red-knot: Add not unary operator for integer literals

crates/red_knot_python_semantic/src/types/infer.rs

@@ -2212,6 +2212,10 @@ impl<'db> TypeInferenceBuilder<'db> {
         match (op, self.infer_expression(operand)) {
             (UnaryOp::USub, Type::IntLiteral(value)) => Type::IntLiteral(-value),
             (UnaryOp::Not, Type::BooleanLiteral(value)) => Type::BooleanLiteral(!value),
+            (UnaryOp::Not, Type::IntLiteral(value)) => match value {
+                0 => Type::BooleanLiteral(true),
+                _ => Type::BooleanLiteral(false),
+            },
             _ => Type::Unknown, // TODO other unary op types
         }
     }
@@ -3165,6 +3169,31 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn not_integer_literal() -> anyhow::Result<()> {
+        let mut db = setup_db();
+
+        db.write_file(
+            "src/a.py",
+            r#"
+            a = not 1
+            b = not 1234567890987654321
+            e = not 0
+            x = not -1
+            y = not -1234567890987654321
+            z = not --987
+            "#,
+        )?;
+        assert_public_ty(&db, "src/a.py", "a", "Literal[False]");
+        assert_public_ty(&db, "src/a.py", "b", "Literal[False]");
+        assert_public_ty(&db, "src/a.py", "e", "Literal[True]");
+        assert_public_ty(&db, "src/a.py", "x", "Literal[False]");
+        assert_public_ty(&db, "src/a.py", "y", "Literal[False]");
+        assert_public_ty(&db, "src/a.py", "z", "Literal[False]");
+
+        Ok(())
+    }
+
     #[test]
     fn string_type() -> anyhow::Result<()> {
         let mut db = setup_db();