Specify rust-lang/rust#122792

Author: Veykril

src/changelog.rst

@@ -28,6 +28,10 @@ Language changes in Rust 1.82.0
 
 * `Patterns matching empty types can now be omitted in common cases <https://github.com/rust-lang/rust/pull/122792>`_
 
+  * New section: :ref:`fls_mcxF9y5u66sZ`
+
+  * Changed paragraphs: :p:`fls_9fjspnefoyvz`, :p:`fls_uq7ftuuq1sig`, :p:`fls_cfoy86mkmqa4`, :p:`fls_rnppz6y5z8pi`, :p:`fls_x0bmzl1315gq`, :p:`fls_MK83WE0iDqNf`
+
 * `Enforce supertrait outlives obligations when using trait impls <https://github.com/rust-lang/rust/pull/124336>`_
 
   * No change: the concrete type inference resolution is not part of the FLS

src/glossary.rst

@@ -7685,6 +7685,30 @@ visibility modifier
 A :dt:`visibility modifier` sets the :t:`visibility` of the :t:`name` of an
 :t:`item`.
 
+.. _fls_dLlUt8PrXAls:
+
+visible emptiness
+^^^^^^^^^^^^^^^^^
+
+:dp:`fls_shXDYqnUy2Pb`
+:dt:`Visible emptiness <visible emptiness>` is a property of :t:`[type]s` and :t:`[enum variant]s` that have no :t:`[value]s` that are fully observable.
+
+.. _fls_EnT5zRuwviWM:
+
+visible empty enum variant
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+:dp:`fls_MQiPWNwdk95I`
+A :dt:`visible empty enum variant` is an :t:`enum variant` subject to :t:`visible emptiness`.
+
+.. _fls_HYWQ0lJS3TET:
+
+visible empty type
+^^^^^^^^^^^^^^^^^^
+
+:dp:`fls_OLVD0u9w68Gl`
+A :dt:`visible empty type` is a :t:`type` subject to :t:`visible emptiness`.
+
 .. _fls_iplp3gvfbcpw:
 
 weak keyword

src/patterns.rst

@@ -90,12 +90,11 @@ Refutability
 match all possible values of a :t:`type`.
 
 :dp:`fls_9fjspnefoyvz`
-An :t:`irrefutable pattern` is a :t:`pattern` that always matches the :t:`value`
-it is being matched against.
+An :t:`irrefutable pattern` is a :t:`pattern` that always matches any :t:`value` of its :t:`type`.
 
 :dp:`fls_uq7ftuuq1sig`
 A :t:`refutable pattern` is a :t:`pattern` that has a possibility of not
-matching the :t:`value` it is being matched against.
+matching a :t:`value` of a its :t:`type`
 
 :dp:`fls_mnbyt7jfYAZ9`
 A :t:`pattern` that is not an :t:`irrefutable pattern` is a
@@ -385,12 +384,10 @@ to an :t:`associated constant`.
 A :t:`path pattern` is an :t:`irrefutable pattern` when it refers to:
 
 * :dp:`fls_cfoy86mkmqa4`
-  A :t:`constant` whose :t:`type` is an :t:`irrefutable pattern`, or
+  An :t:`irrefutable constant`,
 
 * :dp:`fls_rnppz6y5z8pi`
-  An :t:`enum variant` of an :t:`enum type` with a single :t:`enum variant`
-  where the :t:`[type]s` of all :t:`[field]s` are :t:`[irrefutable pattern]s`,
-  or
+  An :t:`enum variant` of an :t:`enum type` with zero or more :t:`[visibly empty enum variant]s` and one non-:t:`visibly empty enum variant` where the :t:`[type]s` of all :t:`[field]s` are not subject to :t:`visible emptiness`, or
 
 * :dp:`fls_ag6m4mvpturw`
   A :t:`struct` where the :t:`[type]s` of all :t:`[field]s` are
@@ -570,7 +567,7 @@ A :t:`reference pattern` is a :t:`pattern` that dereferences a :t:`pointer` that
 is being matched.
 
 :dp:`fls_x0bmzl1315gq`
-A :t:`reference pattern` is an :t:`irrefutable pattern`.
+A :t:`reference pattern` is an :t:`irrefutable pattern` when its nested :t:`pattern` itself is an :t:`irrefutable pattern`.
 
 :dp:`fls_fedo8zhgpla5`
 The :t:`type` of a :t:`reference pattern` is determined as follows:
@@ -756,7 +753,7 @@ A :t:`struct pattern` is an :t:`irrefutable pattern` if
     A :t:`struct type` or a :t:`union type`, or
 
   * :dp:`fls_MK83WE0iDqNf`
-    An :t:`enum variant` of an :t:`enum` with a single :t:`enum variant`.
+    An :t:`enum variant` of an :t:`enum type` with zero or more :t:`[visibly empty enum variant]s` and one non-:t:`visibly empty enum variant` where the :t:`[type]s` of all :t:`[field]s` are not subject to :t:`visible emptiness`.
 
 .. _fls_nruvg0es3kx7:
 

src/types-and-traits.rst

@@ -2204,6 +2204,53 @@ be modified through :t:`[immutable reference]s`.
 A :t:`type` is subject to :t:`interior mutability` when it contains a
 :std:`core::cell::UnsafeCell`.
 
+.. _fls_mcxF9y5u66sZ:
+
+Visible Emptiness
+~~~~~~~~~~~~~~~~~
+
+.. rubric:: Legality Rules
+
+:dp:`fls_SD4yUEQ9hHa3`
+:t:`Visible emptiness <visible emptiness>` is a property of :t:`[type]s` and :t:`[enum variant]s` that have no :t:`[value]s` that are fully observable.
+
+:dp:`fls_GeoneCP5TYwf`
+A :t:`visible empty type` is a :t:`type` subject to :t:`visible emptiness`.
+
+:dp:`fls_A2W4v53ihTGx`
+A :t:`visible empty enum variant` is an :t:`enum variant` subject to :t:`visible emptiness`.
+
+:dp:`fls_AXOtKdSQR4AF`
+A :t:`type` is subject to :t:`visible emptiness` as follows:
+
+* :dp:`fls_ZfnYORORz40y`
+  The :t:`type` is the :t:`never type`.
+
+* :dp:`fls_TE2GBnZX2YFW`
+  The :t:`type` is a :t:`zero-variant enum type`.
+
+* :dp:`fls_GNFzLMH8RBUC`
+  The :t:`type` is an :t:`enum type` not subject to :t:`attribute` :c:`non_exhaustive` with all :t:`[enum variant]s` are subject to :t:`visible emptiness`.
+
+* :dp:`fls_fSNrRsgzLd0E`
+  The :t:`type` is a :t:`struct type` not subject to :t:`attribute` :c:`non_exhaustive` with at least one :t:`visible <visibility>` :t:`field` whose :t:`type` is subject to :t:`visible emptiness`.
+
+* :dp:`fls_R65LmGTvSlIm`
+  The :t:`type` is a :t:`tuple type` with at least one of the contained :t:`[type]s` is subject to :t:`visible emptiness`.
+
+* :dp:`fls_yiPv3wKYkSRl`
+  The :t:`type` is an :t:`array type` with a non-zero :t:`size operand` and an :t:`element type` that is subject to :t:`visible emptiness`.
+
+
+:dp:`fls_S9QL6yVF5LFI`
+A :t:`enum variant` is subject to :t:`visible emptiness` as follows:
+
+* :dp:`fls_xegU2TFXypcu`
+  The respective :t:`enum type` is not subject to :t:`attribute` :c:`non_exhaustive`.
+
+* :dp:`fls_2CWUWbYT9KcT`
+  The :t:`type` of at least one of the :t:`enum variant`'s visible <visibility> :t:`[field]s` is subject to :t:`visible emptiness`.
+
 .. _fls_lv7w7aalpwm5:
 
 Type Inference