Rollup merge of #120802 - oli-obk:drop_elab_ice, r=compiler-errors

Bail out of drop elaboration when encountering error types

fixes  #120788

compiler/rustc_mir_dataflow/src/move_paths/builder.rs

@@ -1,7 +1,7 @@
 use rustc_index::IndexVec;
 use rustc_middle::mir::tcx::{PlaceTy, RvalueInitializationState};
 use rustc_middle::mir::*;
-use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt};
 use smallvec::{smallvec, SmallVec};
 
 use std::mem;
@@ -132,6 +132,9 @@ impl<'b, 'a, 'tcx, F: Fn(Ty<'tcx>) -> bool> Gatherer<'b, 'a, 'tcx, F> {
             let body = self.builder.body;
             let tcx = self.builder.tcx;
             let place_ty = place_ref.ty(body, tcx).ty;
+            if place_ty.references_error() {
+                return MovePathResult::Error;
+            }
             match elem {
                 ProjectionElem::Deref => match place_ty.kind() {
                     ty::Ref(..) | ty::RawPtr(..) => {

tests/ui/drop/drop_elaboration_with_errors.rs

@@ -0,0 +1,20 @@
+// can't use build-fail, because this also fails check-fail, but
+// the ICE from #120787 only reproduces on build-fail.
+// compile-flags: --emit=mir
+
+#![feature(type_alias_impl_trait)]
+
+struct Foo {
+    field: String,
+}
+
+type Tait = impl Sized;
+
+fn ice_cold(beverage: Tait) {
+    let Foo { field } = beverage;
+    _ = field;
+}
+
+fn main() {
+    Ok(()) //~ ERROR mismatched types
+}

tests/ui/drop/drop_elaboration_with_errors.stderr

@@ -0,0 +1,14 @@
+error[E0308]: mismatched types
+  --> $DIR/drop_elaboration_with_errors.rs:19:5
+   |
+LL | fn main() {
+   |          - expected `()` because of default return type
+LL |     Ok(())
+   |     ^^^^^^ expected `()`, found `Result<(), _>`
+   |
+   = note: expected unit type `()`
+                   found enum `Result<(), _>`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0308`.