Hello all,

I build qemu with fuzzing enabled using clang and following error come.

nbd/server.c:1937:1: error: unused function 
'glib_listautoptr_cleanup_NBDExtentArray' [-Werror,-Wunused-function]
G_DEFINE_AUTOPTR_CLEANUP_FUNC(NBDExtentArray, nbd_extent_array_free);
^
/usr/include/glib-2.0/glib/gmacros.h:462:22: note: expanded from macro 
'G_DEFINE_AUTOPTR_CLEANUP_FUNC'
  static inline void _GLIB_AUTOPTR_LIST_FUNC_NAME(TypeName) (GList **_l) { 
g_list_free_full (*_l, (GDestroyNotify) func); } \
                     ^
/usr/include/glib-2.0/glib/gmacros.h:443:48: note: expanded from macro 
'_GLIB_AUTOPTR_LIST_FUNC_NAME'
#define _GLIB_AUTOPTR_LIST_FUNC_NAME(TypeName) 
glib_listautoptr_cleanup_##TypeName
                                               ^
<scratch space>:170:1: note:   CC      crypto/hash-glib.o
expanded from here
glib_listautoptr_cleanup_NBDExtentArray
^
nbd/server.c:1937:1: error: unused function 
'glib_slistautoptr_cleanup_NBDExtentArray' [-Werror,-Wunused-function]
/usr/include/glib-2.0/glib/gmacros.h:463:22: note: expanded from macro 
'G_DEFINE_AUTOPTR_CLEANUP_FUNC'
  static inline void _GLIB_AUTOPTR_SLIST_FUNC_NAME(TypeName) (GSList **_l) { 
g_slist_free_full (*_l, (GDestroyNotify) func); } \
                     ^
/usr/include/glib-2.0/glib/gmacros.h:445:49: note: expanded from macro 
'_GLIB_AUTOPTR_SLIST_FUNC_NAME'
#define _GLIB_AUTOPTR_SLIST_FUNC_NAME(TypeName) 
glib_slistautoptr_cleanup_##TypeName
                                                ^
<scratch space>:171:1: note: expanded from here
glib_slistautoptr_cleanup_NBDExtentArray


I see Eric’s patch 9bda600b083(“build: Silence clang warning on older glib 
autoptr usage”)
So I know there should be a ‘-Wno-unused-function’ in CFLAGS. It is after 
./configure:

CFLAGS            -g  -Wno-unused-function
QEMU_CFLAGS       -I/usr/include/pixman-1  -Werror  -pthread 
-I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -fPIE 
-DPIE -m64 -mcx16 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE 
-Wstrict-prototypes -Wredundant-decls -Wall -Wundef -Wwrite-strings 
-Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv -std=gnu99  
-Wno-string-plus-int -Wno-typedef-redefinition -Wno-initializer-overrides 
-Wexpansion-to-defined -Wendif-labels -Wno-shift-negative-value 
-Wno-missing-include-dirs -Wempty-body -Wnested-externs -Wformat-security 
-Wformat-y2k -Winit-self -Wignored-qualifiers -Wold-style-definition 
-Wtype-limits -fstack-protector-strong -I$(SRC_PATH)/capstone/include

However while I ‘make V=1’ I see the build nbd/serer.c using following command:
clang-8 -iquote /home/test/qemu/nbd -iquote nbd -iquote 
/home/test/qemu/tcg/i386 -isystem /home/test/qemu/linux-headers -isystem 
/home/test/qemu/linux-headers -iquote . -iquote /home/test/qemu -iquote 
/home/test/qemu/accel/tcg -iquote /home/test/qemu/include -iquote 
/home/test/qemu/disas/libvixl -I/usr/include/pixman-1  -Werror  -pthread 
-I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -fPIE 
-DPIE -m64 -mcx16 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE 
-Wstrict-prototypes -Wredundant-decls -Wall -Wundef -Wwrite-strings 
-Wmissing-prototypes -fno-strict-aliasing -fno-common -fwrapv -std=gnu99  
-Wno-string-plus-int -Wno-typedef-redefinition -Wno-initializer-overrides 
-Wexpansion-to-defined -Wendif-labels -Wno-shift-negative-value 
-Wno-missing-include-dirs -Wempty-body -Wnested-externs -Wformat-security 
-Wformat-y2k -Winit-self -Wignored-qualifiers -Wold-style-definition 
-Wtype-limits -fstack-protector-strong -I/home/test/qemu/capstone/include 
-I/home/test/qemu/tests -I/home/test/qemu/tests/qtest -MMD -MP -MT nbd/server.o 
-MF nbd/server.d -fsanitize=address,fuzzer-no-link  -c -o nbd/server.o 
nbd/server.c

There’s no CFLAGS ‘-Wno-unused-function’.

So I want to know:
1. Wha’t the relation of CFLAGS and QEMU_CFLAGS, it seems the CFLAGS doesn’t 
work in this.
2. Any hits to solve this? My env error or needs a patch?

I use following command in Ubuntu 18.04.1.
CC=clang-8 CXX=clang++-8  ./configure  --target-list="i386-softmmu"  
--enable-debug --enable-debug  --enable-kvm --enable-fuzzing


Thanks,
Li Qiang

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