最近,在我的ubuntu 12.04下,我努力获得一个新的g++
来编译-std=c++11
。
但似乎某些修改也影响了gcc
:
事实是,现在,当我使用gcc
编译时,当我想编译C程序时,它似乎直接(并且没有任何标志)编译C ++程序:
例如:
$ gcc assem.c
assem.c: In function 'int main()':
assem.c:6:13: warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]
char* k = "aa";
void f() {}
int main() {
int a = 0;
double c = 0;
char* k = "aa";
f();
}
版本:
$gcc --version
gcc (Ubuntu 4.8.1-2ubuntu1~12.04) 4.8.1
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
gcc上的别名:
$ alias gcc
bash: alias: gcc : non trouvé
在gcc上:
$ echo `which gcc`
/usr/bin/gcc
我的环境中剩下的可能标志:
$ env | grep FLAG
#nothing
知道问题是什么?
gcc assem.c -v
清楚地表明涉及g ++:
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.8.1-2ubuntu1~12.04' --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.8 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.8.1 (Ubuntu 4.8.1-2ubuntu1~12.04)
COLLECT_GCC_OPTIONS='-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/4.8/cc1plus -quiet -v -imultilib . -imultiarch x86_64-linux-gnu -D_GNU_SOURCE assem.c -quiet -dumpbase assem.c -mtune=generic -march=x86-64 -auxbase assem -version -fstack-protector -o /tmp/ccoeLOQ4.s
GNU C++ (Ubuntu 4.8.1-2ubuntu1~12.04) version 4.8.1 (x86_64-linux-gnu)
compiled by GNU C version 4.8.1, GMP version 5.0.2, MPFR version 3.1.0-p3, MPC version 0.9
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/4.8"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/include/c++/4.8
/usr/include/x86_64-linux-gnu/c++/4.8/.
/usr/include/c++/4.8/backward
/usr/lib/gcc/x86_64-linux-gnu/4.8/include
/usr/local/include
/usr/lib/gcc/x86_64-linux-gnu/4.8/include-fixed
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
GNU C++ (Ubuntu 4.8.1-2ubuntu1~12.04) version 4.8.1 (x86_64-linux-gnu)
compiled by GNU C version 4.8.1, GMP version 5.0.2, MPFR version 3.1.0-p3, MPC version 0.9
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 227d7ccf008db5ae401be7ddcc6b4746
assem.c: In function 'int main()':
assem.c:8:13: warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]
char* k = "aa";
^
COLLECT_GCC_OPTIONS='-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
as -v --64 -o /tmp/ccWfpqbX.o /tmp/ccoeLOQ4.s
GNU assembler version 2.22 (x86_64-linux-gnu) using BFD version (GNU Binutils for Ubuntu) 2.22
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.8/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/4.8/collect2 --sysroot=/ --build-id --eh-frame-hdr -m elf_x86_64 --hash-style=gnu --as-needed -dynamic-linker /lib64/ld-linux-x86-64.so.2 -z relro /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crti.o /usr/lib/gcc/x86_64-linux-gnu/4.8/crtbegin.o -L/usr/lib/gcc/x86_64-linux-gnu/4.8 -L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu -L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../lib -L/lib/x86_64-linux-gnu -L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib -L/usr/lib/gcc/x86_64-linux-gnu/4.8/../../.. /tmp/ccWfpqbX.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/x86_64-linux-gnu/4.8/crtend.o /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crtn.o
$ ls -li /usr/bin/g[c+][c+]
2633166 lrwxrwxrwx 1 root root 21 Oct 10 14:15 /usr/bin/g++ -> /etc/alternatives/g++
2624623 lrwxrwxrwx 1 root root 21 Oct 8 11:38 /usr/bin/gcc -> /etc/alternatives/gcc
$ls -Lli /usr/bin/g[c+][c+]
2650954 -rwxr-xr-x 1 root root 775944 Jun 5 2013 /usr/bin/g++
2650954 -rwxr-xr-x 1 root root 775944 Jun 5 2013 /usr/bin/gcc
$ gcc assem.c -Wstrict-prototypes
cc1plus: warning: command line option '-Wstrict-prototypes' is valid for C/ObjC but not for C++ [enabled by default]
assem.c: In function 'int main()':
assem.c:6:13: warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]
char* k = "aa";
$ ls -li /usr/bin/g[c+][c+]
2633166 lrwxrwxrwx 1 root root 21 Oct 10 14:15 /usr/bin/g++ -> /etc/alternatives/g++
2624623 lrwxrwxrwx 1 root root 21 Oct 8 11:38 /usr/bin/gcc -> /etc/alternatives/gcc
$ls -Lli /usr/bin/g[c+][c+]
2650954 -rwxr-xr-x 1 root root 775944 Jun 5 2013 /usr/bin/g++
2650954 -rwxr-xr-x 1 root root 775944 Jun 5 2013 /usr/bin/gcc
$ ls -l /etc/alternatives/gcc
lrwxrwxrwx 1 root root 16 Oct 10 14:15 /etc/alternatives/gcc -> /usr/bin/g++-4.8
真正的解决方案就是这样做:
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 <priority>
答案 0 :(得分:2)
将评论转换为答案
让我们尝试消除不可能的事情 - 你从中获得了什么:
ls -li /usr/bin/g[c+][c+]
如果涉及符号链接,则还显示以下输出:
ls -Lli /usr/bin/g[c+][c+]
我想知道gcc
二进制文件是否实际上是g++
二进制文件的副本或链接,不知何故。不太可能,除了它会解释你所看到的古怪行为。您也可以尝试选项-Wstrict-prototypes
;它与g++
无效,但与gcc
[...时间过去了......]
gcc -Wstrict-prototypes
的错误消息很有启发性;它强烈建议gcc
以某种方式指向C ++编译器而不是C编译器。
[...更多时间过去了......]
并且有你的答案:inode数字(来自-i
并且是输出中的第一个数字)表明/usr/bin/gcc
和/usr/bin/g++
都指向同一个文件,inode编号2650954.因此,它们都是C ++编译器。
我建议卸载两个编译器并重新安装。这应该解决问题。
或者,如果您有/usr/bin/gcc-4.8
(并且该文件与/usr/bin/g++-4.8
不同),则可以将/etc/alternatives/gcc
更改为指向/usr/bin/gcc-4.8
,而无需重新安装。但总的来说,我建议卸载并重新安装。如果搞砸了,还有什么搞砸了。
请注意,最好将您在问题中显示的所有内容完全保持正确,以免出现任何不一致之处。如果做不到这一点,请仔细编辑所有内容,以免出现不一致。如果存在内部不一致的问题,那么那些试图回答问题的人的生活就会变得复杂 - 我们不知道什么是可信任的,什么是不可信任的。
你的问题很不寻常 - 很不寻常。我没想到发生的事情不太可能发生,但是,正如Sherlock Holmes所说的那样,“我经常告诉你,当你消除了不可能的事物,无论剩下什么,无论多么不可能,都必须是事实吗?“