[#mp_units-get_quantity_spec-068]
= xref:mp_units.adoc[mp_units]::get_quantity_spec
:relfileprefix: ../
:mrdocs:

== Synopsis

Declared in `<mp‐units/framework/unit_definitions.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<xref:mp_units/Unit.adoc[Unit] U>
requires std::is_final_v<decltype(detail::get_associated_quantity(U{}))>
[[deprecated("2.6.0: `quantity_spec` definition of `U` should not be marked `final`"), nodiscard]]
consteval
xref:mp_units/QuantitySpec.adoc[QuantitySpec] auto
get_quantity_spec(U);
----

[WARNING]
====
https://en.cppreference.com/cpp/language/attributes/deprecated[Deprecated^]: 2.6.0: `quantity_spec` definition of `U` should not be marked `final`. Use of this entity is allowed but discouraged.
====
[NOTE]
====
This function is a https://en.cppreference.com/w/cpp/language/friend[hidden friend] of xref:mp_units/one-0f.adoc[one], declared inside an implementation-defined base class: it can be found only through argument-dependent lookup.
====

== Return Value

[NOTE]
====
The return value https://en.cppreference.com/cpp/language/attributes/nodiscard[should not be discarded^].
====

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