6ca68f3522daf434

Signed-off-by: Julien Olivain <ju.o at free.fr>
---
 package/linux-backports/linux-backports.mk | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/package/linux-backports/linux-backports.mk b/package/linux-backports/linux-backports.mk
index 1d7d6e7f00..fafb8efb91 100644
--- a/package/linux-backports/linux-backports.mk
+++ b/package/linux-backports/linux-backports.mk
@@ -11,6 +11,8 @@ LINUX_BACKPORTS_SITE = $(BR2_KERNEL_MIRROR)/linux/kernel/projects/backports/stab
 LINUX_BACKPORTS_LICENSE = GPL-2.0
 LINUX_BACKPORTS_LICENSE_FILES = COPYING
 
+LINUX_BACKPORTS_DEPENDENCIES = host-bison host-flex
+
 ifeq ($(BR2_PACKAGE_LINUX_BACKPORTS_USE_DEFCONFIG),y)
 LINUX_BACKPORTS_KCONFIG_FILE = $(LINUX_BACKPORTS_DIR)/defconfigs/$(call qstrip,$(BR2_PACKAGE_LINUX_BACKPORTS_DEFCONFIG))
 else ifeq ($(BR2_PACKAGE_LINUX_BACKPORTS_USE_CUSTOM_CONFIG),y)
@@ -33,6 +35,8 @@ LINUX_BACKPORTS_KCONFIG_OPTS = $(LINUX_BACKPORTS_MAKE_OPTS)
 # LINUX_BACKPORTS_MODULE_MAKE_OPTS is used by the kernel-module infra.
 #
 LINUX_BACKPORTS_MAKE_OPTS = \
+	LEX="$(HOST_DIR)/bin/flex" \
+	YACC="$(HOST_DIR)/bin/bison" \
 	BACKPORT_DIR=$(@D) \
 	KLIB_BUILD=$(LINUX_DIR) \
 	KLIB=$(TARGET_DIR)/lib/modules/$(LINUX_VERSION_PROBED) \
-- 
2.28.0