c - Linker error building OpenWrt package - c

Question

I'm building a little OpenWRT application and I want to statically link a library to it.
EDIT: This happens with other libraries as well, not only libcurl.
I'm getting this error while building it:
make[3]: Entering directory `/home/md/work/openwrt/build_dir/target-mips_r2_uClibc-0.9.33.2/app'
mips-openwrt-linux-uclibc-gcc -c -Os -pipe -mips32r2 -mtune=34kc -mno-branch-likely -fno-caller-saves -fhonour-copts -Wno-error=unused-but-set-variable -msoft-float -Wall -Werror main.c -o main.o
mips-openwrt-linux-uclibc-gcc -Os -pipe -mips32r2 -mtune=34kc -mno-branch-likely -fno-caller-saves -fhonour-copts -Wno-error=unused-but-set-variable -msoft-float -Wall -Werror -L/home/md/work/openwrt/staging_dir/target-mips_r2_uClibc-0.9.33.2/usr/lib -L/home/md/work/openwrt/staging_dir/target-mips_r2_uClibc-0.9.33.2/lib -L/home/md/work/openwrt/staging_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33.2/usr/lib -L/home/md/work/openwrt/staging_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33.2/lib -Wl,-Bstatic -lcurl main.o -o app
/home/md/work/openwrt/staging_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33.2/lib/gcc/mips-openwrt-linux-uclibc/4.6.4/../../../../mips-openwrt-linux-uclibc/bin/ld: cannot find -lgcc_s
/home/md/work/openwrt/staging_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33.2/lib/gcc/mips-openwrt-linux-uclibc/4.6.4/../../../../mips-openwrt-linux-uclibc/bin/ld: cannot find -lgcc_s
collect2: ld returned 1 exit status
make[3]: *** [app] Error 1
It's weird, because I have libgcc_s.so on the search path:
stormbreaker:openwrt> find . -name libgcc_s.*
./build_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33.2/uClibc-0.9.33.2/libc/sysdeps/linux/common/libgcc_s.h
./build_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33.2/gcc-linaro-4.6-2012.12-final/gcc/libgcc_s.so
./build_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33.2/gcc-linaro-4.6-2012.12-final/gcc/libgcc_s.so.1
./build_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33.2/gcc-linaro-4.6-2012.12-final/mips-openwrt-linux-uclibc/libgcc/libgcc_s.so
./build_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33.2/gcc-linaro-4.6-2012.12-final/mips-openwrt-linux-uclibc/libgcc/libgcc_s.so.1
./build_dir/target-mips_r2_uClibc-0.9.33.2/toolchain/ipkg-ar71xx/libgcc/lib/libgcc_s.so.1
./build_dir/target-mips_r2_uClibc-0.9.33.2/toolchain/libgcc_s.so.1
./staging_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33.2/lib/libgcc_s.so
./staging_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33.2/lib/libgcc_s.so.1
./staging_dir/target-mips_r2_uClibc-0.9.33.2/root-ar71xx/lib/libgcc_s.so
./staging_dir/target-mips_r2_uClibc-0.9.33.2/root-ar71xx/lib/libgcc_s.so.1
I tried some hacks with -rpath and -rpath-link, but got the same result. As far as I know, libcurl doesn't need libgcc_s.
I created a simple case to reproduce this:
The relevant part of openwrt/package/app/Makefile:
TARGET_CFLAGS += -Wall -Werror
TARGET_LIBS = -Wl,-Bstatic -lcurl
define Build/Compile
CC="$(TARGET_CC)" \
CFLAGS="$(TARGET_CFLAGS)" \
LDFLAGS="$(TARGET_LDFLAGS)" \
LIBS="$(TARGET_LIBS)" \
$(MAKE) -C $(PKG_BUILD_DIR)
endef
openwrt/package/app/src/Makefile:
APP = app
SOURCES = $(wildcard *.c)
OBJECTS = $(SOURCES:.c=.o)
$(APP): $(OBJECTS)
$(CC) $(CFLAGS) $(LDFLAGS) $(LIBS) $(OBJECTS) -o $(APP)
# Objects
%.o: %.c
$(CC) -c $(CFLAGS) $< -o $#
The application itself is a single file:
#include <stdio.h>
#include <curl/curl.h>
int main (void)
{
curl_global_init(CURL_GLOBAL_ALL);
printf("Ok!\n");
return 0;
}

Answer 1

Increasing the verbosity of the linker (using -Wl,--verbose=99) gave me these clues:
...
attempt to open /home/md/work/openwrt/staging_dir/target-mips_r2_uClibc-0.9.33/usr/lib/libgcc_s.a failed
attempt to open /home/md/work/openwrt/staging_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33/lib/gcc/mips-openwrt-linux-uclibc/4.6.3/libgcc_s.a failed
attempt to open /home/md/work/openwrt/staging_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33/lib/gcc/mips-openwrt-linux-uclibc/4.6.3/../../../../mips-openwrt-linux-uclibc/lib/libgcc_s.a failed
attempt to open /home/md/work/openwrt/staging_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33/mips-openwrt-linux-uclibc/bin/../../../toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33/usr/local/lib/libgcc_s.a failed
attempt to open /home/md/work/openwrt/staging_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33/mips-openwrt-linux-uclibc/bin/../../../toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33/lib/libgcc_s.a failed
attempt to open /home/md/work/openwrt/staging_dir/toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33/mips-openwrt-linux-uclibc/bin/../../../toolchain-mips_r2_gcc-4.6-linaro_uClibc-0.9.33/usr/lib/libgcc_s.a failed
etc.
Looks like the static version of libgcc_s is missing.
Anyway, I changed my package Makefile to:
TARGET_LIBS = -Wl,-Bdynamic -lgcc_s \
-Wl,-Bstatic -lcurl
define Build/Compile
$(TARGET_CONFIGURE_OPTS) \
CFLAGS="$(TARGET_CFLAGS)" \
LDFLAGS="$(TARGET_LDFLAGS)" \
LIBS="$(TARGET_LIBS)" \
$(MAKE) -C $(PKG_BUILD_DIR)
endef
Works for me =)
I understand why linking with a static library would need a static version of its dependencies, But I wasn't expecting the linker to do it behind my back, without falling back the dynamic version first.