Add some basic escape analysis errors for return &x

src/entity.cpp

@@ -229,6 +229,7 @@ struct Entity {
 			CommentGroup *comment;
 			bool       is_foreign;
 			bool       is_export;
+			bool       is_global;
 		} Variable;
 		struct {
 			Type * type_parameter_specialization;
@@ -480,3 +481,25 @@ gb_internal Entity *strip_entity_wrapping(Ast *expr) {
 	Entity *e = entity_from_expr(expr);
 	return strip_entity_wrapping(e);
 }
+
+
+gb_internal bool is_entity_local_variable(Entity *e) {
+	if (e == nullptr) {
+		return false;
+	}
+	if (e->kind != Entity_Variable) {
+		return false;
+	}
+	if (e->Variable.is_global) {
+		return false;
+	}
+	if (e->scope == nullptr) {
+		return true;
+	}
+	if (e->flags & (EntityFlag_ForValue|EntityFlag_SwitchValue)) {
+		return false;
+	}
+
+	return ((e->scope->flags &~ ScopeFlag_ContextDefined) == 0) ||
+	       (e->scope->flags & ScopeFlag_Proc) != 0;
+}