manage_multi_threading EIGEN_UNUSED generates warning

Submitted by Pablo Hernández

Assigned to Nobody

Link to original bugzilla bug (#1689)
Operating system: Mac OS

Description

Workaround to solve a warning is generating another warning, but his tiem the warning is correct, the warning is marked as unused, but used.

Core/products/Parallelizer.h:25:5: warning: 'm_maxThreads' was marked unused but was used [-Wused-but-marked-unused]

inline void manage_multi_threading(Action action, int* v)  
{  
  static EIGEN_UNUSED int m_maxThreads = -1;  
  
  if(action==SetAction)  
  {  
    eigen_internal_assert(v!=0);  
    m_maxThreads = *v;  
  }  

The compiler and some flags: Mac10.10-AppleClang-dbg-x86_64-static

ci results here: https://open.cdash.org/viewBuildError.php?type=1&buildid=5785448