[jcelerier]

Let me quote the standard then:

    [intro.structure]
    Clause 5 through Clause 15 describe the C++ programming language. 
    That description includes detailed syntactic specifications in a form described in 4.3. 
    For convenience, Annex A repeats all such syntactic specifications.

    Clause 17 through Clause 32 and Annex D (the library clauses) describe the C++ standard library. 
    That description includes detailed descriptions of the entities and macros that constitute the library, in a form described in Clause 16.

it's pretty obvious from that than the library is seen as separate from the language - and yes, std:: could be entirely built-ins but as always that'd be under the as-if rule of optimization.

Else what would be the meaning of core language defects ? http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html

[catblast01]

I think I addressed that: “how they’re organized in the spec”. They’re distinct, but outside of internal references in the spec the distinction between language and library doesn’t really matter. To a user of C++ it’s all one spec with distinctions for freestanding and hosted implementations, etc. You can’t have a conformant C++ implementation without elements from both.

The original point of this thread was about where std::format exists and from a implementation point of view it doesn’t really matter.