bootstrap: improve snapshot unsupported builtin warnings

- Only emit warning when the snapshot is built. In general built-ins loaded after the snapshot is built should work as usual. - Clarify what the warning means PR-URL: #50944 Reviewed-By: Vinícius Lourenço Claro Cardoso <[email protected]> Reviewed-By: Antoine du Hamel <[email protected]> Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: James M Snell <[email protected]>

Author: joyeecheung

lib/internal/main/mksnapshot.js

@@ -19,7 +19,7 @@ const{
 const{ isExperimentalSeaWarningNeeded }=internalBinding('sea');
 
 const{ emitExperimentalWarning }=require('internal/util');
-
+const{ emitWarningSync }=require('internal/process/warning');
 const{
  getOptionValue,
 }=require('internal/options');
@@ -29,6 +29,7 @@ const{
 namespace: {
  addSerializeCallback,
  addDeserializeCallback,
+ isBuildingSnapshot,
 },
 }=require('internal/v8/startup_snapshot');
 
@@ -119,10 +120,18 @@ function requireForUserSnapshot(id){
 err.code='MODULE_NOT_FOUND';
 throwerr;
 }
-if(!supportedInUserSnapshot(normalizedId)){
+if(isBuildingSnapshot()&&!supportedInUserSnapshot(normalizedId)){
 if(!warnedModules.has(normalizedId)){
-process.emitWarning(
-`built-in module ${id} is not yet supported in user snapshots`);
+// Emit the warning synchronously in case we don't get to process
+// the tick and print it before the unsupported built-in causes a
+// crash.
+emitWarningSync(
+`It's not yet fully verified whether built-in module "${id}" `+
+'works in user snapshot builder scripts.\n'+
+'It may still work in some cases, but in other cases certain '+
+'run-time states may be out-of-sync after snapshot deserialization.\n'+
+'To request support for the module, use the Node.js issue tracker: '+
+'https://github.com/nodejs/node/issues');
 warnedModules.add(normalizedId);
 }
 }