Update typescript to the latest version 🚀

[greenkeeper]

Version 2.5.2 of typescript just got published.

Dependency	typescript
Current Version	2.4.2
Type	devDependency

The version 2.5.2 is not covered by your current version range.

Without accepting this pull request your project will work just like it did before. There might be a bunch of new features, fixes and perf improvements that the maintainers worked on for you though.

I recommend you look into these changes and try to get onto the latest version of typescript.
Given that you have a decent test suite, a passing build is a strong indicator that you can take advantage of these changes by merging the proposed change into your project. Otherwise this branch is a great starting point for you to work on the update.

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Release Notes

TypeScript 2.5

For release notes, check out the release announcement

For new features, check out the What's new in TypeScript 2.5.

For the complete list of fixed issues, check out the issues fixed in TypeScript 2.5 RC and after TypeScript 2.5 RC.

Download:

• npm
• Visual Studio 2015 plugin
• Visual Studio 2017 (Select new version in Tools/Options)
• NuGet package

Special thanks to all contributors to this release:

• Anders Hejlsberg
• Andrew Casey
• Andy Hanson
• Arthur Ozga
• Basarat Ali Syed
• Benjamin Lichtman
• Daniel Rosenwasser
• Francois Wouts
• Jan Melcher
• Kanchalai Tanglertsampan
• Klaus Meinhardt
• Kārlis Gaņģis
• Matt Mitchell
• Mine Starks
• Mohamed Hegazy
• Nathan Shively-Sanders
• Paul van Brenk
• Ron Buckton
• Ryan Cavanaugh
• Sheetal Nandi
• Tingan Ho
• Tycho Grouwstra
• Wesley Wigham

Commits

The new version differs by 652 commits ahead by 652, behind by 75.

• 171c664 Update LKG
• 20da159 Merge pull request #18127 from RyanCavanaugh/port18120_release25
• 6425ea2 Don't crash when a JS file appears in an inferred context
• 6ffe829 Update LKG
• 15a0d3f Update version
• 2a2773f Update LKG
• 187a21c Fix crash in name resolution with custom transforms and emitDecoratorMetadata
• 62678cd Don't try to extract import to a method: simpler fix (#18054)
• 3644771 Test for action description of code actions, and simplify description for extracting method to file (#18030) (#18044)
• a39ae1f Fix crash when attempting to merge an import with a local declaration (#18032) (#18034)
• 350c9f6 Call dynamic import transform on expression used by export equal statement (#18028) (#18033)
• 0851f69 Added additional test
• 01b7df6 Switch to arrow for ts class wrapper IIFE
• 9bb1915 PR feedback
• ec8f5cf Follow symbol through commonjs require for inferred class type

There are 250 commits in total.

See the full diff

Not sure how things should work exactly?

There is a collection of frequently asked questions and of course you may always ask my humans.

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Your Greenkeeper Bot 🌴

[ikatyang]

@tycho01 It seems the Omit will cause dissoc issues in TS v2.5 (for object with non-explicit keys), I have no idea how to tackle it, should we just skip it? as it works well before 2.5 and now it looks like needs some type-level if..else to determine if it has index signature or not.

R_dissoc(string_property, object)

- "Pick<object, any>"
+ "Pick<object, never>"

R_dissoc(string_property)(object)

- "Pick<object, any>"
+ "Pick<object, never>"

Inferred

  R_dissoc(string_property, string_number_record)

to be

  Pick<Record<string, number>, never>

Inferred

  R_dissoc(string_property)(string_number_record)

to be

  Pick<Record<string, number>, never>

[KiaraGrouwstra]

@ikatyang: Right. Up to you, I'm cool with delaying either Omit or the upgrade.

needs some type-level if..else to determine if it has index signature or not

So unfortunately that's not possible on TS nightlies yet. It's possible to access a string index T[string], but if it's not (guaranteed to be) there then doing that just results in a type error.

A solution I could think of there is type pattern matching, i.e. that 6606. My PR there is still in progress, but the pattern matching also still suffers from an additional issue... Not helping much right now yet I fear.

You could try reporting the issue as a regression actually.

[ikatyang]

I'd like to delay the upgrade, but there are some bug fixes required by DT tests in TS 2.5. 😰

For the regression issue, I'm not sure if it is a regression since I did not understand its implementation actually, maybe it's caused by the & { [x: string]: never } in Diff?

[KiaraGrouwstra]

I think things got stricter and it no longer considers object types to have a string index unless they actually do.
I believe before it would accept others as well, implicitly yielding the union of the object's values if you tried accessing the string index.
I'm not sure which version/PR this happened in though, I just noticed the change in behavior like you did.