From cfacbcb5a23bc26cb913528c372adddabbb33ca1 Mon Sep 17 00:00:00 2001
From: Kevin Traynor <ktraynor@redhat.com>
Date: Thu, 14 May 2020 14:18:57 +0100
Subject: [PATCH] build: disable gcc 10 zero-length-bounds warning
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gcc 10 issues warnings about the use of rearm_data marker
from struct rte_mbuf.

e.g.
../drivers/net/enic/enic_rxtx_vec_avx2.c: In function ‘rx_one’:
../drivers/net/enic/enic_rxtx_vec_avx2.c:21:2:
warning:
array subscript 0 is outside the bounds of an interior zero-length array
‘RTE_MARKER64’ {aka ‘long unsigned int[0]’} [-Wzero-length-bounds]
   21 |  *(uint64_t *)&mb->rearm_data = enic->mbuf_initializer;
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../lib/librte_mbuf/rte_mbuf.h:45,
                 from ../drivers/net/enic/enic_rxtx_vec_avx2.c:6:
../lib/librte_mbuf/rte_mbuf_core.h:484:15:
note: while referencing ‘rearm_data’
  484 |  RTE_MARKER64 rearm_data;
      |

Disable this warning for gcc 10 in order to allow v20.05 to build
without changes to struct rte_mbuf.

Bugzilla ID: 396
Cc: stable@dpdk.org

Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>
---
 config/meson.build           | 4 ++++
 mk/toolchain/gcc/rte.vars.mk | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/config/meson.build b/config/meson.build
index a1c38c053e..43ab113106 100644
--- a/config/meson.build
+++ b/config/meson.build
@@ -208,6 +208,10 @@ warning_flags = [
 	'-Wno-packed-not-aligned',
 	'-Wno-missing-field-initializers'
 ]
+if cc.get_id() == 'gcc' and cc.version().version_compare('>=10.0')
+# FIXME: Bugzilla 396
+	warning_flags += '-Wno-zero-length-bounds'
+endif
 if not dpdk_conf.get('RTE_ARCH_64')
 # for 32-bit, don't warn about casting a 32-bit pointer to 64-bit int - it's fine!!
 	warning_flags += '-Wno-pointer-to-int-cast'
diff --git a/mk/toolchain/gcc/rte.vars.mk b/mk/toolchain/gcc/rte.vars.mk
index f19305e495..928f0e0830 100644
--- a/mk/toolchain/gcc/rte.vars.mk
+++ b/mk/toolchain/gcc/rte.vars.mk
@@ -81,6 +81,11 @@ ifeq ($(shell test $(GCC_VERSION) -lt 47 && echo 1), 1)
 WERROR_FLAGS += -Wno-uninitialized
 endif
 
+ifeq ($(shell test $(GCC_VERSION) -ge 100 && echo 1), 1)
+# FIXME: Bugzilla 396
+WERROR_FLAGS += -Wno-zero-length-bounds
+endif
+
 HOST_WERROR_FLAGS := $(WERROR_FLAGS)
 
 ifeq ($(shell test $(HOST_GCC_VERSION) -gt 70 && echo 1), 1)
-- 
2.20.1