问题
I'm on OS X 10.11, and I have never had problems with linking libraries, but yesterday, out of the blue, I start getting errors when including GSL headers. For instance, I get: "fatal error: 'gsl/gsl_matrix.h' file not found", coming from the line
#include<gsl/gsl_matrix.h>
I then compile with the -lgsl flag, which has worked for the last 6 months, but now suddenly stopped working. GSL is installed through Homebrew, and is located in /usr/local/Cellar/gsl and passing this to the compiler with -I does not help either.
Any idea how this problem could suddenly begin? Brew doctor does not tell me anything useful.
来源：https://stackoverflow.com/questions/33238039/gcc-suddenly-not-finding-gsl-headers