编译共享库，但其他链接器不工作

Question

我正在尝试编译从 SDL 开发的共享库，所以我正在使用 linkers flags

-lSDL2 -lSDL2_ttf -lm

但在测试时它没有 link

生成文件：

CC  := gcc
CFLAGS  := -Wall -Werror -fPIC  -lSDL2 -lSDL2_ttf -lm
CTFLAGS := -Wall -lSDL2 -lSDL2_ttf -lm -L/home/mz37/programming/MZSDL
LDFLAGS = -shared

RM = rm -f   # rm command
TARGET_LIB = libSGK.so  # target lib

SRCS = src/mzsdl.c src/container.c
OBJS = $(SRCS:.c=.o)

all: ${TARGET_LIB}

test-container.out: ${TARGET_LIB} test/container-test.c
    $(CC) $(CTFLAGS) -o $@ test/container-test.c -lSGK

$(TARGET_LIB): $(OBJS)
    $(CC) ${LDFLAGS} -o $@ $^

$(SRCS:.c=.d):%.d:%.c
    $(CC) $(CFLAGS) -MM $< >$@

include $(SRCS:.c=.d)

clean:
    -${RM} ${TARGET_LIB} ${OBJS} $(SRCS:.c=.d)

以及测试我的文件时的结果 test-container.out:

gcc -Wall -Werror -fPIC  -lSDL2 -lSDL2_ttf -lm -MM src/container.c >src/container.d
gcc -Wall -Werror -fPIC  -lSDL2 -lSDL2_ttf -lm -MM src/mzsdl.c >src/mzsdl.d
gcc -Wall -Werror -fPIC  -lSDL2 -lSDL2_ttf -lm   -c -o src/mzsdl.o src/mzsdl.c
gcc -Wall -Werror -fPIC  -lSDL2 -lSDL2_ttf -lm   -c -o src/container.o src/container.c
gcc -shared -o libSGK.so src/mzsdl.o src/container.o
gcc -Wall    -lSDL2 -lSDL2_ttf -lm -L/home/mz37/programming/MZSDL -o test-container.out  test/container-test.c -lSGK
/usr/bin/ld: /tmp/ccm0XYCK.o: in function `main':
container-test.c:(.text+0x5b): undefined reference to `SDL_Init'
/usr/bin/ld: container-test.c:(.text+0x7a): undefined reference to `TTF_Init'
/usr/bin/ld: container-test.c:(.text+0xb2): undefined reference to `SDL_CreateWindow'
/usr/bin/ld: container-test.c:(.text+0xe9): undefined reference to `SDL_CreateRenderer'
/usr/bin/ld: container-test.c:(.text+0x139): undefined reference to `SDL_CreateRGBSurface'
.....
.....
/usr/bin/ld: /home/mz37/programming/MZSDL/libSGK.so: undefined reference to `SDL_GetError'
/usr/bin/ld: /home/mz37/programming/MZSDL/libSGK.so: undefined reference to `sqrt'
/usr/bin/ld: /home/mz37/programming/MZSDL/libSGK.so: undefined reference to `TTF_RenderText_Blended'
collect2: error: ld returned 1 exit status
make: *** [Makefile:17: test-container.out] Error 1

Answer 1

将 -o test-container.out test/container-test.c 放在 gcc -Wall 之后之前 -l...，顺序是相关的 linker需要知道丢失了哪些符号，它无法提前猜测（至少）container-test

需要什么

将 -lm 放在最后，您确定数学库不需要其他库，但可能其他库需要数学库。

请注意，在执行 link 时只需要 -lm，而不是在编译时（选项 -c）

编译共享库，但其他链接器不工作

complie shared library ,but other linker doesn't work

c

shared-libraries