c++ - 如何在Mac上进行编译时摆脱此错误？

Question

早上好，
在Mac上编译项目时遇到一些问题。我正在使用Makefile进行编译，当我执行make命令时，出现了错误。问题是，在docker下，编译工作正常，但对于该项目，我需要在mac下编译，因为我使用的是未安装在docker下的库，因此我没有时间时刻。我认为这可能是因为shell使用clang进行编译，而我习惯于使用GCC。我在Mac下是个新手，所以我不知道该怎么做才能避免这种情况。

MY_INFO$ make
c++    -c -o *.o Input.cpp
In file included from Input.cpp:8:
In file included from ./Input.hpp:11:
./Error.hpp:19:9: error: exception specification of overriding function is more lax than base version
        ~Error() = default;
        ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/exception:101:13: note: overridden virtual function is here
    virtual ~exception() _NOEXCEPT;
            ^
In file included from Input.cpp:8:
In file included from ./Input.hpp:11:
./Error.hpp:19:20: warning: defaulted function definitions are a C++11 extension [-Wc++11-extensions]
        ~Error() = default;
                   ^
./Error.hpp:21:17: error: exception specification of overriding function is more lax than base version
    const char *what() const noexcept {return _msg;}
                ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/exception:102:25: note: overridden virtual function is here
    virtual const char* what() const _NOEXCEPT;
                        ^
In file included from Input.cpp:8:
In file included from ./Input.hpp:11:
./Error.hpp:21:29: error: expected ';' at end of declaration list
    const char *what() const noexcept {return _msg;}
                            ^
                            ;
./Error.hpp:18:15: error: member initializer '_msg' does not name a non-static data member or base class
            : _msg(msg), _file(file), _line(line) {}
              ^~~~~~~~~
In file included from Input.cpp:8:
./Input.hpp:18:9: error: exception specification of overriding function is more lax than base version
        ~InputSoundError() = default;
        ^
./Error.hpp:19:9: note: overridden virtual function is here
        ~Error() = default;
        ^
In file included from Input.cpp:8:
./Input.hpp:18:30: warning: defaulted function definitions are a C++11 extension [-Wc++11-extensions]
        ~InputSoundError() = default;
                             ^
2 warnings and 5 errors generated.
make: *** [*.o] Error 1

MY_INFO$ gcc --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/c++/4.2.1
Apple clang version 11.0.3 (clang-1103.0.32.62)
Target: x86_64-apple-darwin19.2.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

如下，我的makefile。

SRC     =   *.cpp
OBJ     =   $(foreach source, $(SRC), $(source:.cpp=.o))
NAME    =   SoundTest
CFLAGS  =   -g -Wall -Wextra -std=c++11
LDFLAGS =   -lportaudio
CC      =   g++
LD      =   g++

all: $(NAME)

$(NAME): $(OBJ)
    $(LD) -o $@ $^ $(LDFLAGS)

obj/%.o: %.cpp
    $(CC) -o $@ -c $^ $(CFLAGS)

clean:
    rm -rf $(OBJ)

fclean: clean
    rm -rf $(NAME)

re: fclean all

Answer 1

您的makefile有一些问题。首先，您不能使用*.cpp来显示文件名-make具有自己的功能，因此您应该使用...

SRC = $(wildcard *.cpp)

您也可以使用类似...的方法检查 SRC变量的值。

$(info SRC=[$(SRC)])

接下来，构建目标文件的规则是...

obj/%.o: %.cpp
    $(CC) -o $@ -c $^ $(CFLAGS)

因此，对于任何给定的源文件 foo.cpp，此规则告诉make如何从该源文件构建 obj/foo.o。但是您可以使用...根据源文件名指定目标文件列表。

OBJ = $(foreach source, $(SRC), $(source:.cpp=.o))

因此，如果 SRC是，例如 a.cpp b.cpp，然后 OBJ是 a.o b.o而不是 obj/a.o obj/b.o，这是使用 obj/%.o: %.cpp规则所必需的。您真正想要的是将 OBJ设为 obj/a.o obj/b.o(例如)，因此变量定义应为...

OBJ = $(patsubst %.cpp,obj/%.o,$(SRC))

将这些位放在一起可以得到...

SRC     =   $(wildcard *.cpp)
OBJ     =   $(patsubst %.cpp,obj/%.o,$(SRC))
NAME    =   SoundTest
CFLAGS  =   -g -Wall -Wextra -std=c++11
LDFLAGS =   -lportaudio
CC      =   g++
LD      =   g++

all: $(NAME)

$(NAME): $(OBJ)
    $(LD) -o $@ $^ $(LDFLAGS)

obj/%.o: %.cpp
    $(CC) -o $@ -c $^ $(CFLAGS)

clean:
    rm -rf $(OBJ)

fclean: clean
    rm -rf $(NAME)

re: fclean all