Generate better reference information for member expressions (#14864)

Previously most member expressions only produced the wildcard reference
such as `*.attr` when using the (undocumented) `--export-ref-info` flag.
Use the type of the object to generate better fullnames, such as
`module.Cls.attr`.

mypy/build.py

@@ -2413,7 +2413,9 @@ def finish_passes(self) -> None:
             self.update_fine_grained_deps(self.manager.fg_deps)
 
             if manager.options.export_ref_info:
-                write_undocumented_ref_info(self, manager.metastore, manager.options)
+                write_undocumented_ref_info(
+                    self, manager.metastore, manager.options, self.type_map()
+                )
 
             self.free_state()
             if not manager.options.fine_grained_incremental and not manager.options.preserve_asts:
@@ -3624,7 +3626,9 @@ def is_silent_import_module(manager: BuildManager, path: str) -> bool:
     )
 
 
-def write_undocumented_ref_info(state: State, metastore: MetadataStore, options: Options) -> None:
+def write_undocumented_ref_info(
+    state: State, metastore: MetadataStore, options: Options, type_map: dict[Expression, Type]
+) -> None:
     # This exports some dependency information in a rather ad-hoc fashion, which
     # can be helpful for some tools. This is all highly experimental and could be
     # removed at any time.
@@ -3639,5 +3643,5 @@ def write_undocumented_ref_info(state: State, metastore: MetadataStore, options:
     ref_info_file = ".".join(data_file.split(".")[:-2]) + ".refs.json"
     assert not ref_info_file.startswith(".")
 
-    deps_json = get_undocumented_ref_info_json(state.tree)
+    deps_json = get_undocumented_ref_info_json(state.tree, type_map)
     metastore.write(ref_info_file, json.dumps(deps_json, separators=(",", ":")))

mypy/refinfo.py

@@ -2,13 +2,24 @@
 
 from __future__ import annotations
 
-from mypy.nodes import LDEF, MemberExpr, MypyFile, NameExpr, RefExpr
+from mypy.nodes import LDEF, Expression, MemberExpr, MypyFile, NameExpr, RefExpr
 from mypy.traverser import TraverserVisitor
+from mypy.typeops import tuple_fallback
+from mypy.types import (
+    FunctionLike,
+    Instance,
+    TupleType,
+    Type,
+    TypeType,
+    TypeVarLikeType,
+    get_proper_type,
+)
 
 
 class RefInfoVisitor(TraverserVisitor):
-    def __init__(self) -> None:
+    def __init__(self, type_map: dict[Expression, Type]) -> None:
         super().__init__()
+        self.type_map = type_map
         self.data: list[dict[str, object]] = []
 
     def visit_name_expr(self, expr: NameExpr) -> None:
@@ -23,13 +34,36 @@ def record_ref_expr(self, expr: RefExpr) -> None:
         fullname = None
         if expr.kind != LDEF and "." in expr.fullname:
             fullname = expr.fullname
-        elif isinstance(expr, MemberExpr) and not expr.fullname:
-            fullname = f"*.{expr.name}"
+        elif isinstance(expr, MemberExpr):
+            typ = self.type_map.get(expr.expr)
+            if typ:
+                tfn = type_fullname(typ)
+                if tfn:
+                    fullname = f"{tfn}.{expr.name}"
+            if not fullname:
+                fullname = f"*.{expr.name}"
         if fullname is not None:
             self.data.append({"line": expr.line, "column": expr.column, "target": fullname})
 
 
-def get_undocumented_ref_info_json(tree: MypyFile) -> list[dict[str, object]]:
-    visitor = RefInfoVisitor()
+def type_fullname(typ: Type) -> str | None:
+    typ = get_proper_type(typ)
+    if isinstance(typ, Instance):
+        return typ.type.fullname
+    elif isinstance(typ, TypeType):
+        return type_fullname(typ.item)
+    elif isinstance(typ, FunctionLike) and typ.is_type_obj():
+        return type_fullname(typ.fallback)
+    elif isinstance(typ, TupleType):
+        return type_fullname(tuple_fallback(typ))
+    elif isinstance(typ, TypeVarLikeType):
+        return type_fullname(typ.upper_bound)
+    return None
+
+
+def get_undocumented_ref_info_json(
+    tree: MypyFile, type_map: dict[Expression, Type]
+) -> list[dict[str, object]]:
+    visitor = RefInfoVisitor(type_map)
     tree.accept(visitor)
     return visitor.data