lib,src: fix process.features.cached_builtins when snapshotted

This value is not a constant, in the sense that its value when
running `node_mksnapshot` and when running the default `node` binary
are different.

Author: addaleax

lib/internal/bootstrap/node.js

@@ -197,7 +197,17 @@ ObjectDefineProperty(process, 'features', {
     tls_sni: hasOpenSSL,
     tls_ocsp: hasOpenSSL,
     tls: hasOpenSSL,
-    cached_builtins: config.hasCachedBuiltins,
+  }
+});
+ObjectDefineProperty(process.features, 'cached_builtins', {
+  enumerable: true,
+  configurable: true,
+  get() {
+    return config.hasCachedBuiltins();
+  },
+  set(v) {
+    delete this.cached_builtins;
+    this.cached_builtins = v;
   }
 });
 

src/node_config.cc

@@ -4,17 +4,23 @@
 #include "node_i18n.h"
 #include "node_native_module_env.h"
 #include "node_options.h"
+#include "snapshot_support-inl.h"
 #include "util-inl.h"
 
 namespace node {
 
 using v8::Context;
+using v8::FunctionCallbackInfo;
 using v8::Isolate;
 using v8::Local;
 using v8::Number;
 using v8::Object;
 using v8::Value;
 
+static void HasCachedBuiltins(const FunctionCallbackInfo<Value>& args) {
+  args.GetReturnValue().Set(native_module::has_code_cache);
+}
+
 // The config binding is used to provide an internal view of compile time
 // config options that are required internally by lib/*.js code. This is an
 // alternative to dropping additional properties onto the process object as
@@ -85,10 +91,16 @@ static void Initialize(Local<Object> target,
   READONLY_TRUE_PROPERTY(target, "hasDtrace");
 #endif
 
-  READONLY_PROPERTY(target, "hasCachedBuiltins",
-     v8::Boolean::New(isolate, native_module::has_code_cache));
+  // Make this a method instead of a constant in order for snapshotted builts
+  // to correctly report this.
+  env->SetMethodNoSideEffect(target, "hasCachedBuiltins", HasCachedBuiltins);
 }  // InitConfig
 
+static ExternalReferences external_references {
+  __FILE__,
+  HasCachedBuiltins
+};
+
 }  // namespace node
 
 NODE_MODULE_CONTEXT_AWARE_INTERNAL(config, node::Initialize)