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std::flat_map/std::flat_multimap specializations should be able to share same nested classesSection: 23.6.8.2 [flat.map.defn], 23.6.9.2 [flat.multimap.defn] Status: New Submitter: Jiang An Opened: 2023-07-24 Last modified: 2023-11-03
Priority: 3
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Discussion:
Per current wording, std::flat_map<K, V, C1, KCont, VCont>::containers and
std::flat_multimap<K, V, C2, KCont, VCont>::containers need to be different types
since they are specified as nested classes. Likewise,
std::flat_map<K, V, C, KCont1, VCont1>::value_compare and
std::flat_multimap<K, V, C, KCont2, VCont2>::value_compare also need to be different types.
std::flat_map/std::flat_multimap
specializations share same nested classes.
[2023-11-02; Reflector poll]
Set priority to 3 after reflector poll.
"This would mean we have to care about whether the template parameters are
associated entities of the containers type, for ADL purposes."
"That only matters if you're doing silly things, we shouldn't design the
library with silly people in mind."
"Nobody asked to be able to do this for value_compare in
associative containers, why do we think vendors would take advantage of this
freedom here? NAD."
Proposed resolution:
This wording is relative to N4950.
Add the new paragraph after 23.6.8.2 [flat.map.defn] p1 and 23.6.9.2 [flat.multimap.defn] p1 (twice):
[Drafting note: The intent is to keep the property that key/mapped types, key/mapped containers, and the comparator type are not the associated types of these nested classes during ADL. ]
-?- Implementations may define member types
containersandvalue_compareas nested classes of another templated class and introduce them as typedef-names. Implementations shall ensure that these nested classes are not themselves class templates and have the specified names.