[ty] use Type::Divergent to avoid panic in infinitely-nested-tuple implicit attribute

Author: carljm

Cargo.lock

@@ -143,7 +143,7 @@ regex-automata = { version = "0.4.9" }
 rustc-hash = { version = "2.0.0" }
 rustc-stable-hash = { version = "0.1.2" }
 # When updating salsa, make sure to also update the revision in `fuzz/Cargo.toml`
-salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "a3ffa22cb26756473d56f867aedec3fd907c4dd9", default-features = false, features = [
+salsa = { git = "https://github.com/salsa-rs/salsa.git", rev = "3713cd7eb30821c0c086591832dd6f59f2af7fe7", default-features = false, features = [
     "compact_str",
     "macros",
     "salsa_unstable",

Cargo.toml

@@ -2419,6 +2419,16 @@ reveal_type(Answer.NO.value)  # revealed: Any
 reveal_type(Answer.__members__)  # revealed: MappingProxyType[str, Unknown]
 ```
 
+## Divergent inferred implicit instance attribute types
+
+```py
+class C:
+    def f(self, other: "C"):
+        self.x = (other.x,)
+
+reveal_type((C().x,))  # revealed: tuple[Unknown | Divergent]
+```
+
 ## References
 
 Some of the tests in the *Class and instance variables* section draw inspiration from

crates/ty_python_semantic/resources/mdtest/attributes.md

@@ -762,6 +762,10 @@ impl<'db> Type<'db> {
         Self::Dynamic(DynamicType::Unknown)
     }
 
+    pub(crate) fn divergent(scope: ScopeId<'db>) -> Self {
+        Self::Dynamic(DynamicType::Divergent(DivergentType { scope }))
+    }
+
     pub(crate) fn object(db: &'db dyn Db) -> Self {
         KnownClass::Object.to_instance(db)
     }
@@ -6516,7 +6520,6 @@ impl<'db> Type<'db> {
         }
     }
 
-    #[allow(unused)]
     pub(super) fn has_divergent_type(self, db: &'db dyn Db, div: Type<'db>) -> bool {
         any_over_type(db, self, &|ty| match ty {
             Type::Dynamic(DynamicType::Divergent(_)) => ty == div,