fix(@angular/cli): logic which determines which temp version of the CLI is to be download during ng update

[alan-agius4]

Previously, when using an older version of the Angular CLI, during ng update, we download the temporary latest version to run the update. The ensured that when running that the runner used to run the update contains the latest bug fixes and improvements.

This however, can be problematic in some cases. Such as when there are API breaking changes, when running a relatively old schematic with the latest CLI can cause runtime issues, especially since those schematics were never meant to be executed on a CLI X major versions in the future.

With this change, we improve the logic to determine which version of the Angular CLI should be used to run the update.

Below is a summarization of this.

• When using the --next command line argument, the @next version of the CLI will be used to run the update.
• When updating an @angular/ or @nguniversal/ package, the target version will be used to run the update. Example: ng update @angular/core@12, the update will run on most recent patch version of @angular/cli of that major version @12.2.6.
• When updating an @angular/ or @nguniversal/ and no target version is specified. Example: ng update @angular/core the update will run on most latest version of the @angular/cli.
• When updating a third-party package, the most recent patch version of the installed @angular/cli will be used to run the update. Example if 13.0.0 is installed and 13.1.1 is available on NPM, the latter will be used.

[dgp1130]

When updating an @angular/ or @nguniversal/ and no target version is specified. Example: ng update @angular/core the update will run on most latest version of the @angular/cli.

Does ng update @angular/core go to latest or the next major? If I'm on v10 and run this, it should go to v11 right, since we only allow one major at a time? In that scenario, wouldn't we want to upgrade with the latest patch of the destination major (in this case, @angular/cli@11)?

[alan-agius4]

Does ng update @angular/core go to latest or the next major? If I'm on v10 and run this, it should go to v11 right, since we only allow one major at a time? In that scenario, wouldn't we want to upgrade with the latest patch of the destination major (in this case, @angular/cli@11)?

When no version is specified the update will use the @latest tag. We can improve this but, it might be confusing that updating an angular package will update to the next major version while other packages will update to latest.

[alan-agius4]

Note: once merged, I will create PRs to backport this change to all LTS versions of the CLI.

[dgp1130]

When no version is specified the update will use the @latest tag. We can improve this but, it might be confusing that updating an angular package will update to the next major version while other packages will update to latest.

Hmm, I'm a bit torn here. npm install @angular/core means @angular/core@latest, so I wouldn't want to diverge from that. It would also be weird for @angular/* packages to be special-cased like you mentioned. On the other hand running with the latest CLI means that it needs to support migrating from more than the previous version, which is what we're hoping to avoid.

I just tried this with today's logic to make sure I understood and running ng update @angular/core @angular/cli on a v10 project fails because it tries to update to v13, which isn't allowed (though the error message doesn't actually say that and we should probably be more clear that it tried to update to @latest).

$ ng update @angular/core @angular/cli
Using package manager: 'npm'
Collecting installed dependencies...
Found 29 dependencies.
Fetching dependency metadata from registry...
Updating multiple major versions of '@angular/core' at once is not supported. Please migrate each major version individually.
Run 'ng update @angular/core@11' in your workspace directory to update to latest '11.x' version of '@angular/core'.

For more information about the update process, see https://update.angular.io/?v=10.0-11.0

So I guess the decision of which CLI runner to use doesn't really matter since the update will fail anyways if @latest is not the next major version. Based on that, I'm ok with using the latest CLI runner as you currently have here, but this is maybe something we should look into when we eventually revamp ng update. I would love to see running ng update just go to the next major with no fuss, and this is something we'd have to tackle more comprehensively to make that happen safely.

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