fullTemplateCheck not recognizing unary (+) operator and incorrect handing of (==) in template

🐞 bug report

Description

I’m finally getting around to using angularCompilerOptions and have started to use fullTemplateCheck. It seems as if while checking the templates, there is a failure to see the + unary operator in front of the hours variable (hours is a string). The + turns the string into a number so I believe this is an incorrect error, and therefore a bug?

Also it seems like fullTemplateCheck is incorrectly handing ==, as it incorrectly states that the result will always return false in the second code snippet below.

🔥 Exception or Error

Unary:

error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number', 'bigint' or an enum type.
<div (click)="formatHours(+hours + 1)">

Doulble Equals:

error TS2367: This condition will always return 'false' since the types 'string' and 'number' have no overlap.
<div [ngClass]="{'disabled': displayHours == 23}">

Environment

Angular Version:

Angular CLI: 9.0.4
Node: 10.16.1
OS: linux x64

Angular: 9.0.4
... animations, cli, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router
Ivy Workspace: Yes

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.900.4
@angular-devkit/build-angular     0.900.4
@angular-devkit/build-optimizer   0.900.4
@angular-devkit/build-webpack     0.900.4
@angular-devkit/core              9.0.4
@angular-devkit/schematics        9.0.4
@angular/cdk                      9.1.0
@angular/material                 9.1.0
@ngtools/webpack                  9.0.4
@schematics/angular               9.0.4
@schematics/update                0.900.4
rxjs                              6.5.4
typescript                        3.7.5
webpack                           4.41.2

[JoostK]

I can sympathize with TypeScript’s choice here. Very unexpected things can happen with these sorts of comparisons. For instance, 1000 == '1.e3' is true in JavaScript 😉 You’d be better off by converting the number to a string instead, avoiding the problem.

I edited my original comment for the unary operator with an alternative workaround to a method on the class. Your choice on which you choose.

I don’t think this issue will be fixed soon to be honest, but let’s hope it won’t be 3 years 😉 The occurrence of the issue from 2017 is less common.

[serbboy23]

My initial thought with the == was to use a + in front of the displayHours variable so that two numbers are being compared, however that brings me back to the main issue at hand here.