继承了一个 C++ 项目。我正在通过 makefile 使用 gcc 4.1.2 在 RHEL 5.5 中构建。该项目很大（数百个文件），总的来说代码非常好。但是，在编译过程中，我经常收到一条 GCC 警告，上面写着：
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/allocator.h: In constructor ‘std::allocator<_Alloc>::allocator() [with _Tp = char]’:
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/allocator.h:97: warning: will never be executed
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/allocator.h:97: warning: will never be executed
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/ext/new_allocator.h: In constructor ‘__gnu_cxx::new_allocator<_Tp>::new_allocator() [with _Tp = char]’:
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/ext/new_allocator.h:65: warning: will never be executed
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/allocator.h: In destructor ‘std::allocator<_Alloc>::~allocator() [with _Tp = char]’:
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/allocator.h:105: warning: will never be executed
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/ext/new_allocator.h: In destructor ‘__gnu_cxx::new_allocator<_Tp>::~new_allocator() [with _Tp = char]’:
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/ext/new_allocator.h:72: warning: will never be executed
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/allocator.h: In copy constructor ‘std::allocator<_Alloc>::allocator(const std::allocator<_Alloc>&) [with _Tp = char]’:
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/allocator.h:100: warning: will never be executed
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/allocator.h:99: warning: will never be executed
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/ext/new_allocator.h: In copy constructor ‘__gnu_cxx::new_allocator<_Tp>::new_allocator(const __gnu_cxx::new_allocator<_Tp>&) [with _Tp = char]’:
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/ext/new_allocator.h:67: warning: will never be executed
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/allocator.h: In destructor ‘std::allocator<_Alloc>::~allocator() [with _Tp = char]’:
/usr/lib/gcc/i386-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/allocator.h:105: warning: will never be executed
它没有给我错误源自的源文件或行号。我要冒昧地说 GCC 的标头很好，所以这里发生了什么？我以前从未遇到过这个特别的警告。