validate derefer, run derefer inside generator

compiler/rustc_middle/src/mir/mod.rs

@@ -172,12 +172,14 @@ pub enum MirPhase {
     /// terminator means that the auto-generated drop glue will be invoked. Also, `Copy` operands
     /// are allowed for non-`Copy` types.
     DropsLowered = 3,
+    /// After this projections may only contain deref projections as the first element.
+    Derefered = 4,
     /// Beginning with this phase, the following variant is disallowed:
     /// * [`Rvalue::Aggregate`] for any `AggregateKind` except `Array`
     ///
     /// And the following variant is allowed:
     /// * [`StatementKind::SetDiscriminant`]
-    Deaggregated = 4,
+    Deaggregated = 5,
     /// Before this phase, generators are in the "source code" form, featuring `yield` statements
     /// and such. With this phase change, they are transformed into a proper state machine. Running
     /// optimizations before this change can be potentially dangerous because the source code is to
@@ -191,8 +193,8 @@ pub enum MirPhase {
     /// Beginning with this phase, the following variants are disallowed:
     /// * [`TerminatorKind::Yield`](terminator::TerminatorKind::Yield)
     /// * [`TerminatorKind::GeneratorDrop`](terminator::TerminatorKind::GeneratorDrop)
-    GeneratorsLowered = 5,
-    Optimized = 6,
+    GeneratorsLowered = 6,
+    Optimized = 7,
 }
 
 impl MirPhase {