Remove no-default-lib #62435

jakebailey · 2025-09-11T16:35:13Z

typescript-bot · 2025-09-11T16:35:31Z

Looks like you're introducing a change to the public API surface area. If this includes breaking changes, please document them on our wiki's API Breaking Changes page.

Also, please make sure @DanielRosenwasser and @RyanCavanaugh are aware of the changes, just as a heads up.

jakebailey · 2025-09-11T16:35:46Z

@typescript-bot test it

Copilot

Pull Request Overview

This PR removes the no-default-lib TypeScript compiler directive feature. The change ensures that default TypeScript libraries are always included in compilation unless explicitly excluded through compiler options, eliminating a source of confusion where individual files could opt out of standard library inclusion.

Removes processing and handling of the no-default-lib directive
Updates test baselines to reflect that default libraries are now always included
Marks the hasNoDefaultLib property as deprecated in the public API

Reviewed Changes

Copilot reviewed 59 out of 62 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tests/baselines/reference/tsxResolveExternalModuleExportsTypes.types	Updates performance stats to reflect increased type counts from including libraries
tests/baselines/reference/tsserver/configuredProjects/should-not-close-configured-project-after-closing-last-open-file,-but-should-be-closed-on-next-file-open-if-its-not-the-file-from-same-project.js	Adds default library information in project output
tests/baselines/reference/tscWatch/programUpdates/when-skipLibCheck-and-skipDefaultLibCheck-changes.js	Removes library-related errors that no longer occur
tests/baselines/reference/tscWatch/libraryResolution/*.js	Updates library resolution order and removes duplicate lib entries
tests/baselines/reference/tsc/libraryResolution/*.js	Updates shape signatures order for library files
tests/baselines/reference/tsc/incremental/ts-file-with-no-default-lib-that-augments-the-global-scope.js	Adds additional library files and errors from forced inclusion
tests/baselines/reference/project/noDefaultLib/*.json	Adds default library files to resolved inputs
tests/baselines/reference/noDefaultLib.*	Shows library symbols now merged with user-defined interfaces
tests/baselines/reference/api/typescript.d.ts	Marks `hasNoDefaultLib` and `isLibFile` properties as deprecated
tests/baselines/reference/declarationEmitPreservesHasNoDefaultLibDirective.	Removes the `no-default-lib` directive from emitted declarations

typescript-bot · 2025-09-11T16:35:52Z

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
`test top400`	✅ Started	✅ Results
`user test this`	✅ Started	✅ Results
`run dt`	✅ Started	👀 Results
`perf test this faster`	✅ Started	👀 Results

typescript-bot · 2025-09-11T16:58:57Z

Hey @jakebailey, the results of running the DT tests are ready.

There were interesting changes:

Branch only errors:

Package: miniprogram-wxs
Error:

Error: 
/mnt/vss/_work/1/DefinitelyTyped/types/miniprogram-wxs/miniprogram-wxs-tests.ts
   7:1  error  TypeScript@local compile error: 
Unused '@ts-expect-error' directive  @definitelytyped/expect
  10:1  error  TypeScript@local compile error: 
Unused '@ts-expect-error' directive  @definitelytyped/expect

✖ 2 problems (2 errors, 0 warnings)

    at combineErrorsAndWarnings (/mnt/vss/_work/1/DefinitelyTyped/node_modules/.pnpm/@[email protected][email protected]/node_modules/@definitelytyped/dtslint/dist/index.js:199:28)
    at runTests (/mnt/vss/_work/1/DefinitelyTyped/node_modules/.pnpm/@[email protected][email protected]/node_modules/@definitelytyped/dtslint/dist/index.js:191:20)

You can check the log here.

typescript-bot · 2025-09-11T17:00:25Z

@jakebailey Here are the results of running the user tests with tsc comparing main and refs/pull/62435/merge:

There were infrastructure failures potentially unrelated to your change:

1 instance of "Git clone failed"

Otherwise...

Everything looks good!

typescript-bot · 2025-09-11T17:32:26Z

@jakebailey
The results of the perf run you requested are in!

Here they are:

tsc

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-Unions - node (v18.15.0, x64)}
_Errors	₃₄	₃₄	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_62,370	_62,370	_~	_~	_~	_{p=1.000 n=6}
_Types	_50,386	_50,386	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{195,223k (± 0.96%)}	_{193,999k (± 0.96%)}	_~	_192,746k	_196,421k	_{p=0.173 n=6}
_{Parse Time}	_{1.30s (± 0.58%)}	_{1.30s (± 0.58%)}	_~	_1.29s	_1.31s	_{p=1.000 n=6}
_{Bind Time}	_0.72s	_0.72s	_~	_~	_~	_{p=1.000 n=6}
_{Check Time}	_{9.73s (± 0.20%)}	_{9.74s (± 0.38%)}	_~	_9.71s	_9.80s	_{p=1.000 n=6}
_{Emit Time}	_{2.74s (± 0.68%)}	_{2.74s (± 0.54%)}	_~	_2.72s	_2.76s	_{p=0.808 n=6}
_{Total Time}	_{14.50s (± 0.25%)}	_{14.51s (± 0.24%)}	_~	_14.47s	_14.57s	_{p=0.808 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₁	₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_948,914	_948,914	_~	_~	_~	_{p=1.000 n=6}
_Types	_410,884	_410,884	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{1,245,603k (± 0.01%)}	_{1,245,614k (± 0.00%)}	_~	_1,245,583k	_1,245,627k	_{p=0.689 n=6}
_{Parse Time}	_{6.53s (± 0.77%)}	_{6.51s (± 0.32%)}	_~	_6.49s	_6.55s	_{p=1.000 n=6}
_{Bind Time}	_{1.87s (± 0.28%)}	_{1.87s (± 0.59%)}	_~	_1.85s	_1.88s	_{p=0.784 n=6}
_{Check Time}	_{32.16s (± 0.40%)}	_{32.15s (± 0.35%)}	_~	_32.01s	_32.32s	_{p=0.748 n=6}
_{Emit Time}	_{14.79s (± 0.43%)}	_{14.87s (± 0.56%)}	_~	_14.81s	_15.04s	_{p=0.107 n=6}
_{Total Time}	_{55.36s (± 0.30%)}	_{55.40s (± 0.36%)}	_~	_55.23s	_55.75s	_{p=1.000 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,542,233	_2,542,233	_~	_~	_~	_{p=1.000 n=6}
_Types	_902,605	_902,605	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,827,015k (± 0.00%)}	_{2,826,967k (± 0.00%)}	_~	_2,826,924k	_2,827,029k	_{p=0.810 n=6}
_{Parse Time}	_{10.49s (± 0.62%)}	_{10.53s (± 0.69%)}	_~	_10.42s	_10.65s	_{p=0.325 n=6}
_{Bind Time}	_{2.63s (± 0.70%)}	_{2.63s (± 0.52%)}	_~	_2.60s	_2.64s	_{p=0.743 n=6}
_{Check Time}	_{103.59s (± 1.16%)}	_{105.38s (± 3.12%)}	_~	_102.26s	_109.61s	_{p=0.471 n=6}
_{Emit Time}	_{0.38s (± 2.88%)}	_{0.38s (± 2.17%)}	_~	_0.36s	_0.38s	_{p=1.000 n=6}
_{Total Time}	_{117.09s (± 1.02%)}	_{118.92s (± 2.81%)}	_~	_115.66s	_123.17s	_{p=0.471 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,237,019	_1,237,032	_{+13 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_259,717	_259,718	_{+1 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,546,755k (±11.94%)}	_{2,364,668k (± 0.03%)}	_~	_2,364,081k	_2,366,104k	_{p=0.093 n=6}
_{Parse Time}	_{5.16s (± 1.87%)}	_{5.16s (± 0.63%)}	_~	_5.12s	_5.21s	_{p=0.688 n=6}
_{Bind Time}	_{1.77s (± 1.38%)}	_{1.78s (± 0.97%)}	_~	_1.76s	_1.81s	_{p=0.291 n=6}
_{Check Time}	_{35.02s (± 0.86%)}	_{35.13s (± 0.54%)}	_~	_34.94s	_35.46s	_{p=0.423 n=6}
_{Emit Time}	_{2.98s (± 1.28%)}	_{2.99s (± 2.18%)}	_~	_2.91s	_3.06s	_{p=0.936 n=6}
_{Total Time}	_{44.95s (± 0.78%)}	_{45.09s (± 0.57%)}	_~	_44.91s	_45.55s	_{p=0.468 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,237,019	_1,237,032	_{+13 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_259,717	_259,718	_{+1 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{3,158,741k (± 0.01%)}	_{3,158,588k (± 0.01%)}	_~	_3,158,001k	_3,159,040k	_{p=0.575 n=6}
_{Parse Time}	_{8.42s (± 0.59%)}	_{8.41s (± 0.33%)}	_~	_8.38s	_8.46s	_{p=0.575 n=6}
_{Bind Time}	_{2.61s (± 1.04%)}	_{2.64s (± 1.82%)}	_~	_2.59s	_2.71s	_{p=0.574 n=6}
_{Check Time}	_{52.84s (± 0.40%)}	_{52.66s (± 0.22%)}	_~	_52.53s	_52.82s	_{p=0.093 n=6}
_{Emit Time}	_{4.35s (± 2.29%)}	_{4.35s (± 1.67%)}	_~	_4.28s	_4.48s	_{p=0.810 n=6}
_{Total Time}	_{68.23s (± 0.24%)}	_{68.06s (± 0.16%)}	_~	_67.88s	_68.18s	_{p=0.093 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_262,423	_262,419	_{-4 (- 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_103,918	_103,917	_{-1 (- 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{440,602k (± 0.04%)}	_{440,530k (± 0.01%)}	_~	_440,504k	_440,575k	_{p=0.298 n=6}
_{Parse Time}	_{2.90s (± 0.42%)}	_{2.87s (± 0.68%)}	_{-0.02s (- 0.75%)}	_2.85s	_2.90s	_{p=0.036 n=6}
_{Bind Time}	_{1.11s (± 0.37%)}	_{1.12s (± 0.49%)}	_~	_1.11s	_1.12s	_{p=0.282 n=6}
_{Check Time}	_{15.85s (± 0.51%)}	_{15.84s (± 0.42%)}	_~	_15.75s	_15.95s	_{p=0.810 n=6}
_{Emit Time}	_{1.31s (± 1.90%)}	_{1.32s (± 0.80%)}	_~	_1.30s	_1.33s	_{p=1.000 n=6}
_{Total Time}	_{21.17s (± 0.37%)}	_{21.15s (± 0.31%)}	_~	_21.06s	_21.24s	_{p=0.687 n=6}
_{ts-pre-modules - node (v18.15.0, x64)}
_Errors	₇₂	₇₂	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_225,367	_225,367	_~	_~	_~	_{p=1.000 n=6}
_Types	_94,290	_94,290	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{370,073k (± 0.05%)}	_{370,037k (± 0.03%)}	_~	_369,927k	_370,183k	_{p=1.000 n=6}
_{Parse Time}	_{2.84s (± 1.25%)}	_{2.81s (± 0.88%)}	_~	_2.78s	_2.85s	_{p=0.124 n=6}
_{Bind Time}	_{1.61s (± 1.32%)}	_{1.59s (± 1.40%)}	_~	_1.56s	_1.61s	_{p=0.223 n=6}
_{Check Time}	_{16.47s (± 0.45%)}	_{16.42s (± 0.52%)}	_~	_16.28s	_16.52s	_{p=0.261 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{20.93s (± 0.50%)}	_{20.82s (± 0.51%)}	_~	_20.69s	_20.93s	_{p=0.109 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₁	₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_3,897,295	_3,897,295	_~	_~	_~	_{p=1.000 n=6}
_Types	_1,227,220	_1,227,220	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{3,716,850k (± 0.01%)}	_{3,716,879k (± 0.01%)}	_~	_3,716,421k	_3,717,337k	_{p=0.936 n=6}
_{Parse Time}	_{18.84s (± 0.40%)}	_{18.83s (± 0.57%)}	_~	_18.71s	_19.02s	_{p=1.000 n=6}
_{Bind Time}	_{6.07s (± 0.55%)}	_{6.07s (± 0.36%)}	_~	_6.05s	_6.11s	_{p=1.000 n=6}
_{Check Time}	_{124.74s (± 2.43%)}	_{126.15s (± 4.60%)}	_~	_122.11s	_134.10s	_{p=0.810 n=6}
_{Emit Time}	_{41.13s (±18.06%)}	_{42.00s (±18.36%)}	_~	_37.36s	_56.20s	_{p=0.575 n=6}
_{Total Time}	_{190.78s (± 3.25%)}	_{193.05s (± 5.04%)}	_~	_184.33s	_204.80s	_{p=0.936 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₃₇	₃₇	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_361,535	_361,535	_~	_~	_~	_{p=1.000 n=6}
_Types	_158,752	_158,752	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{515,751k (± 0.02%)}	_{515,817k (± 0.03%)}	_~	_515,648k	_516,073k	_{p=0.575 n=6}
_{Parse Time}	_{5.53s (± 0.27%)}	_{5.52s (± 0.87%)}	_~	_5.44s	_5.57s	_{p=1.000 n=6}
_{Bind Time}	_{2.38s (± 1.61%)}	_{2.36s (± 1.07%)}	_~	_2.33s	_2.39s	_{p=0.332 n=6}
_{Check Time}	_{27.04s (± 0.44%)}	_{26.99s (± 0.48%)}	_~	_26.86s	_27.22s	_{p=0.470 n=6}
_{Emit Time}	_{0.00s (±154.76%)}	_0.00s	_~	_~	_~	_{p=0.174 n=6}
_{Total Time}	_{34.95s (± 0.35%)}	_{34.88s (± 0.39%)}	_~	_34.70s	_35.10s	_{p=0.423 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₃₀	₃₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_668,465	_668,465	_~	_~	_~	_{p=1.000 n=6}
_Types	_200,558	_200,558	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{572,153k (± 0.03%)}	_{572,212k (± 0.03%)}	_~	_572,045k	_572,447k	_{p=0.521 n=6}
_{Parse Time}	_{4.18s (± 0.76%)}	_{4.16s (± 0.29%)}	_~	_4.14s	_4.17s	_{p=0.090 n=6}
_{Bind Time}	_{1.33s (± 1.38%)}	_{1.33s (± 0.57%)}	_~	_1.32s	_1.34s	_{p=0.934 n=6}
_{Check Time}	_{20.57s (± 1.70%)}	_{20.46s (± 1.97%)}	_~	_20.01s	_20.87s	_{p=0.810 n=6}
_{Emit Time}	_0.00s	_0.00s	_~	_~	_~	_{p=1.000 n=6}
_{Total Time}	_{26.07s (± 1.46%)}	_{25.94s (± 1.53%)}	_~	_25.50s	_26.35s	_{p=0.575 n=6}

System info unknown

Hosts

node (v18.15.0, x64)

Scenarios

Compiler-Unions - node (v18.15.0, x64)
angular-1 - node (v18.15.0, x64)
mui-docs - node (v18.15.0, x64)
self-build-src - node (v18.15.0, x64)
self-build-src-public-api - node (v18.15.0, x64)
self-compiler - node (v18.15.0, x64)
ts-pre-modules - node (v18.15.0, x64)
vscode - node (v18.15.0, x64)
webpack - node (v18.15.0, x64)
xstate-main - node (v18.15.0, x64)

_Benchmark	_Name	_Iterations
_Current	_pr	₆
_Baseline	_baseline	₆

Developer Information:

Download Benchmarks

typescript-bot · 2025-09-11T17:57:54Z

@jakebailey Here are the results of running the top 400 repos with tsc comparing main and refs/pull/62435/merge:

Everything looks good!

...ines/reference/tsc/incremental/ts-file-with-no-default-lib-that-augments-the-global-scope.js

...aselines/reference/tsc/libraryResolution/when-one-of-the-file-skips-default-lib-inclusion.js

...lines/reference/tscWatch/programUpdates/when-skipLibCheck-and-skipDefaultLibCheck-changes.js

src/compiler/builder.ts

jakebailey · 2025-09-12T16:29:29Z

This PR fails in CI but passes locally. I have no idea what's going on with that.

sheetalkamat · 2025-09-12T16:39:37Z

Try printing diff on failing baseline and see what it is?

jakebailey · 2025-09-12T16:41:33Z

Oh, I just have to merge main. I'm touching new tests.

jakebailey · 2025-09-12T18:46:37Z

@typescript-bot user test this
@typescript-bot run dt
@typescript-bot test top800

typescript-bot · 2025-09-12T18:46:43Z

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
`user test this`	✅ Started	✅ Results
`run dt`	✅ Started	👀 Results
`test top800`	✅ Started	✅ Results

typescript-bot · 2025-09-12T19:09:08Z

Hey @jakebailey, the results of running the DT tests are ready.

There were interesting changes:

Branch only errors:

Package: miniprogram-wxs
Error:

Error: 
/mnt/vss/_work/1/DefinitelyTyped/types/miniprogram-wxs/miniprogram-wxs-tests.ts
   7:1  error  TypeScript@local compile error: 
Unused '@ts-expect-error' directive  @definitelytyped/expect
  10:1  error  TypeScript@local compile error: 
Unused '@ts-expect-error' directive  @definitelytyped/expect

✖ 2 problems (2 errors, 0 warnings)

    at combineErrorsAndWarnings (/mnt/vss/_work/1/DefinitelyTyped/node_modules/.pnpm/@[email protected][email protected]/node_modules/@definitelytyped/dtslint/dist/index.js:199:28)
    at runTests (/mnt/vss/_work/1/DefinitelyTyped/node_modules/.pnpm/@[email protected][email protected]/node_modules/@definitelytyped/dtslint/dist/index.js:191:20)

You can check the log here.

typescript-bot · 2025-09-12T19:11:47Z

@jakebailey Here are the results of running the user tests with tsc comparing main and refs/pull/62435/merge:

There were infrastructure failures potentially unrelated to your change:

1 instance of "Git clone failed"

Otherwise...

Everything looks good!

typescript-bot · 2025-09-12T21:15:03Z

@jakebailey Here are the results of running the top 800 repos with tsc comparing main and refs/pull/62435/merge:

Everything looks good!

jakebailey · 2025-09-12T21:17:39Z

This is basically impossible to review, so I tried to split the PR into two commits.

src/compiler/program.ts

sheetalkamat · 2025-09-15T18:05:43Z

Its very difficult to add comment at right place so just writing at a comment here

If we can add "defaultLibName" as well into the libFiles path, then isDefaultLibrary becomes just check to see if path is in "LibFiles" set. (Check corsa)

jakebailey · 2025-09-16T18:03:06Z

Which isDefaultLibrary you referring to? The testing one? I was under the impression that we had to call it in places without a Program available, but maybe you mean another function?

sheetalkamat · 2025-09-16T19:26:22Z

u mean another function?

isSourceFileDefaultLibrary in program.ts

Copilot AI review requested due to automatic review settings September 11, 2025 16:35

github-project-automation bot added this to PR Backlog Sep 11, 2025

github-project-automation bot moved this to Not started in PR Backlog Sep 11, 2025

typescript-bot assigned jakebailey Sep 11, 2025

typescript-bot added Author: Team For Milestone Bug PRs that fix a bug with a specific milestone labels Sep 11, 2025

Copilot AI reviewed Sep 11, 2025

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jakebailey marked this pull request as draft September 11, 2025 17:15