Add inline variable refactor

[Maria Solano (MariaSolOs)]

Fixes#18459

[TypeScript Bot (typescript-bot)]

The TypeScript team hasn't accepted the linked issue #18459. If you can get it accepted, this PR will have a better chance of being reviewed.

[TypeScript Bot (typescript-bot)]

The TypeScript team hasn't accepted the linked issue #18459. If you can get it accepted, this PR will have a better chance of being reviewed.

[TypeScript Bot (typescript-bot)]

The TypeScript team hasn't accepted the linked issue #18459. If you can get it accepted, this PR will have a better chance of being reviewed.

[Matt Bierner (mjbvz)]

Excited to test this out!

[Andrew Branch (andrewbranch)]

I think there are a couple other invalid inlinings to consider.

1. Type queries:

   constBar=classBar{}typeBarConstructor=typeofBar;

   typeof can only take an identifier reference.
2. Merged type/value meanings:

   consta="hello";typea=any;typeT=a;

   There’s one symbol for a with two declarations, so Find All References might return a in type T = a as a reference, even though you wouldn’t want to inline "hello" there. The real case for merging meanings is usually more like

   // Simulate type/value duality of real class declarationsconstSomeClass=mixin(OtherClass);typeSomeClass=typeofSomeClass;

   and in those cases it seems undesirable to inline anyway. I think you can implement a simple rule that says if a symbol has more than one declaration, it can’t be inlined.

[Andrew Branch (andrewbranch)]

This is looking really good! The implementation is impressively small and readable and I like that each test is very focused.

Have you tried to beat this up on some more complicated real-world code? Do that if you haven’t already, and then I would also suggest having one or two kitchen-sink tests that exercise more complex cases with several references and complex expressions (multi-line function expression?)

[Maria Solano (MariaSolOs)]

Andrew Branch (@andrewbranch) I've added a couple more tests with more complex scenarios like call expressions. LMK what you think :)

[Andrew Branch (andrewbranch)]

I still think inlining a multi-line expression would be good to test:

functionComponent(){constonClick/*inline me*/=()=>{console.log("clicked");};return(<buttononClick={onClick}>Dousefulthing</button>);}

[Daniel Rosenwasser (DanielRosenwasser)]

TypeScript Bot (@typescript-bot) pack this
TypeScript Bot (@typescript-bot) user test tsserver
TypeScript Bot (@typescript-bot) test tsserver top100

[Andrew Branch (andrewbranch)]

Looks good to me, nice job 👍

[Daniel Rosenwasser (DanielRosenwasser)]

I SAID

TypeScript Bot (@typescript-bot) pack this
TypeScript Bot (@typescript-bot) user test tsserver
TypeScript Bot (@typescript-bot) test tsserver top100

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the diff-based user code test suite (tsserver) on this PR at 2f97c5c. You can monitor the build here.

Update: The results are in!

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the tarball bundle task on this PR at 2f97c5c. You can monitor the build here.

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the diff-based top-repos suite (tsserver) on this PR at 2f97c5c. You can monitor the build here.

Update: The results are in!

[Daniel Rosenwasser (DanielRosenwasser)]

That's what I thought.

[TypeScript Bot (typescript-bot)]

Hey Daniel Rosenwasser (@DanielRosenwasser), I've packed this into an installable tgz. You can install it for testing by referencing it in your package.json like so:

{
"devDependencies": {
"typescript": "https://typescript.visualstudio.com/cf7ac146-d525-443c-b23c-0d58337efebc/_apis/build/builds/155242/artifacts?artifactName=tgz&fileId=20071FB31E0A3D7DF07B6D5E41FC11EFD71181FE4C4C85CE4B27E7183150EAC902&fileName=/typescript-5.2.0-insiders.20230531.tgz"
}
}

and then running npm install.

---

There is also a playground for this build and an npm module you can use via "typescript": "npm:@typescript-deploys/pr-build@5.2.0-pr-54281-11".;

[TypeScript Bot (typescript-bot)]

Daniel Rosenwasser (@DanielRosenwasser) Here are the results of running the user test suite comparing main and refs/pull/54281/merge:

Everything looks good!

[Daniel Rosenwasser (DanielRosenwasser)]

Here's a fun one I just tried out:

const/**/yadda=()=>yadda;

Error: Debug Failure. False expression: Changes overlap
Verbose Debug Information: {"pos":4,"end":29} and {"pos":24,"end":29}
at c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:166694:15
at mapDefined (c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:2644:22)
at Object.getTextChangesFromChanges (c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:166690:12)
at ChangeTracker.getChanges (c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:166587:35)
at ChangeTracker.with (c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:166071:20)
at Object.getEditsForAction (c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:136427:60)
at Object.getEditsForRefactor (c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:135605:31)
at Object.getEditsForRefactor2 [as getEditsForRefactor] (c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:142982:32)
at IpcIOSession.getEditsForRefactor (c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:182282:49)
at getEditsForRefactor (c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:180538:43)
at c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:182666:69
at IpcIOSession.executeWithRequestId (c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:182658:14)
at IpcIOSession.executeCommand (c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:182666:29)
at IpcIOSession.onMessage (c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:182708:51)
at process.<anonymous> (c:/Users/Daniel/workspace/node_modules/typescript/lib/tsserver.js:184288:14)
at process.emit (node:events:513:28)
at emit (node:internal/child_process:958:14)
at process.processTicksAndRejections (node:internal/process/task_queues:84:21)

[Maria Solano (MariaSolOs)]

Also, I noticed that if I request an inline at the following position

let/**/asdasd=42;letqwerty=asdasd;

the refactoring is made available, but not elsewhere on the let (e.g. l/**/et asdasd = ...).

I feel like it should either work solely on:

1. The variable name
2. The variable name or the variable statement keyword
3. The entire variable statement

Daniel Rosenwasser (@DanielRosenwasser) I believe we should stick with option 1, since there would be an ambiguity about what to inline in cases like let x = 0, y = 1 with the other 2 options.

However, if I change this bit to:

if(isIdentifier(token)&&isInitializedVariable(parent)&&isVariableDeclarationInVariableStatement(parent)){

The refactor is still available in let/**/ foo = 0;, since I believe that's leading trivia that belongs to the identifier node. I think this should be fine...?

[Daniel Rosenwasser (DanielRosenwasser)]

TypeScript Bot (@typescript-bot) pack this

[TypeScript Bot (typescript-bot)]

Heya Daniel Rosenwasser (@DanielRosenwasser), I've started to run the tarball bundle task on this PR at 67a5880. You can monitor the build here.

[TypeScript Bot (typescript-bot)]

Hey Daniel Rosenwasser (@DanielRosenwasser), I've packed this into an installable tgz. You can install it for testing by referencing it in your package.json like so:

{
"devDependencies": {
"typescript": "https://typescript.visualstudio.com/cf7ac146-d525-443c-b23c-0d58337efebc/_apis/build/builds/155454/artifacts?artifactName=tgz&fileId=6087B18552E765F2B38E8662F37137B2540138A75BDE31954CDB44014CC8C60C02&fileName=/typescript-5.2.0-insiders.20230612.tgz"
}
}

and then running npm install.

---

There is also a playground for this build and an npm module you can use via "typescript": "npm:@typescript-deploys/pr-build@5.2.0-pr-54281-25".;

[Michael Borislav (awerlogus)]

Inlining variable data changes runtime behaviour. Is it bug or design limitation?

constdata=newMap()constgetter=()=>data.get('foo')data.set('foo','bar')console.log(getter())