Why export circular of less.importManager.less.importManager.less....? Bug or by Design?

[shiftj18]

To reproduce:

// less code here
require('less');

Current behavior:

Expected behavior:

No circular.

Environment information:

• less version: ^4
• nodejs version: node 16
• operating system: macos

[puckowski]

I tested Less.js 4.2.0 on Node 18 and run into no issues requiring and using less.

That said, removing the property less from import manager seems to have no adverse effect. All tests pass with this particular circular reference removed.

I am sure that is not the only circular reference in Less 4.2.0.

[shiftj18]

OK, thanks. There are indeed many loops in webpack configs.

I change the implement of print JSON.stringify(webpackConfigs) to solve this question replace with node:util inspect().

The old way is use the parameter replacer of the JSON.stringify() to solve circular data. Which cause Node16 crash when the webpack configs has many circular reference and too big. refer to https://stackoverflow.com/a/11616993.

JSON.safeStringify = (obj, indent = 2) => {
  let cache = [];
  const retVal = JSON.stringify(
    obj,
    (key, value) =>
      typeof value === "object" && value !== null
        ? cache.includes(value)
          ? undefined // Duplicate reference found, discard key
          : cache.push(value) && value // Store value in our collection
        : value,
    indent
  );
  cache = null;
  return retVal;
};

// Example:
console.log('options', JSON.safeStringify(options))

#
# Fatal error in , line 0
# Check failed: has_pending_exception().
#
#
#
#FailureMessage Object: 0x16f995318
 1: 0x100583d20 node::NodePlatform::GetStackTracePrinter()::$_3::__invoke() [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
 2: 0x10132b414 V8_Fatal(char const*, ...) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
 3: 0x1007953a8 v8::internal::Isolate::is_catchable_by_wasm(v8::internal::Object) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
 4: 0x100e25dc0 Builtins_CEntry_Return1_DontSaveFPRegs_ArgvOnStack_BuiltinExit [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
 5: 0x100db9898 Builtins_InterpreterEntryTrampoline [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
 6: 0x100db9898 Builtins_InterpreterEntryTrampoline [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
 7: 0x100db9898 Builtins_InterpreterEntryTrampoline [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
 8: 0x100deb06c Builtins_GeneratorPrototypeNext [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
 9: 0x105a13b78 
10: 0x100e6dd38 Builtins_PromiseFulfillReactionJob [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
11: 0x100ddb274 Builtins_RunMicrotasks [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
12: 0x100db7564 Builtins_JSRunMicrotasksEntry [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
13: 0x100784570 v8::internal::(anonymous namespace)::Invoke(v8::internal::Isolate*, v8::internal::(anonymous namespace)::InvokeParams const&) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
14: 0x1007849a4 v8::internal::(anonymous namespace)::InvokeWithTryCatch(v8::internal::Isolate*, v8::internal::(anonymous namespace)::InvokeParams const&) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
15: 0x100784a90 v8::internal::Execution::TryRunMicrotasks(v8::internal::Isolate*, v8::internal::MicrotaskQueue*, v8::internal::MaybeHandle<v8::internal::Object>*) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
16: 0x1007a749c v8::internal::MicrotaskQueue::RunMicrotasks(v8::internal::Isolate*) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
17: 0x1007a7d30 v8::internal::MicrotaskQueue::PerformCheckpoint(v8::Isolate*) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
18: 0x1006e164c v8::internal::FunctionCallbackArguments::Call(v8::internal::CallHandlerInfo) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
19: 0x1006e1144 v8::internal::MaybeHandle<v8::internal::Object> v8::internal::(anonymous namespace)::HandleApiCallHelper<false>(v8::internal::Isolate*, v8::internal::Handle<v8::internal::HeapObject>, v8::internal::Handle<v8::internal::HeapObject>, v8::internal::Handle<v8::internal::FunctionTemplateInfo>, v8::internal::Handle<v8::internal::Object>, v8::internal::BuiltinArguments) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
20: 0x1006e0a00 v8::internal::Builtin_HandleApiCall(int, unsigned long*, v8::internal::Isolate*) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
21: 0x100e25d4c Builtins_CEntry_Return1_DontSaveFPRegs_ArgvOnStack_BuiltinExit [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
22: 0x1052cc178 
23: 0x100db768c Builtins_JSEntryTrampoline [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
24: 0x100db7324 Builtins_JSEntry [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
25: 0x1007845a8 v8::internal::(anonymous namespace)::Invoke(v8::internal::Isolate*, v8::internal::(anonymous namespace)::InvokeParams const&) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
26: 0x100783c44 v8::internal::Execution::Call(v8::internal::Isolate*, v8::internal::Handle<v8::internal::Object>, v8::internal::Handle<v8::internal::Object>, int, v8::internal::Handle<v8::internal::Object>*) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
27: 0x1006905f4 v8::Function::Call(v8::Local<v8::Context>, v8::Local<v8::Value>, int, v8::Local<v8::Value>*) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
28: 0x100469edc node::InternalCallbackScope::Close() [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
29: 0x1004697c4 node::InternalCallbackScope::~InternalCallbackScope() [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
30: 0x1004ce684 node::Environment::RunTimers(uv_timer_s*) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
31: 0x100d98718 uv__run_timers [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
32: 0x100d9b74c uv_run [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
33: 0x10046acb8 node::SpinEventLoop(node::Environment*) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
34: 0x10055dadc node::NodeMainInstance::Run(int*, node::Environment*) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
35: 0x10055d7a8 node::NodeMainInstance::Run(node::EnvSerializeInfo const*) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
36: 0x1004f76bc node::Start(int, char**) [/Users/shiftj/.nvm/versions/node/v16.15.0/bin/node]
37: 0x10512108c 

[matthew-dean]

The short answer is that Less was created before many modern import conventions. I think the other reason is that the importManager is passed to plugins, but then less was added so that it can be used as well? Not sure.