Add loadCompiledTypeAndDependencies() to SchemaParser so that compiled constants…

Add loadCompiledTypeAndDependencies() to SchemaParser so that compiled constants can be cast to static types.

c++/src/capnp/compiler/compiler.h

@@ -162,6 +162,7 @@ public:
   // nodes can be found in the SchemaLoader returned by `getLoader()`.
 
   const SchemaLoader& getLoader() const { return loader; }
+  SchemaLoader& getLoader() { return loader; }
   // Get a SchemaLoader backed by this compiler.  Schema nodes will be lazily constructed as you
   // traverse them using this loader.
 

c++/src/capnp/schema-parser.c++

@@ -196,6 +196,10 @@ SchemaParser::ModuleImpl& SchemaParser::getModuleImpl(kj::Own<SchemaFile>&& file
   return *insertResult.first->second;
 }
 
+SchemaLoader& SchemaParser::getLoader() {
+  return impl->compiler.getLoader();
+}
+
 kj::Maybe<ParsedSchema> ParsedSchema::findNested(kj::StringPtr name) const {
   return parser->impl->compiler.lookup(getProto().getId(), name).map(
       [this](uint64_t childId) {

c++/src/capnp/schema-parser.h

@@ -75,6 +75,12 @@ public:
   // normally.  In this case, the result is a best-effort attempt to compile the schema, but it
   // may be invalid or corrupt, and using it for anything may cause exceptions to be thrown.
 
+  template <typename T>
+  inline void loadCompiledTypeAndDependencies() {
+    // See SchemaLoader::loadCompiledTypeAndDependencies().
+    getLoader().loadCompiledTypeAndDependencies<T>();
+  }
+
 private:
   struct Impl;
   class ModuleImpl;
@@ -82,6 +88,7 @@ private:
   mutable bool hadErrors = false;
 
   ModuleImpl& getModuleImpl(kj::Own<SchemaFile>&& file) const;
+  SchemaLoader& getLoader();
 
   friend class ParsedSchema;
 };