fix[ux]: error messages relating to initializer issues (vyperlang#3831)

fix some error messages related to initializers, to improve UX

---------

Co-authored-by: cyberthirst <[email protected]>

tests/functional/syntax/modules/test_initializers.py

@@ -383,7 +383,7 @@ def foo():
     with pytest.raises(InitializerException) as e:
         compile_code(main, input_bundle=input_bundle)
     assert e.value._message == "`lib2` uses `lib1`, but it is not initialized with `lib1`"
-    assert e.value._hint == "add `lib1` to its initializer list"
+    assert e.value._hint == "did you mean lib2[lib1 := lib1]?"
 
 
 def test_missing_uses(make_input_bundle):
@@ -1228,3 +1228,67 @@ def use_lib1():
         compile_code(main, input_bundle=input_bundle, output_formats=["annotated_ast_dict"])
         is not None
     )
+
+
+def test_hint_for_missing_initializer_in_list(make_input_bundle):
+    lib1 = """
+counter: uint256
+    """
+    lib3 = """
+counter: uint256
+        """
+    lib2 = """
+import lib1
+import lib3
+
+uses: lib1
+uses: lib3
+
+counter: uint256
+
+@internal
+def foo():
+    lib1.counter += 1
+    lib3.counter += 1
+    """
+    main = """
+import lib1
+import lib2
+import lib3
+
+initializes: lib2[lib1:=lib1]
+initializes: lib1
+initializes: lib3
+    """
+    input_bundle = make_input_bundle({"lib1.vy": lib1, "lib2.vy": lib2, "lib3.vy": lib3})
+    with pytest.raises(InitializerException) as e:
+        compile_code(main, input_bundle=input_bundle)
+    assert e.value._message == "`lib2` uses `lib3`, but it is not initialized with `lib3`"
+    assert e.value._hint == "add `lib3 := lib3` to its initializer list"
+
+
+def test_hint_for_missing_initializer_when_no_import(make_input_bundle):
+    lib1 = """
+counter: uint256
+    """
+    lib2 = """
+import lib1
+
+uses: lib1
+
+counter: uint256
+
+@internal
+def foo():
+    lib1.counter += 1
+    """
+    main = """
+import lib2
+
+initializes: lib2
+    """
+    input_bundle = make_input_bundle({"lib1.vy": lib1, "lib2.vy": lib2})
+    with pytest.raises(InitializerException) as e:
+        compile_code(main, input_bundle=input_bundle)
+    assert e.value._message == "`lib2` uses `lib1`, but it is not initialized with `lib1`"
+    assert e.value._hint == "try importing lib1 first"

vyper/semantics/analysis/global_.py

@@ -60,8 +60,12 @@ def _validate_global_initializes_constraint(module_t: ModuleT):
         if u not in all_initialized_modules:
             found_module = module_t.find_module_info(u)
             if found_module is not None:
-                hint = f"add `initializes: {found_module.alias}` to the top level of "
-                hint += "your main contract"
+                # TODO: do something about these constants
+                if str(module_t) in ("<unknown>", "VyperContract.vy"):
+                    module_str = "the top level of your main contract"
+                else:
+                    module_str = f"`{module_t}`"
+                hint = f"add `initializes: {found_module.alias}` to {module_str}"
             else:
                 # CMC 2024-02-06 is this actually reachable?
                 hint = f"ensure `{module_t}` is imported in your main contract!"

vyper/semantics/analysis/module.py

@@ -381,7 +381,13 @@ def validate_initialized_modules(self):
                 msg = "not initialized!"
                 hint = f"add `{s.module_info.alias}.__init__()` to "
                 hint += "your `__init__()` function"
-                err_list.append(InitializerException(msg, s.node, hint=hint))
+
+                # grab the init function AST node for error message
+                # (it could be None, it's ok since it's just for diagnostics)
+                init_func_node = None
+                if module_t.init_function:
+                    init_func_node = module_t.init_function.decl_node
+                err_list.append(InitializerException(msg, init_func_node, s.node, hint=hint))
 
             err_list.raise_if_not_empty()
 
@@ -437,8 +443,10 @@ def visit_UsesDecl(self, node):
         node._metadata["uses_info"] = UsesInfo(used_modules, node)
 
     def visit_InitializesDecl(self, node):
-        module_ref = node.annotation
+        annotation = node.annotation
+
         dependencies_ast = ()
+        module_ref = annotation
         if isinstance(module_ref, vy_ast.Subscript):
             dependencies_ast = vy_ast.as_tuple(module_ref.slice)
             module_ref = module_ref.value
@@ -496,7 +504,23 @@ def visit_InitializesDecl(self, node):
             item = next(iter(used_modules.values()))  # just pick one
             msg = f"`{module_info.alias}` uses `{item.alias}`, but it is not "
             msg += f"initialized with `{item.alias}`"
-            hint = f"add `{item.alias}` to its initializer list"
+
+            lhs = item.alias
+            rhs = None
+            # find the alias of the uninitialized module in this contract
+            # to fill out the error message with.
+            for k, v in self.namespace.items():
+                if isinstance(v, ModuleInfo) and v.module_t == item.module_t:
+                    rhs = k
+                    break
+
+            if rhs is None:
+                hint = f"try importing {item.alias} first"
+            elif not isinstance(annotation, vy_ast.Subscript):
+                # it's `initializes: foo` instead of `initializes: foo[...]`
+                hint = f"did you mean {module_ref.id}[{lhs} := {rhs}]?"
+            else:
+                hint = f"add `{lhs} := {rhs}` to its initializer list"
             raise InitializerException(msg, node, hint=hint)
 
         # note: try to refactor. not a huge fan of mutating the