--- coreconf/Werror.mk.orig	2016-02-26 20:51:11 UTC
+++ coreconf/Werror.mk
@@ -5,6 +5,15 @@
 
 # This sets WARNING_CFLAGS for gcc-like compilers.
 
+ifndef CC_IS_CLANG
+  CC_IS_CLANG := $(and $(findstring clang, $(shell $(CC) --version 2>&1)), 1)
+  # Clang claims GCC 4.2.1 compatibility, see GCC_VERSION
+  CC_IS_GCC = 1
+  # Export CC_IS_CLANG and CC_IS_GCC to save a shell invocation when recursing.
+  export CC_IS_CLANG
+  export CC_IS_GCC
+endif
+
 ifndef CC_IS_GCC
   CC_IS_GCC := $(shell $(CC) -x c -E -Wall -Werror /dev/null >/dev/null 2>&1 && echo 1)
   # Export CC_IS_GCC to save a shell invocation when recursing.
@@ -38,7 +47,7 @@ ifndef WARNING_CFLAGS
     disable_warning = $(shell $(CC) -x c -E -Werror -W$(1) /dev/null >/dev/null 2>&1 && echo -Wno-$(1))
 
     WARNING_CFLAGS = -Wall
-    ifeq ($(CC_NAME),clang)
+    ifdef CC_IS_CLANG
       # -Qunused-arguments : clang objects to arguments that it doesn't understand
       #    and fixing this would require rearchitecture
       WARNING_CFLAGS += -Qunused-arguments
@@ -62,10 +71,10 @@ ifndef WARNING_CFLAGS
         NSS_ENABLE_WERROR = 0
         $(warning OS_TARGET is Android, disabling -Werror)
       else
-        ifeq ($(CC_NAME),clang)
+        ifdef CC_IS_CLANG
           # Clang reports its version as an older gcc, but it's OK
           NSS_ENABLE_WERROR = 1
-        else ifeq ($(CC_NAME),gcc)
+        else ifdef CC_IS_GCC
           ifneq (,$(filter 4.8 4.9,$(word 1,$(GCC_VERSION)).$(word 2,$(GCC_VERSION))))
             NSS_ENABLE_WERROR = 1
           endif