From 6d8c84bde912ef203c7a8e31910c0cede935560e Mon Sep 17 00:00:00 2001
From: David Peter <sharkdp@users.noreply.github.com>
Date: Tue, 8 Jul 2025 14:21:20 +0200
Subject: [PATCH 1/2] [ty] Clarify diagnostic message (#19203)

This diagnostic message was missing the word "type"
---
 crates/ty_python_semantic/resources/mdtest/attributes.md | 2 +-
 crates/ty_python_semantic/src/types/infer.rs             | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/crates/ty_python_semantic/resources/mdtest/attributes.md b/crates/ty_python_semantic/resources/mdtest/attributes.md
index 7346db6933..7e39160557 100644
--- a/crates/ty_python_semantic/resources/mdtest/attributes.md
+++ b/crates/ty_python_semantic/resources/mdtest/attributes.md
@@ -1787,7 +1787,7 @@ date.day = 8
 date.month = 4
 date.year = 2025
 
-# error: [unresolved-attribute] "Can not assign object of `Literal["UTC"]` to attribute `tz` on type `Date` with custom `__setattr__` method."
+# error: [unresolved-attribute] "Can not assign object of type `Literal["UTC"]` to attribute `tz` on type `Date` with custom `__setattr__` method."
 date.tz = "UTC"
 ```
 
diff --git a/crates/ty_python_semantic/src/types/infer.rs b/crates/ty_python_semantic/src/types/infer.rs
index 4b23562d20..b3900380d3 100644
--- a/crates/ty_python_semantic/src/types/infer.rs
+++ b/crates/ty_python_semantic/src/types/infer.rs
@@ -3495,7 +3495,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
                                             self.context.report_lint(&UNRESOLVED_ATTRIBUTE, target)
                                         {
                                             builder.into_diagnostic(format_args!(
-                                                "Can not assign object of `{}` to attribute \
+                                                "Can not assign object of type `{}` to attribute \
                                                  `{attribute}` on type `{}` with \
                                                  custom `__setattr__` method.",
                                                 value_ty.display(db),

From 9a4b85d8456fbd152ae7f7ff149f27ac43e0ea00 Mon Sep 17 00:00:00 2001
From: David Peter <sharkdp@users.noreply.github.com>
Date: Tue, 8 Jul 2025 14:33:46 +0200
Subject: [PATCH 2/2] [ty] Add tests for dataclass fields annotated with
 `Final` (#19202)

## Summary

Adds some tests for dataclass fields that are annotated with `Final`
(see comment
[here](https://github.com/astral-sh/ruff/pull/15768#issuecomment-3044737645)).
Turns out that nothing is needed here, everything already works as
expected (apart from the fact that we can assign to `Final` fields,
which is tracked in https://github.com/astral-sh/ty/issues/158

## Test Plan

New Markdown tests
---
 .../mdtest/dataclasses/dataclasses.md         | 27 +++++++++++++++++++
 .../resources/mdtest/type_qualifiers/final.md |  4 +++
 2 files changed, 31 insertions(+)

diff --git a/crates/ty_python_semantic/resources/mdtest/dataclasses/dataclasses.md b/crates/ty_python_semantic/resources/mdtest/dataclasses/dataclasses.md
index 7ed6ea8962..77a6b22ca0 100644
--- a/crates/ty_python_semantic/resources/mdtest/dataclasses/dataclasses.md
+++ b/crates/ty_python_semantic/resources/mdtest/dataclasses/dataclasses.md
@@ -444,6 +444,33 @@ To do
 
 To do
 
+## `Final` fields
+
+Dataclass fields can be annotated with `Final`, which means that the field cannot be reassigned
+after the instance is created. Fields that are additionally annotated with `ClassVar` are not part
+of the `__init__` signature.
+
+```py
+from dataclasses import dataclass
+from typing import Final, ClassVar
+
+@dataclass
+class C:
+    # a `Final` annotation without a right-hand side is not allowed in normal classes,
+    # but valid for dataclasses. The field will be initialized in the synthesized
+    # `__init__` method
+    instance_variable_no_default: Final[int]
+    instance_variable: Final[int] = 1
+    class_variable1: ClassVar[Final[int]] = 1
+    class_variable2: ClassVar[Final[int]] = 1
+
+reveal_type(C.__init__)  # revealed: (self: C, instance_variable_no_default: int, instance_variable: int = Literal[1]) -> None
+
+c = C(1)
+# TODO: this should be an error
+c.instance_variable = 2
+```
+
 ## Inheritance
 
 ### Normal class inheriting from a dataclass
diff --git a/crates/ty_python_semantic/resources/mdtest/type_qualifiers/final.md b/crates/ty_python_semantic/resources/mdtest/type_qualifiers/final.md
index da1398b1ab..224115f942 100644
--- a/crates/ty_python_semantic/resources/mdtest/type_qualifiers/final.md
+++ b/crates/ty_python_semantic/resources/mdtest/type_qualifiers/final.md
@@ -162,6 +162,10 @@ from typing import Final
 
 # TODO: This should be an error
 NO_RHS: Final
+
+class C:
+    # TODO: This should be an error
+    NO_RHS: Final
 ```
 
 [`typing.final`]: https://docs.python.org/3/library/typing.html#typing.Final