Update typescript to 4.8

[JLHwung]

Q	A
Any Dependency Changes?	Bump TS to 4.8 and fix new typing errors
License	MIT

Also removed babel-parser's tsconfig now that we have converted the parser to TS.

[JLHwung]

T is constrained to string so that Array.isArray(el) can effectively differentiate between ReadonlyDeepArray<T> and T.

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/52822/

There is the OOM error you mentioned :/

[liuxingbaoyu]

This should be a new bug, not even enabling strictNullCheck. :)

[liuxingbaoyu]

ts4.7

PS F:\babel> yarn tsc --extendedDiagnostics --incremental false
Files:                          714
Lines of Library:             27958
Lines of Definitions:         48613
Lines of TypeScript:         109737
Lines of JavaScript:              0
Lines of JSON:                 4198
Lines of Other:                   0
Nodes of Library:            119371
Nodes of Definitions:        127849
Nodes of TypeScript:         416262
Nodes of JavaScript:              0
Nodes of JSON:                11813
Nodes of Other:                   0
Identifiers:                 230675
Symbols:                     959380
Types:                       380554
Instantiations:            42135598
Memory used:               1117681K
Assignability cache size:    262472
Identity cache size:          16941
Subtype cache size:          100724
Strict subtype cache size:     8524
I/O Read time:                0.08s
Parse time:                   0.75s
ResolveModule time:           0.18s
ResolveTypeReference time:    0.01s
Program time:                 1.11s
Bind time:                    0.42s
Check time:                  19.77s
transformTime time:           1.32s
Source Map time:              0.05s
commentTime time:             0.08s
I/O Write time:               0.26s
printTime time:               2.18s
Emit time:                    2.19s
Total time:                  23.49s

ts4.8

PS F:\babel> yarn tsc --extendedDiagnostics --incremental false
Files:                          715
Lines of Library:             28146
Lines of Definitions:         48613
Lines of TypeScript:         109741
Lines of JavaScript:              0
Lines of JSON:                 4198
Lines of Other:                   0
Nodes of Library:            118224
Nodes of Definitions:        126241
Nodes of TypeScript:         413313
Nodes of JavaScript:              0
Nodes of JSON:                11813
Nodes of Other:                   0
Identifiers:                 230557
Symbols:                    2992041
Types:                      1556880
Instantiations:            42130595
Memory used:               3987979K
Assignability cache size:    260473
Identity cache size:          16941
Subtype cache size:           99375
Strict subtype cache size:     9253
I/O Read time:                0.08s
Parse time:                   0.73s
ResolveModule time:           0.20s
ResolveTypeReference time:    0.01s
Program time:                 1.11s
Bind time:                    0.42s
Check time:                  57.65s
transformTime time:           1.84s
Source Map time:              0.05s
commentTime time:             0.09s
I/O Write time:               0.32s
printTime time:               2.84s
Emit time:                    2.84s
Total time:                  62.02s

This should be a regression.
Memory usage increased from 1gb to 4gb and time increased from 23s to 62s.
Chief among them is a suspicious increase in the number of Symbols and Types.

But I personally don't mind letting it merge first to avoid blocking our development progress.

[nstepien]

@liuxingbaoyu might be related microsoft/TypeScript#50290 (comment)

[liuxingbaoyu]

@nstepien
Thank you for your reminder!
I've seen that one, and it shows up as a massive increase in Assignability cache size, but here it's Symbols and Types.

[liuxingbaoyu]

I'm sure I don't know what's going on.😅

[liuxingbaoyu]

Yes, as you can see, the CI turns green after adding a magic any.

This might have something to do with this across files.
When I extract Scope to the same file, it throws error.

packages/babel-traverse/src/path/index.ts:157:24 - error TS2345: Argument of type 'this' is not assignable to parameter of type 'NodePath<Scopable | Pattern>'.
  Type 'NodePath<T>' is not assignable to type 'NodePath<Scopable | Pattern>'.
    Type 'T' is not assignable to type 'Scopable | Pattern'.
      Type 'Node' is not assignable to type 'Scopable | Pattern'.
        Type 'ArrayExpression' is not assignable to type 'Scopable | Pattern'.
          Type 'ArrayExpression' is not assignable to type 'ArrayPattern'.
            Types of property 'type' are incompatible.
              Type '"ArrayExpression"' is not assignable to type '"ArrayPattern"'.
                Type 'T' is not assignable to type 'WhileStatement'.
                  Type 'Node' is not assignable to type 'WhileStatement'.
                    Type 'ArrayExpression' is missing the following properties from type 'WhileStatement': test, body

157     let a = new Scope2(this);

I think we can merge first, since our NodePath is so complex, it's not trivial to make even a minimal reproduction.

This works, too, without any other side effects.

   getScope(scope: Scope): Scope {
     return this.isScope()
       ? new Scope(this as NodePath<t.Pattern | t.Scopable>)
       : scope;
   }

[JLHwung]

When I extract Scope to the same file, it throws error.

Yeah the error is expected, new Scope must be guarded by the isScope check.

[liuxingbaoyu]

You're right, I seem to be closer to making a repo that reproduces, albeit just as complicated. 😂

[JLHwung]

@liuxingbaoyu A smaller reproduction will be great! I am drafting an issue to the TS repo. If you come up with a smaller reproduction, please let me know and I can update the issue.

[liuxingbaoyu]

https://github.com/liuxingbaoyu/babel-ts4.8-bug
To be honest, this might not be small enough for a human, but it's much more convenient for debugging and binary search.