Merge 2023-06 LWG Motion 11

P2198R7 Freestanding Feature-Test Macros and Implementation-Defined Extensions

Author: tkoeppe

source/lib-intro.tex

@@ -1470,6 +1470,33 @@
 For each of the headers listed in \tref{headers.cpp.fs},
 a freestanding implementation provides at least
 the freestanding items\iref{freestanding.item} declared in the header.
+
+\pnum
+The \defnadj{hosted}{library facilities} are
+the set of facilities described in this document
+that are required for hosted implementations,
+but not required for freestanding implementations.
+A freestanding implementation provides
+a (possibly empty) implementation-defined subset of
+the hosted library facilities.
+Unless otherwise specified, the requirements on
+each declaration, entity, \grammarterm{typedef-name}, and macro
+provided in this way are the same as
+the corresponding requirements for a hosted implementation,
+except that not all of the members of the namespaces are required to be present.
+
+\pnum
+A freestanding implementation provides
+deleted definitions\iref{dcl.fct.def.delete} for
+a (possibly empty) implementation-defined subset of
+the namespace-scope functions and function templates
+from the hosted library facilities.
+\begin{note}
+An implementation can provide a deleted definition
+so that the result of overload resolution does not silently change
+when migrating a program from a freestanding implementation to
+a hosted implementation.
+\end{note}
 \indextext{implementation!freestanding|)}%
 
 \rSec2[using]{Using the library}