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[contents]
16 Library introduction [library]
16.4 Library-wide requirements [requirements]
16.4.2 Library contents and organization [organization]
16.4.2.2 Library contents [contents]
The C++ standard library provides definitions for the entities and macros described in the synopses of the C++ standard library headers ([headers]), unless otherwise specified.
All library entities exceptoperator new andoperator delete are defined within the namespacestd or namespaces nested within namespacestd.142
It is unspecified whether names declared in a specific namespace are declared directly in that namespace or in an inline namespace inside that namespace.143
Whenever an unqualified name other thanswap, make_error_code, make_error_condition,from_stream, orsubmdspan_mapping is used in the specification of a declaration D in [support] through [exec] or [depr], its meaning is established as-if by performing unqualified name lookup ([basic.lookup.unqual]) in the context of D.
[Note 1:
Argument-dependent lookup is not performed.
â end note]
Similarly, the meaning of a qualified-id is established as-if by performing qualified name lookup ([basic.lookup.qual]) in the context of D.
[Example 1:
The reference to is_array_v in the specification of std::to_array ([array.creation]) refers to ::std::is_array_v.
â end example]
[Note 2:
Operators in expressions ([over.match.oper]) are not so constrained; see [global.functions].
â end note]
The meaning of the unqualified name swap is established in an overload resolution context for swappable values ([swappable.requirements]).
The meanings of the unqualified namesmake_error_code, make_error_condition,from_stream, andsubmdspan_mapping are established as-if by performing argument-dependent lookup ([basic.lookup.argdep]).
The C standard library headers ([support.c.headers]) also define names within the global namespace, while the C++ headers for C library facilities ([headers]) can also define names within the global namespace.
This gives implementers freedom to use inline namespaces to support multiple configurations of the library.