Regression in compiler-cli 10.1.0+: build is 10x times slower

🐞 bug report

Affected Package

The issue is caused by package @angular/compiler-cli@10.1.0

Is this a regression?

Yes, the previous version in which this bug was not present was: @angular/compiler-cli@10.0.14

Description

During an attempt to upgrade our repo to Angular 10.1 we noticed that one of our applications is not building anymore. We have investigated and found that one particular component is now taking too much time to compile (10 minutes and more).

It started on @angular/compiler-cli 10.1.0 With this version an app with only one component takes ~3 minutes to compile. With @angular/compiler-cli 10.0.14 the build takes ~20 seconds to complete.

The issue is reproducible with fullTemplateTypeCheck: true and strictNullChecks: true.

🔬 Minimal Reproduction

https://github.com/x87/ng10bug

Run yarn build and observe build time. Then change strictNullChecks to true in tsconfig.json and re-run yarn build.

🌍 Your Environment

Angular Version:

Angular CLI: 10.1.6
Node: 12.18.2
OS: darwin x64

Angular: 10.1.5
... animations, common, compiler, compiler-cli, core, forms
... language-service, platform-browser, platform-browser-dynamic
... router
Ivy Workspace: Yes

Package                            Version
------------------------------------------------------------
@angular-devkit/architect          0.1001.6
@angular-devkit/build-angular      0.1001.6
@angular-devkit/build-ng-packagr   0.1001.6
@angular-devkit/core               10.1.6
@angular-devkit/schematics         10.1.6
@angular/cli                       10.1.6
@schematics/angular                10.1.6
@schematics/update                 0.1001.6
rxjs                               6.5.5
typescript                         4.0.3

[JoostK]

I reported this in microsoft/TypeScript#41124.

[JoostK]

Hello folks,

TypeScript 4.1.3 was just released which contains a fix for the cache miss issue when computing type information from the control flow graph. Support for TypeScript 4.1 has been added in Angular 11.1, which is slated to be released in January. Preview builds of 11.1 are available on NPM using the next tag, so it is possible to experiment with TS 4.1 today.

I’ll close this issue as we won’t be making changes to Angular to workaround the TS bug (as that would in fact be a performance regression for cases where this bug isn’t hit).