Support for Typescript 4.x

[lschierer]

Describe the feature

I am told that the reason that AWS CDK depends on Typescript 3.9 is beacuse of jsii in #18743, I am now stuck in a situation where cdk cannot use typescript above 3.9 and tsc cannot use typescript below 4.2 (due to @types issue 60310). While that might get reverted eventually, it points to the long term unsustainable nature of requiring a version of a key library that is both an entire major version behind and 7 overall releases behind.

Use Case

Compatibility: I cannot run cdk after running npm up at all because @types/prettier automatically upgrades unless manually pinned (which I did not know to do), nor can I initialize a new cdk workspace with typescript because the install grabs the latest version of @types/prettier which won't work with the required version of typescript.

Proposed Solution

Upgrade the supported version of typescript.

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

CDK version used

2.28.1 (build d035432)

Environment details (OS name and version, etc.)

Ubuntu 20 LTS with node 16 from https://nodesource.com/, but also tested and verified on OSX 12.2 with node from homebrew

[webratz]

There was an attempt with #1940 but it never was merged due to potential breaking changes.

I really hope it would be done anyway at some time as this is making things tricky very often, and the situation won't improve

[RichiCoder1]

There's a proposal out with aws/aws-cdk-rfcs#373 to fix this, but I'm not sure what it's present status is.

[RomainMuller]

@RichiCoder1 you're correct, this is the current plan. I've investigated doing a "bring your own typescript" with adapters but it turns out to be nearly impossible to do without creating a maintenance nightmare.

The RFC still stands as the best plan I have so far, and I would like to implement that sooner rather than later (but so far received very little traction/interest).

[ansgarm]

Given that DefinitelyTyped just dropped support for TS versions <4.x (as they only support TS versions that are less than two years old), this issue seems to become a bit more pressing 😅
Related: DefinitelyTyped/DefinitelyTyped#64262

[RomainMuller]

We are actively working on RFC 373, and plan to have preview releases out as soon as possible.

[RichiCoder1]

That's awesome! I'm sure the team is aware, but hopefully some of the insight from that work can help with the now impending TS 5 release coming out this quarter. I don't think there's an urgency, but still!

[arnulfojr]

So I guess with jsii@^5 typescript 5 is now supported and this issue is resolved?

CDK ^2.72 uses migrated to use jsii@~5 and ts 5
aws/aws-cdk@6d581d7
https://aws.github.io/jsii/compiler-and-rosetta-maintenance/

[github-actions]

This issue is now closed. Comments on closed issues are hard for our team to see.
If you need more assistance, please open a new issue that references this one.

[mrgrain]

So I guess with jsii@^5 typescript 5 is now supported and this issue is resolved?

CDK ^2.72 uses migrated to use jsii@~5 and ts 5 aws/aws-cdk@6d581d7 https://aws.github.io/jsii/compiler-and-rosetta-maintenance/

Yes, modern TS is fully supported now.