reject weird exports of value types

also add a test for an exception case that was not tested before

tests/functional/syntax/modules/test_exports.py

@@ -485,3 +485,36 @@ def an_internal_function():
     # as_posix() for windows
     lib1_path = (tmp_path / "lib1.vy").as_posix()
     assert e.value._message == f"lib1 (located at `{lib1_path}`) has no external functions!"
+
+
+def test_invalid_export(make_input_bundle):
+    lib1 = """
+@external
+def foo():
+    pass
+    """
+    main = """
+import lib1
+a: address
+
+exports: lib1.__interface__(self.a).foo
+    """
+    input_bundle = make_input_bundle({"lib1.vy": lib1})
+
+    with pytest.raises(StructureException) as e:
+        compile_code(main, input_bundle=input_bundle)
+
+    assert e.value._message == "invalid export of a value"
+    assert e.value._hint == "exports should look like <module>.<function | interface>"
+
+    main = """
+interface Foo:
+    def foo(): nonpayable
+
+exports: Foo
+    """
+    with pytest.raises(StructureException) as e:
+        compile_code(main)
+
+    assert e.value._message == "invalid export"
+    assert e.value._hint == "exports should look like <module>.<function | interface>"

vyper/semantics/analysis/module.py

@@ -40,7 +40,7 @@
 )
 from vyper.semantics.data_locations import DataLocation
 from vyper.semantics.namespace import Namespace, get_namespace, override_global_namespace
-from vyper.semantics.types import EventT, FlagT, InterfaceT, StructT, is_type_t
+from vyper.semantics.types import TYPE_T, EventT, FlagT, InterfaceT, StructT, is_type_t
 from vyper.semantics.types.function import ContractFunctionT
 from vyper.semantics.types.module import ModuleT
 from vyper.semantics.types.utils import type_from_annotation
@@ -499,6 +499,14 @@ def visit_ExportsDecl(self, node):
                     raise StructureException("not a public variable!", decl, item)
                 funcs = [decl._expanded_getter._metadata["func_type"]]
             elif isinstance(info.typ, ContractFunctionT):
+                # e.g. lib1.__interface__(self._addr).foo
+                if not isinstance(get_expr_info(item.value).typ, (ModuleT, TYPE_T)):
+                    raise StructureException(
+                        "invalid export of a value",
+                        item.value,
+                        hint="exports should look like <module>.<function | interface>",
+                    )
+
                 # regular function
                 funcs = [info.typ]
             elif is_type_t(info.typ, InterfaceT):