Revert "Auto merge of #134330 - scottmcm:no-more-rvalue-len, r=matthewjasper"

This reverts commit e108481f74ff123ad98a63bd107a18d13035b275, reversing
changes made to 303e8bd768526a5812bb1776e798e829ddb7d3ca.

1 files changed, 10 insertions, 0 deletions

diff --git a/compiler/rustc_middle/src/mir/syntax.rs b/compiler/rustc_middle/src/mir/syntax.rs
index bbbaffc5a35..0c17a2e0fe5 100644
--- a/compiler/rustc_middle/src/mir/syntax.rs
+++ b/compiler/rustc_middle/src/mir/syntax.rs
@@ -1351,6 +1351,16 @@ pub enum Rvalue<'tcx> {
     /// model.
     RawPtr(Mutability, Place<'tcx>),
 
+    /// Yields the length of the place, as a `usize`.
+    ///
+    /// If the type of the place is an array, this is the array length. For slices (`[T]`, not
+    /// `&[T]`) this accesses the place's metadata to determine the length. This rvalue is
+    /// ill-formed for places of other types.
+    ///
+    /// This cannot be a `UnOp(PtrMetadata, _)` because that expects a value, and we only
+    /// have a place, and `UnOp(PtrMetadata, RawPtr(place))` is not a thing.
+    Len(Place<'tcx>),
+
     /// Performs essentially all of the casts that can be performed via `as`.
     ///
     /// This allows for casts from/to a variety of types.