Enable attribute lookups via semantic model (#5536)

## Summary

This PR enables us to resolve attribute accesses within files, at least
for static and class methods. For example, we can now detect that this
is a function access (and avoid a false-positive):

```python
class Class:
    @staticmethod
    def error():
        return ValueError("Something")


# OK
raise Class.error()
```

Closes #5487.

Closes #5416.

crates/ruff_python_semantic/src/binding.rs

@@ -126,11 +126,11 @@ impl<'a> Binding<'a> {
         }
         matches!(
             existing.kind,
-            BindingKind::ClassDefinition
-                | BindingKind::FunctionDefinition
-                | BindingKind::Import(..)
-                | BindingKind::FromImport(..)
-                | BindingKind::SubmoduleImport(..)
+            BindingKind::ClassDefinition(_)
+                | BindingKind::FunctionDefinition(_)
+                | BindingKind::Import(_)
+                | BindingKind::FromImport(_)
+                | BindingKind::SubmoduleImport(_)
         )
     }
 
@@ -372,14 +372,14 @@ pub enum BindingKind<'a> {
     /// class Foo:
     ///     ...
     /// ```
-    ClassDefinition,
+    ClassDefinition(ScopeId),
 
     /// A binding for a function, like `foo` in:
     /// ```python
     /// def foo():
     ///     ...
     /// ```
-    FunctionDefinition,
+    FunctionDefinition(ScopeId),
 
     /// A binding for an `__all__` export, like `__all__` in:
     /// ```python

crates/ruff_python_semantic/src/model.rs

@@ -414,7 +414,7 @@ impl<'a> SemanticModel<'a> {
 
     /// Lookup a symbol in the current scope. This is a carbon copy of [`Self::resolve_read`], but
     /// doesn't add any read references to the resolved symbol.
-    pub fn lookup(&mut self, symbol: &str) -> Option<BindingId> {
+    pub fn lookup_symbol(&self, symbol: &str) -> Option<BindingId> {
         if self.in_forward_reference() {
             if let Some(binding_id) = self.scopes.global().get(symbol) {
                 if !self.bindings[binding_id].is_unbound() {
@@ -456,6 +456,32 @@ impl<'a> SemanticModel<'a> {
         None
     }
 
+    /// Lookup a qualified attribute in the current scope.
+    ///
+    /// For example, given `["Class", "method"`], resolve the `BindingKind::ClassDefinition`
+    /// associated with `Class`, then the `BindingKind::FunctionDefinition` associated with
+    /// `Class#method`.
+    pub fn lookup_attribute(&'a self, value: &'a Expr) -> Option<BindingId> {
+        let call_path = collect_call_path(value)?;
+
+        // Find the symbol in the current scope.
+        let (symbol, attribute) = call_path.split_first()?;
+        let mut binding_id = self.lookup_symbol(symbol)?;
+
+        // Recursively resolve class attributes, e.g., `foo.bar.baz` in.
+        let mut tail = attribute;
+        while let Some((symbol, rest)) = tail.split_first() {
+            // Find the next symbol in the class scope.
+            let BindingKind::ClassDefinition(scope_id) = self.binding(binding_id).kind else {
+                return None;
+            };
+            binding_id = self.scopes[scope_id].get(symbol)?;
+            tail = rest;
+        }
+
+        Some(binding_id)
+    }
+
     /// Given a `BindingId`, return the `BindingId` of the submodule import that it aliases.
     fn resolve_submodule(
         &self,