6 Basics [basic]

6.11 Contract assertions [basic.contract]

6.11.1 General [basic.contract.general]

Contract assertions allow the programmer to specify properties of the state of the program that are expected to hold at certain points during execution.

Contract assertions are introduced by precondition-specifier s, postcondition-specifier s ([dcl.contract.func]), and assertion-statement s ([stmt.contract.assert]).

Each contract assertion has a contract-assertion predicate, which is an expression of type bool.

[Note 1 :

The value of the predicate is used to identify program states that are expected.

— end note]

An invocation of the macro va_start ([cstdarg.syn]) shall not be a subexpression of the predicate of a contract assertion, no diagnostic required.

[Note 2 :

Within the predicate of a contract assertion, id-expression s referring to variables declared outside the contract assertion are const ([expr.prim.id.unqual]), this is a pointer to const ([expr.prim.this]), and the result object can be named if a result-name-introducer ([dcl.contract.res]) has been specified.

— end note]