...
In this noncompliant code example, a pointer to an object of nonstandard-layout type is passed to a function that has a "Fortran" language linkage. Language linkages other than "C" and "C++" are conditionally supported with implementation-defined semantics [ISO/IEC 14882-2014]. If the implementation does not support this language linkage, the code is ill-formed. Assuming that the language linkage is supported, any operations performed on the object passed may result in indeterminate behavior, which could have security implications.
...