From ca4b7338836edb7325c82f86dccdeb4808cb4a89 Mon Sep 17 00:00:00 2001
From: Mark Pizzolato <mark@infocomm.com>
Date: Wed, 29 Jan 2020 11:39:36 -0800
Subject: [PATCH] makefile: Force gcc/clang -fcommon to address future gcc
 -fno-common default

as reported and discussed in #794
---
 makefile | 7 +++++++
 1 file changed, 7 insertions(+)

--- a/makefile
+++ b/makefile
@@ -506,9 +506,13 @@ else
   ifneq (3,$(GCC_MAJOR_VERSION))
     ifeq (,$(GCC_OPTIMIZERS_CMD))
       GCC_OPTIMIZERS_CMD = $(GCC) --help=optimizers
+      GCC_COMMON_CMD = $(GCC) --help=common
     endif
     GCC_OPTIMIZERS = $(shell $(GCC_OPTIMIZERS_CMD))
   endif
+  ifneq (,$(GCC_COMMON_CMD))
+    GCC_OPTIMIZERS += $(shell $(GCC_COMMON_CMD))
+  endif
   ifneq (,$(findstring $(GCC_VERSION),$(LTO_EXCLUDE_VERSIONS)))
     NO_LTO = 1
   endif
@@ -530,6 +534,9 @@ else
   ifneq (,$(findstring -fstrict-overflow,$(GCC_OPTIMIZERS)))
     CFLAGS_O += -fno-strict-overflow
   endif
+  ifneq (,$(findstring -fcommon,$(GCC_OPTIMIZERS))$(findstring -fno-common,$(GCC_OPTIMIZERS)))
+    CFLAGS_O += -fcommon
+  endif
   ifeq (,$(NO_LTO))
     ifneq (,$(findstring -flto,$(GCC_OPTIMIZERS)))
       CFLAGS_O += -flto -fwhole-program