[Buildroot] [PATCH] toolchain/toolchain-wrapper: explicitly set Build ID to none if BR2_REPRODUCIBLE

[Atharva Lele <itsatharva@gmail.com>]

Build ID is added to binaries at link time. Building in different output
directories causes some packages to have different Build IDs, thus resulting in
non-reproducibility.

Adding "-Wl,--build-id=none" fixes this issue by disabling setting of Build ID.

Diffoscope output for Build ID issue: https://gitlab.com/snippets/1886180/raw

After this patch, build is reproducible - i.e. diffoscope does not produce any
output.

Signed-off-by: Atharva Lele <itsatharva@gmail.com>
---
 toolchain/toolchain-wrapper.c  | 3 +++
 toolchain/toolchain-wrapper.mk | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/toolchain/toolchain-wrapper.c b/toolchain/toolchain-wrapper.c
index 7a4b9c4007..f7f2a9ec97 100644
--- a/toolchain/toolchain-wrapper.c
+++ b/toolchain/toolchain-wrapper.c
@@ -98,6 +98,9 @@ static char *predef_args[] = {
 #if defined(BR_MIPS_TARGET_BIG_ENDIAN) || defined(BR_ARC_TARGET_BIG_ENDIAN)
 	"-EB",
 #endif
+#ifdef BR2_REPRODUCIBLE
+    "-Wl,--build-id=none",
+#endif
 #ifdef BR_ADDITIONAL_CFLAGS
 	BR_ADDITIONAL_CFLAGS
 #endif
diff --git a/toolchain/toolchain-wrapper.mk b/toolchain/toolchain-wrapper.mk
index 970bde76a0..21fc08f3ee 100644
--- a/toolchain/toolchain-wrapper.mk
+++ b/toolchain/toolchain-wrapper.mk
@@ -59,6 +59,10 @@ else ifeq ($(BR2_RELRO_FULL),y)
 TOOLCHAIN_WRAPPER_ARGS += -DBR2_RELRO_FULL
 endif
 
+ifeq ($(BR2_REPRODUCIBLE),y)
+TOOLCHAIN_WRAPPER_ARGS += -DBR2_REPRODUCIBLE
+endif
+
 define TOOLCHAIN_WRAPPER_BUILD
 	$(HOSTCC) $(HOST_CFLAGS) $(TOOLCHAIN_WRAPPER_ARGS) \
 		-s -Wl,--hash-style=$(TOOLCHAIN_WRAPPER_HASH_STYLE) \
-- 
2.22.0