无法让 GLFW 链接

我正在尝试编译以下测试程序：

#include <GL/glfw.h>

int main(int argc, char** argv) {
    if(!glfwInit()) {
        return -1;
    }

    if(!glfwOpenWindow(640, 480, 8, 8, 8, 0, 24, 0, GLFW_WINDOW)) {
        return -1;
    }

    while(glfwGetWindowParam(GLFW_OPENED)) {
        glfwSwapBuffers();
    }

    return 0;
}

但我总是得到undefined reference有关 GLFW 功能的错误。

下面是我的 makefile：

CXX = clang++
CXXFLAGS = -Wall -std=c++0x
LDFLAGS = -lglfw

OBJ_DIR = bin
LIB_DIR = -L/usr/lib
INC_DIR = -I/usr/include

SOURCE = main.cpp
OBJECTS = ${SOURCE:%.cpp=$(OBJ_DIR)/%.o}
EXECUTABLE = hello

all: init $(OBJECTS) $(EXECUTABLE)

$(EXECUTABLE):
    $(CXX) $(CXXFLAGS) $(LDFLAGS) $(LIB_DIR) -o $@ $(OBJECTS)

$(OBJ_DIR)/%.o: %.cpp
    $(CXX) $(INC_DIR) -c $< -o $@

init:
    @mkdir -p "$(OBJ_DIR)"

clean:
    @rm -rf $(OBJ_DIR) $(EXECUTABLE)

我绝对有glfw.h and libglfw.a/.so当我跑步时locate glfw I get:

:~$ locate glfw
/usr/include/GL/glfw.h
/usr/lib/libglfw.a
/usr/lib/libglfw.so
/usr/lib/libglfw.so.2
/usr/lib/libglfw.so.2.6

的输出nm /usr/lib/libglfw.a | grep glfwInit:

:~$ nm /usr/lib/libglfw.a | grep glfwInit
                 U _glfwInitialized
                 U _glfwInitialized
                 U _glfwInitialized
                 U _glfwInitialized
0000000000000000 B _glfwInitialized
0000000000000000 T glfwInit
                 U _glfwInitialized
                 U _glfwInitialized
                 U _glfwInitialized
                 U _glfwInitialized
                 U _glfwInitialized
                 U _glfwInitJoysticks
                 U _glfwInitTimer
00000000000000c0 T _glfwInitJoysticks
0000000000000000 T _glfwInitTimer

以及来自 clang 的详细消息：

clang++ -I/usr/include -c main.cpp -o bin/main.o
clang++ -Wall -std=c++0x -Wl --verbose -lglfw -lGL -lGLU -L/usr/lib -o hello bin/main.o
Ubuntu clang version 3.0-6ubuntu3 (tags/RELEASE_30/final) (based on LLVM 3.0)
Target: x86_64-pc-linux-gnu
Thread model: posix
clang: warning: argument unused during compilation: '-std=c++0x'
 "/usr/bin/ld" -z relro --hash-style=gnu --as-needed --build-id --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o hello /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crt1.o /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crti.o /usr/lib/gcc/x86_64-linux-gnu/4.6/crtbegin.o -L/usr/lib -L/usr/lib/gcc/x86_64-linux-gnu/4.6 -L/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu -L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/4.6/../../.. -L/lib/x86_64-linux-gnu -L/lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib -lglfw -lGL -lGLU bin/main.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-linux-gnu/4.6/crtend.o /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crtn.o
bin/main.o: In function `main':
main.cpp:(.text+0x17): undefined reference to `glfwInit'
main.cpp:(.text+0x76): undefined reference to `glfwOpenWindow'
main.cpp:(.text+0x97): undefined reference to `glfwGetWindowParam'
main.cpp:(.text+0xa7): undefined reference to `glfwSwapBuffers'
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [hello] Error 1

好像没找到图书馆？

问题在于，glfw 库是在依赖于它们的目标文件之前指定给链接器的。ld搜索库以仅解决其正在处理的文件列表中已知的依赖项的依赖项。所以当ld正在寻找libglfw.a它不知道glfwInit依赖于main.o yet. ld（默认情况下）不会返回再次搜索库。

Try:

$(EXECUTABLE):
    $(CXX) $(CXXFLAGS) $(LIB_DIR) -o $@ $(OBJECTS)  $(LDFLAGS)

此外，这些库可能应该在LDLIBS (or LIBS） 多变的 -LDFLAGS通常用于链接器选项：

CXX = clang++
CXXFLAGS = -Wall -std=c++0x
LDLIBS = -lglfw -lGL -lGLU

OBJ_DIR = bin
LIB_DIR = -L/usr/lib
INC_DIR = -I/usr/include

SOURCE = main.cpp
OBJECTS = ${SOURCE:%.cpp=$(OBJ_DIR)/%.o}
EXECUTABLE = hello

all: init $(OBJECTS) $(EXECUTABLE)

$(EXECUTABLE):
    $(CXX) $(LDFLAGS) $(LIB_DIR) -o $@ $(OBJECTS) $(LDLIBS)

$(OBJ_DIR)/%.o: %.cpp
    $(CXX) $(INC_DIR) -c $< -o $@

init:
    @mkdir -p "$(OBJ_DIR)"

clean:
    @rm -rf $(OBJ_DIR) $(EXECUTABLE)