MISRA.NAMESPACE.UNMD

Unnamed namespace in header file.

MISRA-C++ Rule 7-3-3 (required): There shall be no unnamed namespaces in header files.

Rationale

An unnamed namespace will be unique within each translation unit. Any declarations appearing in an unnamed namespace in a header will refer to different entities in each translation unit, which may not be consistent with developer expectations.

Example

// Header.hpp
namespace // Non-compliant
{
   extern int32_t x;
}
// File1.cpp
#include "Header.hpp"

namespace
{
   int32_t x;
}

void fn_a ( void )
{
   x = 24;
}

// File2.cpp
#include "Header.hpp"

namespace
{
   int32_t x;
}

void fn_b ( void )
{
   fn_a ( );
   if ( x == 24 ) // This x will not have been initialized.
   {
   }
}