MISRA.SPEC.SAMEFILE

Template specialization and its primary template are declared in different files.

MISRA-C++ Rule 14-7-3 (required): All partial and explicit specializations for a template shall be declared in the same file as the declaration of their primary template.

[NDR 14.5.4(1), 14.6.4.1(7), 14.7.3(6)]

Rationale

It is undefined behaviour if, for a set of template-arguments, an implicit instantiation is generated by the compiler, and a partial or explicit specialization is declared or defined elsewhere in the program that would match the set of template-arguments.

Example

// tmpl.h
template <typename T> void bad_tmpl () {}

template <typename T> void good_tmpl () {}
template <> void good_tmpl<int32_t> () {}

// tmpl.cc
#include "tmpl.h"
template <> void bad_tmpl<int32_t> () {} // Non-compliant
template <> void good_tmpl<int32_t> () {}

// f.cc
#include <tmpl.h>

void f ()
{
   bad_tmpl<int32_t> ();  // implicit instantiation of primary.
                          // explicit instantiation in tmpl.cc would
                          // have been used if it were visible.
   good_tmpl<int32_t> (); // specialization of good_tmpl<int32_t> is
                          // visible with the primary declaration.
}