[temp.dep.constexpr] (original) (raw)

13 Templates [temp]

13.8 Name resolution [temp.res]

13.8.3 Dependent names [temp.dep]

13.8.3.4 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.

Anid-expressionis value-dependent if

• it is a concept-id and its concept-name is dependent or any of its arguments are dependent ([temp.dep.temp]),
• it is type-dependent,
• it is the name of a constant template parameter,
• it is a name introduced by the for-range-declarationof an expansion-statement ([stmt.expand]),
• it names a static data member that is a dependent member of the current instantiation and is not initialized in a member-declarator,
• it names a static member function that is a dependent member of the current instantiation, or
• it names a potentially-constant variable ([expr.const]) that is initialized with an expression that is value-dependent.

Expressions of the following form are value-dependent:

unless the identifier is a structured binding pack whose initializer is not dependent.

An expression of the form &qualified-id where thequalified-id names a dependent member of the current instantiation is value-dependent.

An expression of the form &cast-expressionis also value-dependent if evaluating cast-expressionas 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.

A reflect-expression is value-dependent if

• it is of the form ^^reflection-name and the reflection-name
  • is a dependent qualified name,
  • is a dependent namespace-name,
  • is the name of a template parameter, or
  • names a dependent member of the current instantiation ([temp.dep.type]),
• it is of the form ^^type-id and the type-id denotes a dependent type, or
• it is of the form ^^id-expression and the id-expression is value-dependent.