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In this noncompliant code example, the variable v is defined in an unnamed namespace within a header file, and an inline function, get_v(), is defined, which accesses that variable. ODR-using the inline function from multiple translation units (as shown in the implementation of f() and g()) violates the one-definition rule because the definition of get_v() is not identical in all translation units ( due to referencing a unique v in each translation unit).

// a.h
#ifndef A_HEADER_FILE
#define A_HEADER_FILE
 
namespace {
int v;
}
 
inline int get_v() { return v; }
 
#endif // A_HEADER_FILE
 
// a.cpp
#include "a.h"
 
void f() {
  int i = get_v();
  // ...
}
 
// b.cpp
#include "a.h"
 
void g() {
  int i = get_v();
  // ...
}

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