Do not ICE in type-alias-impl-trait with save-analysis

src/librustc_typeck/check/mod.rs

@@ -837,8 +837,11 @@ fn has_typeck_tables(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
         return tcx.has_typeck_tables(outer_def_id);
     }
 
-    let id = tcx.hir().as_local_hir_id(def_id).unwrap();
-    primary_body_of(tcx, id).is_some()
+    if let Some(id) = tcx.hir().as_local_hir_id(def_id) {
+        primary_body_of(tcx, id).is_some()
+    } else {
+        false
+    }
 }
 
 fn used_trait_imports(tcx: TyCtxt<'_>, def_id: DefId) -> &DefIdSet {

src/test/ui/save-analysis/issue-68621.rs

@@ -0,0 +1,17 @@
+// compile-flags: -Zsave-analysis
+
+#![feature(type_alias_impl_trait)]
+
+trait Trait {}
+
+trait Service {
+    type Future: Trait;
+}
+
+struct Struct;
+
+impl Service for Struct {
+    type Future = impl Trait; //~ ERROR: could not find defining uses
+}
+
+fn main() {}

src/test/ui/save-analysis/issue-68621.stderr

@@ -0,0 +1,8 @@
+error: could not find defining uses
+  --> $DIR/issue-68621.rs:14:5
+   |
+LL |     type Future = impl Trait;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+