Revert "[red-knot] Type narrowing for assertions (#17149)" (#17335)

I merged #17149 without checking the ecosystem results, and it still
caused a cycle panic in pybind11. Reverting for now until I fix that, so
we don't lose the ecosystem signal on other PRs.

crates/red_knot_python_semantic/resources/mdtest/narrow/assert.md

@@ -1,53 +0,0 @@
-# Narrowing with assert statements
-
-## `assert` a value `is None` or `is not None`
-
-```py
-def _(x: str | None, y: str | None):
-    assert x is not None
-    reveal_type(x)  # revealed: str
-    assert y is None
-    reveal_type(y)  # revealed: None
-```
-
-## `assert` a value is truthy or falsy
-
-```py
-def _(x: bool, y: bool):
-    assert x
-    reveal_type(x)  # revealed: Literal[True]
-    assert not y
-    reveal_type(y)  # revealed: Literal[False]
-```
-
-## `assert` with `is` and `==` for literals
-
-```py
-from typing import Literal
-
-def _(x: Literal[1, 2, 3], y: Literal[1, 2, 3]):
-    assert x is 2
-    reveal_type(x)  # revealed: Literal[2]
-    assert y == 2
-    reveal_type(y)  # revealed: Literal[1, 2, 3]
-```
-
-## `assert` with `isinstance`
-
-```py
-def _(x: int | str):
-    assert isinstance(x, int)
-    reveal_type(x)  # revealed: int
-```
-
-## `assert` a value `in` a tuple
-
-```py
-from typing import Literal
-
-def _(x: Literal[1, 2, 3], y: Literal[1, 2, 3]):
-    assert x in (1, 2)
-    reveal_type(x)  # revealed: Literal[1, 2]
-    assert y not in (1, 2)
-    reveal_type(y)  # revealed: Literal[3]
-```

crates/red_knot_python_semantic/src/semantic_index/builder.rs

@@ -534,6 +534,7 @@ impl<'db> SemanticIndexBuilder<'db> {
     }
 
     /// Records a visibility constraint by applying it to all live bindings and declarations.
+    #[must_use = "A visibility constraint must always be negated after it is added"]
     fn record_visibility_constraint(
         &mut self,
         predicate: Predicate<'db>,
@@ -1291,17 +1292,6 @@ where
                     );
                 }
             }
-
-            ast::Stmt::Assert(node) => {
-                self.visit_expr(&node.test);
-                let predicate = self.record_expression_narrowing_constraint(&node.test);
-                self.record_visibility_constraint(predicate);
-
-                if let Some(msg) = &node.msg {
-                    self.visit_expr(msg);
-                }
-            }
-
             ast::Stmt::Assign(node) => {
                 debug_assert_eq!(&self.current_assignments, &[]);
 

crates/red_knot_python_semantic/src/types/infer.rs

@@ -3188,7 +3188,7 @@ impl<'db> TypeInferenceBuilder<'db> {
             msg,
         } = assert;
 
-        let test_ty = self.infer_standalone_expression(test);
+        let test_ty = self.infer_expression(test);
 
         if let Err(err) = test_ty.try_bool(self.db()) {
             err.report_diagnostic(&self.context, &**test);