Fix UDT re-exports (microsoft#2137)

Closes microsoft#2122

Author: sezna

compiler/qsc_frontend/src/compile/tests/multiple_packages.rs

@@ -61,6 +61,54 @@ fn multiple_package_check_inner(packages: Vec<(&str, &str)>, expect: Option<&Exp
     }
 }
 
+/// This can be used to test multiple packages which internally have multiple source files, as opposed to the more simple `multiple_package_check`
+/// which only allows one source file per package (for easy and quick test creation).
+fn multiple_package_multiple_source_check(
+    packages: Vec<(&str, Vec<(&str, &str)>)>,
+    expect: Option<&Expect>,
+) {
+    let mut store = PackageStore::new(core());
+    let mut prev_id_and_name: Option<(PackageId, &str)> = None;
+    let num_packages = packages.len();
+    for (ix, (package_name, sources)) in packages.into_iter().enumerate() {
+        let is_last = ix == num_packages - 1;
+        let deps = if let Some((prev_id, prev_name)) = prev_id_and_name {
+            vec![(prev_id, Some(Arc::from(prev_name)))]
+        } else {
+            vec![]
+        };
+
+        let sources = SourceMap::new(
+            sources.iter().map(|(name, source)| {
+                (
+                    Arc::from(format!("{package_name}/{name}.qs")),
+                    Arc::from(*source),
+                )
+            }),
+            None,
+        );
+
+        let unit = compile(
+            &store,
+            &deps[..],
+            sources,
+            TargetCapabilityFlags::all(),
+            LanguageFeatures::default(),
+        );
+
+        match (is_last, &expect) {
+            (true, Some(expect)) => {
+                expect.assert_eq(&format!("{:#?}", unit.errors));
+            }
+            _ => {
+                assert!(unit.errors.is_empty(), "{:#?}", unit.errors);
+            }
+        }
+
+        prev_id_and_name = Some((store.insert(unit), package_name));
+    }
+}
+
 #[test]
 fn namespace_named_main_doesnt_create_main_namespace() {
     multiple_package_check_expect_err(
@@ -509,3 +557,48 @@ fn aliased_export_via_aliased_import() {
         ),
     ]);
 }
+
+#[test]
+fn udt_reexport_with_alias() {
+    multiple_package_multiple_source_check(
+        vec![
+            (
+                "A",
+                vec![
+                    ("FileOne", "struct Foo { content: Bool }"),
+                    ("FileTwo", "export FileOne.Foo as Bar;"),
+                ],
+            ),
+            ("B", vec![("FileThree", "export A.FileTwo.Bar as Baz;")]),
+            (
+                "C",
+                vec![(
+                    "FileFour",
+                    "@EntryPoint()
+            operation Main() : Unit {
+                let x = new B.FileThree.Baz { content = true };
+            }",
+                )],
+            ),
+        ],
+        Some(&expect!["[]"]),
+    );
+}
+
+#[test]
+fn callable_reexport() {
+    multiple_package_check(vec![
+        (
+            "A",
+            "function Foo() : Unit {  }
+                export Foo as Bar;",
+        ),
+        (
+            "B",
+            "           @EntryPoint()
+            operation Main() : Unit {
+                let x = A.A.Bar();
+            }",
+        ),
+    ]);
+}

compiler/qsc_frontend/src/resolve.rs

@@ -1676,10 +1676,10 @@ impl GlobalTable {
                                 .insert_or_find_namespace(ns.iter().map(|s| s.name.clone()));
                         }
                         hir::ItemKind::Ty(..) => {
-                            self.scope
-                                .tys
-                                .get_mut_or_default(namespace)
-                                .insert(global.name.clone(), Res::ExportedItem(item_id, None));
+                            self.scope.tys.get_mut_or_default(namespace).insert(
+                                global.name.clone(),
+                                Res::Item(item_id, ItemStatus::Available),
+                            );
                         }
                         hir::ItemKind::Export(_, _) => {
                             unreachable!("find_item will never return an Export")

compiler/qsc_frontend/src/typeck/convert.rs

@@ -117,13 +117,12 @@ pub(super) fn ty_from_path(names: &Names, path: &Path) -> Ty {
         // So realistically, by construction, `Param` here is unreachable.
         // A path can also never resolve to an export, because in typeck/check,
         // we resolve exports to their original definition.
-        Some(
-            resolve::Res::Local(_) | resolve::Res::Param { .. } | resolve::Res::ExportedItem(_, _),
-        ) => {
-            unreachable!(
-                "A path should never resolve \
+        Some(resolve::Res::Local(_) | resolve::Res::Param { .. }) => unreachable!(
+            " A path should never resolve \
             to a local or a parameter, as there is syntactic differentiation."
-            )
+        ),
+        Some(resolve::Res::ExportedItem(item_id, alias)) => {
+            unreachable!("Exported items should have been resolved to their original definition in type checking. Found {:?} with alias {:?}", item_id, alias);
         }
         None => Ty::Err,
     }