fix: resolve inference variable before applying adjustments

Author: lowr

crates/hir-ty/src/method_resolution.rs

@@ -541,7 +541,7 @@ pub struct ReceiverAdjustments {
 
 impl ReceiverAdjustments {
     pub(crate) fn apply(&self, table: &mut InferenceTable<'_>, ty: Ty) -> (Ty, Vec<Adjustment>) {
-        let mut ty = ty;
+        let mut ty = table.resolve_ty_shallow(&ty);
         let mut adjust = Vec::new();
         for _ in 0..self.autoderefs {
             match autoderef::autoderef_step(table, ty.clone()) {

crates/hir-ty/src/tests/regression.rs

@@ -1707,3 +1707,19 @@ impl<T, const N: usize> Trait for [T; N] {
         "#,
     );
 }
+
+#[test]
+fn unsize_array_with_inference_variable() {
+    check_types(
+        r#"
+//- minicore: try, slice
+use core::ops::ControlFlow;
+fn foo() -> ControlFlow<(), [usize; 1]> { loop {} }
+fn bar() -> ControlFlow<(), ()> {
+    let a = foo()?.len();
+      //^ usize
+    ControlFlow::Continue(())
+}
+"#,
+    );
+}