The C11 Standard [ISO/IEC 9899:2011] introduced a new term: temporary lifetime. Modifying an object with temporary lifetime results in undefined behavior (see subclause . According to subclause 6.2.4, paragraph 8).:
A non-lvalue expression with structure or union type, where the structure or union contains a member with array type (including, recursively, members of all contained structures and unions) refers to an object with automatic storage duration and temporary lifetime. Its lifetime begins when the expression is evaluated and its initial value is the value of the expression. Its lifetime ends when the evaluation of the containing full expression or full declarator ends. Any attempt to modify an object with temporary lifetime results in undefined behavior.
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