From d30649c66c89883e814b68e51d6f7c5bb46c6d4f Mon Sep 17 00:00:00 2001
From: Glyphack <sh.hooshyari@gmail.com>
Date: Mon, 30 Dec 2024 12:41:47 +0100
Subject: [PATCH] Infer Type::Unknown for a variable with value `...`

---
 .../resources/mdtest/stubs/ellipsis.md                |  4 +++-
 crates/red_knot_python_semantic/src/types/infer.rs    | 11 ++++++++---
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/crates/red_knot_python_semantic/resources/mdtest/stubs/ellipsis.md b/crates/red_knot_python_semantic/resources/mdtest/stubs/ellipsis.md
index 645569427dc3b9..dee9849257ad1a 100644
--- a/crates/red_knot_python_semantic/resources/mdtest/stubs/ellipsis.md
+++ b/crates/red_knot_python_semantic/resources/mdtest/stubs/ellipsis.md
@@ -20,10 +20,12 @@ stub file only.
 ```py path=test.pyi
 y: bytes = ...
 reveal_type(y)  # revealed: bytes
+x = ...
+reveal_type(x)  # revealed: Unknown
 
 class Foo:
     y: int = ...
-    
+
 reveal_type(Foo.y)  # revealed: int
 ```
 
diff --git a/crates/red_knot_python_semantic/src/types/infer.rs b/crates/red_knot_python_semantic/src/types/infer.rs
index 8cb6c0039db4c4..63f1fe231c4acf 100644
--- a/crates/red_knot_python_semantic/src/types/infer.rs
+++ b/crates/red_knot_python_semantic/src/types/infer.rs
@@ -435,6 +435,11 @@ impl<'db> TypeInferenceBuilder<'db> {
         matches!(self.region, InferenceRegion::Deferred(_)) || self.deferred_state.is_deferred()
     }
 
+    /// Are we currently inferring types in a stub file?
+    fn is_stub(&self) -> bool {
+        return self.file().is_stub(self.db().upcast());
+    }
+
     /// Get the already-inferred type of an expression node.
     ///
     /// ## Panics
@@ -1174,7 +1179,7 @@ impl<'db> TypeInferenceBuilder<'db> {
             let inferred_ty = if let Some(default_ty) = default_ty {
                 if default_ty.is_assignable_to(self.db(), declared_ty) {
                     UnionType::from_elements(self.db(), [declared_ty, default_ty])
-                } else if self.file().is_stub(self.db().upcast())
+                } else if self.is_stub()
                     && default
                         .as_ref()
                         .is_some_and(|d| d.is_ellipsis_literal_expr())
@@ -1903,8 +1908,8 @@ impl<'db> TypeInferenceBuilder<'db> {
                 unpacked.get(name_ast_id).unwrap_or(Type::Unknown)
             }
             TargetKind::Name => {
-                if self.file().is_stub(self.db().upcast()) && value.is_ellipsis_literal_expr() {
-                    Type::Any
+                if self.is_stub() && value.is_ellipsis_literal_expr() {
+                    Type::Unknown
                 } else {
                     value_ty
                 }