apple/pkl · error

redundantHiddenModifier

redundantHiddenModifier

Error message

redundantHiddenModifier

What it means

`local` members are already confined to their enclosing object and invisible outside it, so adding `hidden` is meaningless. AstBuilder rejects the combination `local hidden` with `redundantHiddenModifier`, pointing at the HIDDEN modifier (AstBuilder.java:3016).

Source

Thrown at pkl-core/src/main/java/org/pkl/core/ast/builder/AstBuilder.java:3016

        throw exceptionBuilder()
            .evalError(errorMessage, ctx.getValue().name().toLowerCase(Locale.ROOT))
            .withSourceSection(createSourceSection(ctx))
            .build();
      }
      result += modifier;
    }

    // flag modifier combinations that are never valid right away

    if (VmModifier.isExternal(result) && !ModuleKeys.isStdLibModule(moduleKey)) {
      throw exceptionBuilder()
          .evalError("cannotDefineExternalMember")
          .withSourceSection(createSourceSection(modifiers, ModifierValue.EXTERNAL))
          .build();
    }

    if (VmModifier.isLocal(result) && VmModifier.isHidden(result)) {
      throw exceptionBuilder()
          .evalError("redundantHiddenModifier")
          .withSourceSection(createSourceSection(modifiers, ModifierValue.HIDDEN))
          .build();
    }

    if (VmModifier.isLocal(result) && VmModifier.isFixed(result)) {
      throw exceptionBuilder()
          .evalError("redundantFixedModifier")
          .withSourceSection(createSourceSection(modifiers, ModifierValue.FIXED))
          .build();
    }

    if (VmModifier.isAbstract(result) && VmModifier.isOpen(result)) {
      throw exceptionBuilder()
          .evalError("redundantOpenModifier")
          .withSourceSection(createSourceSection(modifiers, ModifierValue.OPEN))
          .build();
    }

View on GitHub (pinned to f3efcbfc9b)

Solutions

1. Remove the redundant `hidden` modifier, keep `local`.
2. If the member should be visible but not rendered in output, drop `local` and keep `hidden`.

Example fix

// before
local hidden foo = 1
// after
local foo = 1

if (/local\s+hidden\b/.test(pklSource)) {
  throw new Error("`hidden` is redundant on `local` members; remove one");
}

When it happens

Trigger: Declaring `local hidden foo = ...` in a module, class, or object body.

Common situations: Piling modifiers on for safety without knowing their semantics; adding `hidden` after converting a property to `local`.

Understand the failure class

Background: Conflicting config options: "cannot be used together" — configuration validation errors across open-source libraries — this error's family across 162 libraries.

Related errors

• redundantFixedModifier
• moduleMethodMustBeLocal
• invalidObjectMemberModifier
• redundantOpenModifier
• Cannot parse `%s` as number.

AI-assisted analysis of apple/pkl@f3efcbfc9b (2026-09-08). Data as JSON: /api/errors/83581597ed6b82f0. Report an issue: GitHub.