Make Namespace PartialEq. Add missing filter to optimize.

By making `Namespace` `PartialEq`, we're able to re-add the original
filter to the `optimize` pass that ensures we don't unnecessarily
re-compile constants for the current module.

sway-core/src/optimize.rs

@@ -123,7 +123,10 @@ fn compile_constants(
         }
     }
 
-    for ns in namespace.get_all_imported_modules() {
+    for ns in namespace
+        .get_all_imported_modules()
+        .filter(|&ns| ns == namespace)
+    {
         compile_constants(context, module, ns, true)?;
     }
 

sway-core/src/semantic_analysis/namespace.rs

@@ -27,7 +27,7 @@ type UseAliases = im::HashMap<String, Ident>;
 /// importing.
 ///
 /// The namespace is constructed during type checking.
-#[derive(Clone, Debug, Default)]
+#[derive(Clone, Debug, Default, PartialEq)]
 pub struct Namespace {
     // This is a BTreeMap because we rely on its ordering being consistent. See
     // [Namespace::get_all_declared_symbols] -- we need that iterator to have a deterministic
@@ -855,7 +855,7 @@ impl Namespace {
 type TraitMapInner = im::Vector<((TraitName, TypeInfo), TraitMethods)>;
 type TraitMethods = im::HashMap<String, TypedFunctionDeclaration>;
 
-#[derive(Clone, Debug, Default)]
+#[derive(Clone, Debug, Default, PartialEq)]
 pub(crate) struct TraitMap {
     trait_map: TraitMapInner,
 }