False positive Error - TS6133 error (declared but its value is never read) report.

[somzJosf]

tsc --version
Version 2.6.1 , Also tried on 2.7.0-dev.20171102

class SomeClass {
	private manualPrice: number = 0;

	public someMethod() {
		this.manualPrice = 10; 
	}
}

and then compile file: tsc --noUnusedLocals

Expected behavior: No erros

Actual behavior: error TS6133: 'manualPriceTotal' is declared but its value is never read.

[ajafff]

Since you never use the value of this property anywhere, I'd say the error is expected.

[mhegazy]

please see https://github.com/Microsoft/TypeScript/wiki/Breaking-Changes#write-only-references-are-unused

[somzJosf]

@mhegazy: Thanks for the doc.
In my case, I have been using this in my template. But, even it was marked as private, I don't know how the template was getting its value. Anyway, that property is intended to be public. I fixed it in my code. And the error is now gone. Thanks.

[matjaz]

Using private vars in .vue files in template reported as unused. Changing to protected solved the issue.
Typescript does not know the context of .vue and templates, so it makes a perfect sense to mark as unused. OTOH we don't want readonly template variables to be publicly writable.

[mentatxx]

It causes a lot of problems in Angular
I do

import { Component, OnInit } from '@angular/core';

export class AppComponent implements OnInit, OnDestroy {

And OnInit is reported as "is declared but its value is never read."

[RyanCavanaugh]

@mentatxx can you provide a self-contained repro? I can't reproduce the problem

[mariohmol]

Having same issue here, have a variable that is declared, populated on ngOnInit and is used on the template.. but TS can't see this using in the template.. in my case i have it changed in tsconfig.conf like "noUnusedLocals": true,

[agnislav]

The same issue with angulal specs - declaring a spy leads to the same error.

[tho-graf]

Hi there,
I found a minimal repro. But it only occours in the watch-mode. If you checkout the repo and run tsc --noEmit -w -p . you will get the error.

https://github.com/thomaskempel/tsc2.7.1-bug