EC
TS4012
TypeScriptERRORNotableDeclarationHIGH confidence

Type parameter 'X' of public method from exported class has or is using priva...

Production Risk

Build will fail; resolve before shipping.

What this means

A declaration emit error (TS4012): Type parameter 'X' of public method from exported class has or is using private name 'X'.. This diagnostic is emitted by the TypeScript compiler when type parameter 'X' of public method from exported class has or is using private name 'X'..

Why it happens
  1. 1Incorrect number or type of generic type arguments
How to reproduce

TypeScript compiler reports TS4012 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS4012
// Type parameter 'X' of public method from exported class has or is using private name 'X'.

expected output

error TS4012: Type parameter 'X' of public method from exported class has or is using private name 'X'.

Fix

Address the TypeScript diagnostic

WHEN When this error is reported by the compiler

Address the TypeScript diagnostic
// Run the TypeScript compiler for details:
npx tsc --noEmit
// Use the TypeScript playground to test your code:
// https://www.typescriptlang.org/play

Why this works

Review the full error message and location; the TypeScript handbook provides guidance on each error category.

Sources
Official documentation ↗

TypeScript Compiler Diagnostics

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