Port microsoft/typescript-go#1757 #62501

ahejlsberg · 2025-09-28T13:34:50Z

ahejlsberg · 2025-09-28T13:35:12Z

typescript-bot · 2025-09-28T13:35:17Z

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

Copilot

Pull Request Overview

This PR ports a fix from the TypeScript Go repository (#1757) that addresses discriminated union type handling when discriminants are missing. The change modifies the discriminated union logic to better handle cases where union members lack discriminant properties.

Key Changes

Modified discriminant property checking logic in the type checker
Simplified conditional structure by combining null and literal type checks
Added test case demonstrating the fixed behavior with missing discriminants

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
`src/compiler/checker.ts`	Simplifies discriminant validation logic by combining discriminant existence and literal type checks
`tests/cases/compiler/missingDiscriminants2.ts`	Adds test case with union types having missing discriminant properties
`tests/baselines/reference/missingDiscriminants2.types`	Baseline for type checking results of the new test
`tests/baselines/reference/missingDiscriminants2.symbols`	Baseline for symbol resolution results of the new test
`tests/baselines/reference/missingDiscriminants2.errors.txt`	Baseline for expected error messages in the new test

Comments suppressed due to low confidence (1)

src/compiler/checker.ts:1

[nitpick] The refactored condition combines null check and literal type validation into a single statement, which is more concise. However, consider adding a comment explaining why we return undefined when either condition is met, as this affects discriminated union behavior.

import {

typescript-bot · 2025-09-28T13:59:19Z

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

There were interesting changes:

Branch only errors:

Package: css-tree
Error:

Error: 
/mnt/vss/_work/1/DefinitelyTyped/types/css-tree/css-tree-tests.ts
  18:11  error  TypeScript@local compile error: 
Parameter 'node' implicitly has an 'any' type                                                                                                                                                       @definitelytyped/expect
  18:17  error  TypeScript@local compile error: 
Parameter 'item' implicitly has an 'any' type                                                                                                                                                       @definitelytyped/expect
  18:23  error  TypeScript@local compile error: 
Parameter 'list' implicitly has an 'any' type                                                                                                                                                       @definitelytyped/expect
  19:9   error  TypeScript@local expected type to be:
  symbol
got:
  any                                                                                                                                                                            @definitelytyped/expect
  19:14  error  TypeScript@local compile error: 
Property 'break' does not exist on type 'WalkOptionsNoVisit | EnterOrLeaveFn<CssNode> | WalkOptionsVisit<ClassSelector>'.
  Property 'break' does not exist on type 'WalkOptionsNoVisit'            @definitelytyped/expect
  20:9   error  TypeScript@local expected type to be:
  symbol
got:
  any                                                                                                                                                                            @definitelytyped/expect
  20:14  error  TypeScript@local compile error: 
Property 'skip' does not exist on type 'WalkOptionsNoVisit | EnterOrLeaveFn<CssNode> | WalkOptionsVisit<ClassSelector>'.
  Property 'skip' does not exist on type 'WalkOptionsNoVisit'              @definitelytyped/expect
  21:9   error  TypeScript@local expected type to be:
  CssNode
got:
  any                                                                                                                                                                           @definitelytyped/expect
  21:14  error  TypeScript@local compile error: 
Property 'root' does not exist on type 'WalkOptionsNoVisit | EnterOrLeaveFn<CssNode> | WalkOptionsVisit<ClassSelector>'.
  Property 'root' does not exist on type 'WalkOptionsNoVisit'              @definitelytyped/expect
  22:9   error  TypeScript@local expected type to be:
  StyleSheet | null
got:
  any                                                                                                                                                                 @definitelytyped/expect
  22:14  error  TypeScript@local compile error: 
Property 'stylesheet' does not exist on type 'WalkOptionsNoVisit | EnterOrLeaveFn<CssNode> | WalkOptionsVisit<ClassSelector>'.
  Property 'stylesheet' does not exist on type 'WalkOptionsNoVisit'  @definitelytyped/expect
  23:9   error  TypeScript@local expected type to be:
  ClassSelector
got:
  any                                                                                                                                                                     @definitelytyped/expect
  24:9   error  TypeScript@local expected type to be:
  ListItem<CssNode>
got:
  any                                                                                                                                                                 @definitelytyped/expect
  25:9   error  TypeScript@local expected type to be:
  List<CssNode>
got:
  any                                                                                                                                                                     @definitelytyped/expect
  26:9   error  TypeScript@local expected type to be:
  Atrule | null
got:
  any                                                                                                                                                                     @definitelytyped/expect
  26:14  error  TypeScript@local compile error: 
Property 'atrule' does not exist on type 'WalkOptionsNoVisit | EnterOrLeaveFn<CssNode> | WalkOptionsVisit<ClassSelector>'.
  Property 'atrule' does not exist on type 'WalkOptionsNoVisit'          @definitelytyped/expect
  28:11  error  TypeScript@local compile error: 
Parameter 'node' implicitly has an 'any' type                                                                                                                                                       @definitelytyped/expect
  28:17  error  TypeScript@local compile error: 
Parameter 'item' implicitly has an 'any' type                                                                                                                                                       @definitelytyped/expect
  28:23  error  TypeScript@local compile error: 
Parameter 'list' implicitly has an 'any' type                                                                                                                                                       @definitelytyped/expect
  29:9   error  TypeScript@local expected type to be:
  symbol
got:
  any                                                                                                                                                                            @definitelytyped/expect
  29:14  error  TypeScript@local compile error: 
Property 'break' does not exist on type 'WalkOptionsNoVisit | EnterOrLeaveFn<CssNode> | WalkOptionsVisit<ClassSelector>'.
  Property 'break' does not exist on type 'WalkOptionsNoVisit'            @definitelytyped/expect
  30:9   error  TypeScript@local expected type to be:
  symbol
got:
  any                                                                                                                                                                            @definitelytyped/expect
  30:14  error  TypeScript@local compile error: 
Property 'skip' does not exist on type 'WalkOptionsNoVisit | EnterOrLeaveFn<CssNode> | WalkOptionsVisit<ClassSelector>'.
  Property 'skip' does not exist on type 'WalkOptionsNoVisit'              @definitelytyped/expect
  31:9   error  TypeScript@local expected type to be:
  CssNode
got:
  any                                                                                                                                                                           @definitelytyped/expect
  31:14  error  TypeScript@local compile error: 
Property 'root' does not exist on type 'WalkOptionsNoVisit | EnterOrLeaveFn<CssNode> | WalkOptionsVisit<ClassSelector>'.
  Property 'root' does not exist on type 'WalkOptionsNoVisit'              @definitelytyped/expect
  32:9   error  TypeScript@local expected type to be:
  StyleSheet | null
got:
  any                                                                                                                                                                 @definitelytyped/expect
  32:14  error  TypeScript@local compile error: 
Property 'stylesheet' does not exist on type 'WalkOptionsNoVisit | EnterOrLeaveFn<CssNode> | WalkOptionsVisit<ClassSelector>'.
  Property 'stylesheet' does not exist on type 'WalkOptionsNoVisit'  @definitelytyped/expect
  33:9   error  TypeScript@local expected type to be:
  ClassSelector
got:
  any                                                                                                                                                                     @definitelytyped/expect
  34:9   error  TypeScript@local expected type to be:
  ListItem<CssNode>
got:
  any                                                                                                                                                                 @definitelytyped/expect
  35:9   error  TypeScript@local expected type to be:
  List<CssNode>
got:
  any                                                                                                                                                                     @definitelytyped/expect
  36:9   error  TypeScript@local expected type to be:
  Atrule | null
got:
  any                                                                                                                                                                     @definitelytyped/expect
  36:14  error  TypeScript@local compile error: 
Property 'atrule' does not exist on type 'WalkOptionsNoVisit | EnterOrLeaveFn<CssNode> | WalkOptionsVisit<ClassSelector>'.
  Property 'atrule' does not exist on type 'WalkOptionsNoVisit'          @definitelytyped/expect

✖ 32 problems (32 errors, 0 warnings)

    at combineErrorsAndWarnings (/mnt/vss/_work/1/DefinitelyTyped/node_modules/.pnpm/@definitelytyped+dtslint@0.2.34_typescript@6.0.0-dev.20250928/node_modules/@definitelytyped/dtslint/dist/index.js:199:28)
    at runTests (/mnt/vss/_work/1/DefinitelyTyped/node_modules/.pnpm/@definitelytyped+dtslint@0.2.34_typescript@6.0.0-dev.20250928/node_modules/@definitelytyped/dtslint/dist/index.js:191:20)

You can check the log here.

typescript-bot · 2025-09-28T14:02:08Z

@ahejlsberg Here are the results of running the user tests with tsc comparing main and refs/pull/62501/merge:

There were infrastructure failures potentially unrelated to your change:

1 instance of "Git clone failed"

Otherwise...

Everything looks good!

typescript-bot · 2025-09-28T14:23:25Z

@ahejlsberg
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}	_{193,398k (± 0.77%)}	_{193,945k (± 0.96%)}	_~	_192,724k	_196,376k	_{p=0.230 n=6}
_{Parse Time}	_{1.29s (± 0.63%)}	_{1.30s (± 0.58%)}	_~	_1.29s	_1.31s	_{p=0.120 n=6}
_{Bind Time}	_{0.72s (± 0.57%)}	_0.72s	_~	_~	_~	_{p=0.405 n=6}
_{Check Time}	_{9.77s (± 0.46%)}	_{9.73s (± 0.48%)}	_~	_9.68s	_9.81s	_{p=0.228 n=6}
_{Emit Time}	_{2.75s (± 0.78%)}	_{2.75s (± 0.86%)}	_~	_2.72s	_2.79s	_{p=0.746 n=6}
_{Total Time}	_{14.54s (± 0.39%)}	_{14.51s (± 0.39%)}	_~	_14.45s	_14.60s	_{p=0.421 n=6}
_{angular-1 - node (v18.15.0, x64)}
_Errors	₁	₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_948,914	_948,812	_{-102 (- 0.01%)}	_~	_~	_{p=0.001 n=6}
_Types	_410,884	_410,869	_{-15 (- 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{1,245,599k (± 0.00%)}	_{1,245,541k (± 0.00%)}	_~	_1,245,476k	_1,245,618k	_{p=0.066 n=6}
_{Parse Time}	_{6.49s (± 1.03%)}	_{6.50s (± 0.74%)}	_~	_6.45s	_6.58s	_{p=0.377 n=6}
_{Bind Time}	_{1.87s (± 0.40%)}	_{1.88s (± 0.29%)}	_~	_1.87s	_1.88s	_{p=0.476 n=6}
_{Check Time}	_{32.24s (± 0.28%)}	_{32.24s (± 0.23%)}	_~	_32.11s	_32.34s	_{p=1.000 n=6}
_{Emit Time}	_{14.77s (± 0.37%)}	_{14.81s (± 0.42%)}	_~	_14.71s	_14.90s	_{p=0.421 n=6}
_{Total Time}	_{55.37s (± 0.37%)}	_{55.42s (± 0.20%)}	_~	_55.27s	_55.58s	_{p=0.422 n=6}
_{mui-docs - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_2,544,632	_2,544,624	_{-8 (- 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_903,208	_903,207	_{-1 (- 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{2,829,870k (± 0.01%)}	_{2,829,900k (± 0.01%)}	_~	_2,829,710k	_2,830,104k	_{p=0.575 n=6}
_{Parse Time}	_{8.72s (± 0.41%)}	_{8.71s (± 0.39%)}	_~	_8.65s	_8.75s	_{p=0.872 n=6}
_{Bind Time}	_{2.19s (± 0.24%)}	_{2.20s (± 0.55%)}	_~	_2.18s	_2.21s	_{p=0.142 n=6}
_{Check Time}	_{86.74s (± 1.13%)}	_{86.60s (± 1.35%)}	_~	_85.75s	_88.15s	_{p=0.298 n=6}
_{Emit Time}	_{0.34s (±29.11%)}	_{0.62s (±125.19%)}	_~	_0.30s	_2.20s	_{p=0.787 n=6}
_{Total Time}	_{97.99s (± 0.98%)}	_{98.13s (± 1.21%)}	_~	_96.98s	_99.30s	_{p=0.810 n=6}
_{self-build-src - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,237,064	_1,237,064	_~	_~	_~	_{p=1.000 n=6}
_Types	_259,743	_259,743	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{2,425,016k (± 6.12%)}	_{2,364,458k (± 0.01%)}	_~	_2,364,264k	_2,364,893k	_{p=0.936 n=6}
_{Parse Time}	_{5.14s (± 0.69%)}	_{5.15s (± 1.28%)}	_~	_5.08s	_5.24s	_{p=0.810 n=6}
_{Bind Time}	_{1.77s (± 0.55%)}	_{1.78s (± 0.92%)}	_~	_1.76s	_1.80s	_{p=0.934 n=6}
_{Check Time}	_{35.05s (± 0.68%)}	_{35.13s (± 0.33%)}	_~	_34.99s	_35.26s	_{p=0.574 n=6}
_{Emit Time}	_{3.00s (± 0.46%)}	_{3.03s (± 1.99%)}	_~	_2.96s	_3.13s	_{p=0.296 n=6}
_{Total Time}	_{44.99s (± 0.50%)}	_{45.08s (± 0.27%)}	_~	_44.91s	_45.21s	_{p=0.575 n=6}
_{self-build-src-public-api - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_1,237,064	_1,237,064	_~	_~	_~	_{p=1.000 n=6}
_Types	_259,743	_259,743	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{3,158,348k (± 0.02%)}	_{3,158,381k (± 0.04%)}	_~	_3,156,854k	_3,159,950k	_{p=1.000 n=6}
_{Parse Time}	_{6.85s (± 0.79%)}	_{6.86s (± 0.64%)}	_~	_6.79s	_6.91s	_{p=0.748 n=6}
_{Bind Time}	_{2.16s (± 1.23%)}	_{2.14s (± 1.43%)}	_~	_2.09s	_2.18s	_{p=0.226 n=6}
_{Check Time}	_{42.57s (± 0.23%)}	_{42.61s (± 0.29%)}	_~	_42.46s	_42.74s	_{p=0.521 n=6}
_{Emit Time}	_{3.50s (± 2.43%)}	_{3.51s (± 2.49%)}	_~	_3.37s	_3.62s	_{p=0.936 n=6}
_{Total Time}	_{55.09s (± 0.24%)}	_{55.14s (± 0.34%)}	_~	_54.91s	_55.39s	_{p=0.688 n=6}
_{self-compiler - node (v18.15.0, x64)}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_262,412	_262,412	_~	_~	_~	_{p=1.000 n=6}
_Types	_103,924	_103,924	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{440,512k (± 0.01%)}	_{440,508k (± 0.01%)}	_~	_440,444k	_440,558k	_{p=1.000 n=6}
_{Parse Time}	_{3.52s (± 1.49%)}	_{3.51s (± 0.58%)}	_~	_3.47s	_3.52s	_{p=0.360 n=6}
_{Bind Time}	_{1.32s (± 1.30%)}	_{1.32s (± 1.42%)}	_~	_1.28s	_1.33s	_{p=0.455 n=6}
_{Check Time}	_{19.00s (± 0.33%)}	_{18.99s (± 0.36%)}	_~	_18.87s	_19.06s	_{p=0.936 n=6}
_{Emit Time}	_{1.53s (± 1.69%)}	_{1.54s (± 1.42%)}	_~	_1.51s	_1.57s	_{p=0.373 n=6}
_{Total Time}	_{25.36s (± 0.45%)}	_{25.36s (± 0.25%)}	_~	_25.26s	_25.45s	_{p=1.000 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}	_{370,048k (± 0.04%)}	_{370,098k (± 0.03%)}	_~	_369,998k	_370,220k	_{p=0.378 n=6}
_{Parse Time}	_{2.83s (± 0.32%)}	_{2.85s (± 1.19%)}	_~	_2.81s	_2.89s	_{p=0.292 n=6}
_{Bind Time}	_{1.60s (± 1.02%)}	_{1.59s (± 0.62%)}	_~	_1.58s	_1.60s	_{p=0.117 n=6}
_{Check Time}	_{16.45s (± 0.27%)}	_{16.53s (± 0.58%)}	_~	_16.45s	_16.71s	_{p=0.107 n=6}
_{Emit Time}	_{0.00s (±244.70%)}	_0.00s	_~	_~	_~	_{p=0.405 n=6}
_{Total Time}	_{20.89s (± 0.26%)}	_{20.97s (± 0.53%)}	_~	_20.88s	_21.19s	_{p=0.143 n=6}
_{vscode - node (v18.15.0, x64)}
_Errors	₁	₁	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_3,890,940	_3,890,959	_{+19 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_Types	_1,224,250	_1,224,257	_{+7 (+ 0.00%)}	_~	_~	_{p=0.001 n=6}
_{Memory used}	_{3,704,544k (± 0.01%)}	_{3,704,490k (± 0.01%)}	_~	_3,704,207k	_3,704,640k	_{p=0.471 n=6}
_{Parse Time}	_{15.14s (± 0.70%)}	_{15.18s (± 0.76%)}	_~	_14.98s	_15.31s	_{p=0.574 n=6}
_{Bind Time}	_{4.90s (± 0.76%)}	_{4.90s (± 0.66%)}	_~	_4.88s	_4.96s	_{p=1.000 n=6}
_{Check Time}	_{103.67s (± 5.25%)}	_{99.77s (± 0.33%)}	_~	_99.33s	_100.25s	_{p=0.173 n=6}
_{Emit Time}	_{40.51s (±17.06%)}	_{34.51s (±19.63%)}	_~	_30.40s	_47.24s	_{p=0.066 n=6}
_{Total Time}	_{164.23s (± 4.74%)}	_{154.36s (± 4.46%)}	_{🟩-9.87s (- 6.01%)}	_149.96s	_167.34s	_{p=0.031 n=6}
_{webpack - node (v18.15.0, x64)}
_Errors	₃₈	₃₈	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_361,753	_361,753	_~	_~	_~	_{p=1.000 n=6}
_Types	_158,862	_158,862	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{516,556k (± 0.02%)}	_{516,452k (± 0.02%)}	_~	_516,351k	_516,550k	_{p=0.066 n=6}
_{Parse Time}	_{4.46s (± 0.46%)}	_{4.45s (± 1.11%)}	_~	_4.39s	_4.53s	_{p=0.687 n=6}
_{Bind Time}	_{1.90s (± 1.88%)}	_{1.91s (± 2.14%)}	_~	_1.87s	_1.98s	_{p=1.000 n=6}
_{Check Time}	_{21.79s (± 0.21%)}	_{21.77s (± 0.28%)}	_~	_21.67s	_21.84s	_{p=0.521 n=6}
_{Emit Time}	_0.00s	_{0.00s (±244.70%)}	_~	_0.00s	_0.01s	_{p=0.405 n=6}
_{Total Time}	_{28.14s (± 0.23%)}	_{28.13s (± 0.31%)}	_~	_27.97s	_28.20s	_{p=0.936 n=6}
_{xstate-main - node (v18.15.0, x64)}
_Errors	₃₀	₃₀	_~	_~	_~	_{p=1.000 n=6}
_Symbols	_672,790	_672,790	_~	_~	_~	_{p=1.000 n=6}
_Types	_201,962	_201,962	_~	_~	_~	_{p=1.000 n=6}
_{Memory used}	_{574,902k (± 0.02%)}	_{574,934k (± 0.02%)}	_~	_574,700k	_575,017k	_{p=0.575 n=6}
_{Parse Time}	_{4.18s (± 0.53%)}	_{4.20s (± 0.82%)}	_~	_4.17s	_4.25s	_{p=0.285 n=6}
_{Bind Time}	_{1.33s (± 1.29%)}	_{1.34s (± 0.62%)}	_~	_1.34s	_1.36s	_{p=0.096 n=6}
_{Check Time}	_{20.67s (± 2.18%)}	_{20.38s (± 1.16%)}	_~	_20.16s	_20.84s	_{p=0.423 n=6}
_{Emit Time}	_0.00s	_{0.00s (±244.70%)}	_~	_0.00s	_0.01s	_{p=0.405 n=6}
_{Total Time}	_{26.18s (± 1.65%)}	_{25.92s (± 0.87%)}	_~	_25.75s	_26.37s	_{p=0.471 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 · 2025-09-28T14:50:47Z

@ahejlsberg Here are the results of running the top 400 repos with tsc comparing main and refs/pull/62501/merge:

Everything looks good!

jakebailey · 2025-09-28T21:23:24Z

Seems like there's a break?

ahejlsberg · 2025-09-29T13:45:51Z

Seems like there's a break?

Yes, that's the same break that caused us to look at the issue in the first place. The problem is that the WalkOptions union includes a WalkOptionsNoVisit constituent that doesn't declare a discriminant. The discrimination logic used to eliminate it, but that isn't correct and doesn't happen following #61828 and this PR.

The fix is to add a visit discriminant property to WalkOptionsNoVisit:

export interface WalkOptionsNoVisit {
    visit?: never;
    enter?: EnterOrLeaveFn | undefined;
    leave?: EnterOrLeaveFn | undefined;
    reverse?: boolean | undefined;
}

jakebailey · 2025-09-29T20:34:18Z

@typescript-bot run dt

typescript-bot · 2025-09-29T20:34:23Z

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

Command	Status	Results
`run dt`	✅ Started	✅ Results

typescript-bot · 2025-09-29T20:57:51Z

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

Everything looks the same!

You can check the log here.

ahejlsberg added 2 commits September 28, 2025 09:32

Port microsoft/typescript-go#1757

4e59e52

Add regression test

f939285

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ahejlsberg requested a review from jakebailey September 28, 2025 13:37

jakebailey mentioned this pull request Sep 28, 2025

Fix translation error that disabled union discrimination optimization microsoft/typescript-go#1757

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jakebailey mentioned this pull request Sep 29, 2025

[css-tree] Add missing visit method to WalkOptionsNoVisit DefinitelyTyped/DefinitelyTyped#73777

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ahejlsberg merged commit 97610a8 into main Sep 29, 2025
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ahejlsberg deleted the port-tsgo-1757 branch September 29, 2025 21:42

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Port microsoft/typescript-go#1757 #62501

Port microsoft/typescript-go#1757 #62501

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Port microsoft/typescript-go#1757 #62501

Port microsoft/typescript-go#1757 #62501

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