我有一个问题,当g在c 11模式下运行时,一些预处理器宏未扩展正确.这使我在使用Qt编译程序时遇到麻烦.
$g++ --version g++ (GCC) 4.7.2 Copyright (C) 2012 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.
以下剪辑揭示了问题：
$cat foo.cpp
//#include <QtGui>
#define QTOSTRING_HELPER(s) #s
#define QTOSTRING(s) QTOSTRING_HELPER(s)
#ifndef QT_NO_DEBUG
# define QLOCATION "\0"__FILE__":"QTOSTRING(__LINE__)
# define METHOD(a) qFlagLocation("0"#a QLOCATION)
# define SLOT(a) qFlagLocation("1"#a QLOCATION)
# define SIGNAL(a) qFlagLocation("2"#a QLOCATION)
#else
# define METHOD(a) "0"#a
# define SLOT(a) "1"#a
# define SIGNAL(a) "2"#a
#endif
METHOD(grml)
在没有c 11的情况下对其进行预处理是正确的.
$g++ -E foo.cpp
# 1 "foo.cpp"
# 1 "<command-line>"
# 1 "foo.cpp"
# 15 "foo.cpp"
qFlagLocation("0""grml" "\0""foo.cpp"":""15")
但是在C 11模式下,QTOSTRING宏不会扩展,导致源代码行出现编译错误.
$g++ -std=c++11 -E foo.cpp
# 1 "foo.cpp"
# 1 "<command-line>"
# 1 "foo.cpp"
# 15 "foo.cpp"
qFlagLocation("0""grml" "\0"__FILE__":"QTOSTRING(15))
这种行为是否有意,我该怎么做才能启用扩展？
