17 Templates [temp]

17.6 Name resolution [temp.res]

17.6.2 Dependent names [temp.dep] Value-dependent expressions [temp.dep.constexpr]

Except as described below, an expression used in a context where a constant expression is required is value-dependent if any subexpression is value-dependent.

An id-expression is value-dependent if:

Expressions of the following form are value-dependent if the unary-expression or expression is type-dependent or the type-id is dependent:

sizeof unary-expression
sizeof ( type-id )
typeid ( expression )
typeid ( type-id )
alignof ( type-id )
noexcept ( expression )

[Note: For the standard library macro offsetof, see [support.types].end note]

Expressions of the following form are value-dependent if either the type-id or simple-type-specifier is dependent or the expression or cast-expression is value-dependent:

simple-type-specifier ( expression-listopt )
static_cast < type-id > ( expression )
const_cast < type-id > ( expression )
reinterpret_cast < type-id > ( expression )
( type-id ) cast-expression

Expressions of the following form are value-dependent:

sizeof ... ( identifier )

An expression of the form &qualified-id where the qualified-id names a dependent member of the current instantiation is value-dependent. An expression of the form &cast-expression is also value-dependent if evaluating cast-expression as a core constant expression succeeds and the result of the evaluation refers to a templated entity that is an object with static or thread storage duration or a member function.