#define STATIC static

每个关键字都有一个小故事

#if     defined(DEBUG_ASSERT)
#define      STATIC
#else
#define      STATIC          static
#endif
backtrace()
  Note that names of "static" functions
       are not exposed, and won't be available in the backtrace.
These functions make some assumptions about how a function's return
       address is stored on the stack.  Note the following:

       *  Omission of the frame pointers (as implied by any of gcc(1)'s
          nonzero optimization levels) may cause these assumptions to be
          violated.

       *  Inlined functions do not have stack frames.

       *  Tail-call optimization causes one stack frame to replace another.

       The symbol names may be unavailable without the use of special linker
       options.  For systems using the GNU linker, it is necessary to use
       the -rdynamic linker option.  Note that names of "static" functions
       are not exposed, and won't be available in the backtrace.