Annex D (normative) Compatibility features [depr]

D.7 Non-local use of TU-local entities [depr.local]

1
#
A declaration of a non-TU-local entity that is an exposure ([basic.link]) is deprecated.
[ Note
:
Such a declaration in an importable module unit is ill-formed.
— end note
 ]
[ Example
: 
namespace {
  struct A {
    void f() {}
  };
}
A h();                          // deprecated: not internal linkage
inline void g() {A().f();}      // deprecated: inline and not internal linkage
— end example
 ]