fix[lang]: builtin type comparisons (vyperlang#3956)

prior to this commit, due to re-loading and re-analysing the builtin
modules, the types defined in those modules do not compare when they are
imported in different files. this commit globally(!) caches the builtin
modules, ensuring builtin types compare correctly no matter how they are
imported. the global scope should be safe, since builtins are always
stable across compilations.

tests/functional/codegen/modules/test_interface_imports.py

@@ -29,3 +29,32 @@ def test_foo(s: ifaces.IFoo) -> bool:
     c = get_contract(contract, input_bundle=input_bundle)
 
     assert c.test_foo(foo.address) is True
+
+
+def test_import_interface_types_stability(make_input_bundle, get_contract):
+    lib1 = """
+from ethereum.ercs import IERC20
+    """
+    lib2 = """
+from ethereum.ercs import IERC20
+    """
+
+    main = """
+import lib1
+import lib2
+
+from ethereum.ercs import IERC20
+
+@external
+def foo() -> bool:
+    # check that this typechecks both directions
+    a: lib1.IERC20 = IERC20(msg.sender)
+    b: lib2.IERC20 = IERC20(msg.sender)
+
+    # return the equality so we can sanity check it
+    return a == b
+    """
+    input_bundle = make_input_bundle({"lib1.vy": lib1, "lib2.vy": lib2})
+    c = get_contract(main, input_bundle=input_bundle)
+
+    assert c.foo() is True

vyper/semantics/analysis/module.py

@@ -10,6 +10,7 @@
     FileInput,
     FilesystemInputBundle,
     InputBundle,
+    PathLike,
 )
 from vyper.evm.opcodes import version_check
 from vyper.exceptions import (
@@ -398,7 +399,7 @@ def _ast_from_file(self, file: FileInput) -> vy_ast.Module:
         # two ASTs produced from the same source
         ast_of = self.input_bundle._cache._ast_of
         if file.source_id not in ast_of:
-            ast_of[file.source_id] = _parse_and_fold_ast(file)
+            ast_of[file.source_id] = _parse_ast(file)
 
         return ast_of[file.source_id]
 
@@ -870,7 +871,7 @@ def _load_import_helper(
         raise ModuleNotFound(module_str, hint=hint) from err
 
 
-def _parse_and_fold_ast(file: FileInput) -> vy_ast.Module:
+def _parse_ast(file: FileInput) -> vy_ast.Module:
     module_path = file.resolved_path  # for error messages
     try:
         # try to get a relative path, to simplify the error message
@@ -910,6 +911,9 @@ def _is_builtin(module_str):
     return any(module_str.startswith(prefix) for prefix in BUILTIN_PREFIXES)
 
 
+_builtins_cache: dict[PathLike, tuple[CompilerInput, ModuleT]] = {}
+
+
 def _load_builtin_import(level: int, module_str: str) -> tuple[CompilerInput, InterfaceT]:
     if not _is_builtin(module_str):
         raise ModuleNotFound(module_str)
@@ -933,6 +937,13 @@ def _load_builtin_import(level: int, module_str: str) -> tuple[CompilerInput, In
 
     path = _import_to_path(level, remapped_module).with_suffix(".vyi")
 
+    # builtins are globally the same, so we can safely cache them
+    # (it is also *correct* to cache them, so that types defined in builtins
+    # compare correctly using pointer-equality.)
+    if path in _builtins_cache:
+        file, module_t = _builtins_cache[path]
+        return file, module_t.interface
+
     try:
         file = input_bundle.load_file(path)
         assert isinstance(file, FileInput)  # mypy hint
@@ -946,9 +957,10 @@ def _load_builtin_import(level: int, module_str: str) -> tuple[CompilerInput, In
             hint = f"try renaming `{module_prefix}` to `I{module_prefix}`"
         raise ModuleNotFound(module_str, hint=hint) from e
 
-    # TODO: it might be good to cache this computation
-    interface_ast = _parse_and_fold_ast(file)
+    interface_ast = _parse_ast(file)
 
     with override_global_namespace(Namespace()):
         module_t = _analyze_module_r(interface_ast, input_bundle, ImportGraph(), is_interface=True)
+
+    _builtins_cache[path] = file, module_t
     return file, module_t.interface

vyper/semantics/types/module.py

@@ -127,7 +127,7 @@ def _is_function_implemented(fn_name, fn_type):
                 continue
 
             if not _is_function_implemented(name, type_):
-                unimplemented.append(name)
+                unimplemented.append(type_._pp_signature)
 
         if len(unimplemented) > 0:
             # TODO: improve the error message for cases where the