Add better type deduction to use-dict-union and no-copy-with-merge

pyproject.toml

@@ -126,6 +126,9 @@ target-version = "py310"
 "refurb/visitor/traverser.py" = ["ALL"]
 "test/e2e/gbk.py" = ["FURB105"]
 
+[tool.typos.default.extend-words]
+nd = "nd"
+
 [build-system]
 requires = ["poetry-core>=1.0.0"]
 build-backend = "poetry.core.masonry.api"

refurb/checks/readability/no_copy_with_merge.py

@@ -1,8 +1,8 @@
 from dataclasses import dataclass
 
-from mypy.nodes import CallExpr, Expression, MemberExpr, OpExpr, RefExpr, Var
+from mypy.nodes import CallExpr, Expression, MemberExpr, OpExpr
 
-from refurb.checks.common import is_same_type, stringify
+from refurb.checks.common import get_mypy_type, is_same_type, stringify
 from refurb.error import Error
 
 
@@ -43,13 +43,10 @@ def check_expr(expr: Expression, errors: list[Error]) -> None:
 
     match expr:
         case CallExpr(
-            callee=MemberExpr(
-                expr=RefExpr(node=Var(type=ty)) as ref,
-                name="copy",
-            ),
+            callee=MemberExpr(expr=lhs, name="copy"),
             args=[],
-        ) if is_same_type(ty, dict, set):
-            msg = f"Replace `{stringify(ref)}.copy()` with `{stringify(ref)}`"
+        ) if is_same_type(get_mypy_type(lhs), dict, set):
+            msg = f"Replace `{stringify(lhs)}.copy()` with `{stringify(lhs)}`"
 
             errors.append(ErrorInfo.from_node(expr, msg))
 

refurb/checks/readability/use_dict_union.py

@@ -1,9 +1,9 @@
 from dataclasses import dataclass
 from itertools import groupby
 
-from mypy.nodes import ArgKind, CallExpr, DictExpr, Expression, RefExpr, Var
+from mypy.nodes import ArgKind, CallExpr, DictExpr, Expression, RefExpr
 
-from refurb.checks.common import is_same_type, stringify
+from refurb.checks.common import get_mypy_type, is_same_type, stringify
 from refurb.error import Error
 from refurb.settings import Settings
 
@@ -49,11 +49,7 @@ def add_defaults(settings: dict[str, str]) -> dict[str, str]:
 
 
 def is_builtin_mapping(expr: Expression) -> bool:
-    match expr:
-        case RefExpr(node=Var(type=ty)):
-            return is_same_type(ty, *MAPPING_TYPES)
-
-    return False
+    return is_same_type(get_mypy_type(expr), *MAPPING_TYPES)
 
 
 def check(node: DictExpr | CallExpr, errors: list[Error], settings: Settings) -> None:
@@ -125,6 +121,9 @@ def check(node: DictExpr | CallExpr, errors: list[Error], settings: Settings) ->
                     return
 
                 if kind == ArgKind.ARG_STAR2:
+                    if not is_builtin_mapping(arg):
+                        return
+
                     stringified_arg = stringify(arg)
 
                     if len(node.args) == 1:

test/data/err_173.py

@@ -40,6 +40,12 @@
 _ = dict(x, a=1)
 _ = dict(**x, a=1, b=2)
 _ = dict(**x, **y, a=1, b=2)
+_ = dict(**x, **{})
+
+class Wrapper:
+    d: dict
+
+_ = {**Wrapper().d, **x}
 
 
 # these should not
@@ -66,11 +72,9 @@ def __getitem__(self, key: str) -> Any:
 
 _ = {"k": "v", **c}
 
-# TODO: support more expr types
-_ = {"k": "v", **{}}
-
-
 _ = dict(x)  # noqa: FURB123
 _ = dict(*({},))
 _ = dict()  # noqa: FURB112
 _ = dict(a=1, b=2)
+
+_ = dict(**x, **[])  # type: ignore

test/data/err_173.txt

@@ -20,3 +20,5 @@ test/data/err_173.py:39:5 [FURB173]: Replace `dict(**x, **y)` with `x | y`
 test/data/err_173.py:40:5 [FURB173]: Replace `dict(x, a=1)` with `x | {"a": 1}`
 test/data/err_173.py:41:5 [FURB173]: Replace `dict(**x, a=1, b=2)` with `x | {"a": 1, "b": 2}`
 test/data/err_173.py:42:5 [FURB173]: Replace `dict(**x, **y, a=1, b=2)` with `x | y | {"a": 1, "b": 2}`
+test/data/err_173.py:43:5 [FURB173]: Replace `dict(**x, **{})` with `x | {}`
+test/data/err_173.py:48:5 [FURB173]: Replace `{**Wrapper().d, **x}` with `Wrapper().d | x`

test/data/err_185.py

@@ -11,13 +11,19 @@
 _ = x.copy() | {} | x.copy()
 
 
-
 class C:
-    def copy(self) -> dict:
-        return {}
+    d: dict[str, str]
 
-c = C()
+
+_ = C().d.copy() | {}
 
 
 # these should not
-_ = c.copy() | {}
+
+class NotADict:
+    def copy(self) -> dict:
+        return {}
+
+nd = NotADict()
+
+_ = nd.copy() | {}

test/data/err_185.txt

@@ -4,3 +4,4 @@ test/data/err_185.py:8:5 [FURB185]: Replace `y.copy()` with `y`
 test/data/err_185.py:9:13 [FURB185]: Replace `y.copy()` with `y`
 test/data/err_185.py:11:5 [FURB185]: Replace `x.copy()` with `x`
 test/data/err_185.py:11:21 [FURB185]: Replace `x.copy()` with `x`
+test/data/err_185.py:18:5 [FURB185]: Replace `C().d.copy()` with `C().d`