[ty] add special case diagnostic for numbers module

crates/ty_module_resolver/src/module.rs

@@ -334,6 +334,7 @@ pub enum KnownModule {
     UnittestMock,
     Uuid,
     Warnings,
+    Numbers,
 }
 
 impl KnownModule {
@@ -362,6 +363,7 @@ impl KnownModule {
             Self::UnittestMock => "unittest.mock",
             Self::Uuid => "uuid",
             Self::Templatelib => "string.templatelib",
+            Self::Numbers => "numbers",
         }
     }
 

crates/ty_python_semantic/resources/mdtest/assignment/annotations.md

@@ -16,6 +16,16 @@ reveal_type(y)  # revealed: Literal[1]
 x: int = "foo"  # error: [invalid-assignment] "Object of type `Literal["foo"]` is not assignable to `int`"
 ```
 
+## Numbers special case
+
+<!-- snapshot-diagnostics -->
+
+```py
+from numbers import Number
+
+a: Number = 1  # error: [invalid-assignment] "Object of type `Literal[1]` is not assignable to `Number`"
+```
+
 ## Violates previous annotation
 
 ```py

crates/ty_python_semantic/resources/mdtest/snapshots/annotations.md_-_Assignment_with_anno…_-_Numbers_special_case_(457f31497da6a6af).snap

@@ -0,0 +1,38 @@
+---
+source: crates/ty_test/src/lib.rs
+expression: snapshot
+---
+
+---
+mdtest name: annotations.md - Assignment with annotations - Numbers special case
+mdtest path: crates/ty_python_semantic/resources/mdtest/assignment/annotations.md
+---
+
+# Python source files
+
+## mdtest_snippet.py
+
+```
+1 | from numbers import Number
+2 | 
+3 | a: Number = 1  # error: [invalid-assignment] "Object of type `Literal[1]` is not assignable to `Number`"
+```
+
+# Diagnostics
+
+```
+error[invalid-assignment]: Object of type `Literal[1]` is not assignable to `Number`
+ --> src/mdtest_snippet.py:3:4
+  |
+1 | from numbers import Number
+2 |
+3 | a: Number = 1  # error: [invalid-assignment] "Object of type `Literal[1]` is not assignable to `Number`"
+  |    ------   ^ Incompatible value of type `Literal[1]`
+  |    |
+  |    Declared type
+  |
+info: Types from the `numbers` module aren't supported for static type checking
+help: Consider using a protocol instead, such as `typing.SupportsFloat`
+info: rule `invalid-assignment` is enabled by default
+
+```

crates/ty_python_semantic/src/types/diagnostic.rs

@@ -44,7 +44,7 @@ use ruff_python_ast::{self as ast, AnyNodeRef, PythonVersion, StringFlags};
 use ruff_text_size::{Ranged, TextRange};
 use rustc_hash::FxHashSet;
 use std::fmt::{self, Formatter};
-use ty_module_resolver::{Module, ModuleName};
+use ty_module_resolver::{KnownModule, Module, ModuleName, file_to_module};
 
 const RUNTIME_CHECKABLE_DOCS_URL: &str =
     "https://docs.python.org/3/library/typing.html#typing.runtime_checkable";
@@ -2968,6 +2968,26 @@ pub(super) fn report_invalid_assignment<'db>(
         let message = diag.primary_message().to_string();
         diag.set_concise_message(message);
     }
+
+    // special case message
+    if let Type::NominalInstance(target_instance) = target_ty {
+        let db = context.db();
+        let file = target_instance.class(db).class_literal(db).file(db);
+        if let Some(module) = file_to_module(db, file)
+            && module.is_known(db, KnownModule::Numbers)
+        {
+            let is_numeric = [KnownClass::Int, KnownClass::Float, KnownClass::Complex]
+                .iter()
+                .any(|numeric| value_ty.is_subtype_of(db, numeric.to_instance(db)));
+
+            if is_numeric {
+                diag.info(
+                    "Types from the `numbers` module aren't supported for static type checking",
+                );
+                diag.help("Consider using a protocol instead, such as `typing.SupportsFloat`");
+            }
+        }
+    }
 }
 
 pub(super) fn report_invalid_attribute_assignment(