[catblast01]

This is really a false/meaningless distinction though. The C++ spec covers the “language” (it’s one of the first sentences), and that includes the standard library. The spec uses the terminology language and library but there is no formal distinction between them other than how they’re organized in the spec. A conformant compiler could implement the entire STL as a built in if it wanted to.

There is a formal distinction between hosted and freestanding, but that’s not the same as library/language. Cf https://en.cppreference.com/w/cpp/freestanding

I really don’t care for pedantry, but when people start correcting others then had better be right.

[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.