Microsoft/TypeScript

Crash: RangeError: Maximum call stack size exceeded in addTypesToUnion when using incomplete keyof type annotation on object destructuring

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#62993 opened on Jan 16, 2026

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 (2 comments) (1 reaction) (2 assignees)TypeScript (48,455 stars) (6,726 forks)batch import
BugDomain: CrashesFix AvailableHelp Wanted

Description

🔎 Search Terms

addTypesToUnion stack overflow

getUnionTypeWorker crash

keyof missing type crash

Internal Compiler Error destructuring

🕗 Version & Regression Information

v5.7.3 / v5.8.3 / v5.9.3 / Nightly: Crashes（This crash only occurs when the --strict flag is enabled.）

⏯ Playground Link

https://www.typescriptlang.org/zh/play/?target=7&ts=6.0.0-dev.20260115#code/MYewdgzgLgBA3jYAaGATFBTFAzFBzGAXwC4YBrDATxGxhgF54AoOugOg7hdZ47a56DWfAULF1gpAAxJu4uoVnzWqaXMGL1PDGp6ae2JoQDcQA

💻 Code

const { c, d, e, f, g }: keyof  = {
    ...{
        ...{
            ...{
                c: 0,
            },
            d: 0
        },
        e: 0
    },
    f
};

🙁 Actual behavior

 .\ts-versions\nightly\node_modules\.bin\tsc.cmd --strict  .\mutated\destructuringSpread_mutated_batch15.ts
D:\do\typeFuzz\ts-versions\nightly\node_modules\typescript\lib\_tsc.js:123166
      throw e;
      ^

RangeError: Maximum call stack size exceeded
    at addTypesToUnion (D:\do\typeFuzz\ts-versions\nightly\node_modules\typescript\lib\_tsc.js:61209:27)                                                                                                 
    at getUnionTypeWorker (D:\do\typeFuzz\ts-versions\nightly\node_modules\typescript\lib\_tsc.js:61385:22)                                                                                              
    at getUnionType (D:\do\typeFuzz\ts-versions\nightly\node_modules\typescript\lib\_tsc.js:61381:12)                                                                                                    
    at mapType (D:\do\typeFuzz\ts-versions\nightly\node_modules\typescript\lib\_tsc.js:69885:37)                                                                                                         
    at getApparentTypeOfContextualType (D:\do\typeFuzz\ts-versions\nightly\node_modules\typescript\lib\_tsc.js:73263:28)                                                                                 
    at checkObjectLiteral (D:\do\typeFuzz\ts-versions\nightly\node_modules\typescript\lib\_tsc.js:73978:28)                                                                                              
    at checkExpressionWorker (D:\do\typeFuzz\ts-versions\nightly\node_modules\typescript\lib\_tsc.js:80883:16)                                                                                           
    at checkExpression (D:\do\typeFuzz\ts-versions\nightly\node_modules\typescript\lib\_tsc.js:80794:32)                                                                                                 
    at checkObjectLiteral (D:\do\typeFuzz\ts-versions\nightly\node_modules\typescript\lib\_tsc.js:74062:37)                                                                                              
    at checkExpressionWorker (D:\do\typeFuzz\ts-versions\nightly\node_modules\typescript\lib\_tsc.js:80883:16)                                                                                           

Node.js v22.19.0

🙂 Expected behavior

The compiler should report a syntax error and not crash.

Additional information about the issue

No response

Contributor guide

Tech stack
typescript
Domain
backendtooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
5
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
over 1 week
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
understanding of TypeScript type systemfamiliarity with object destructuringknowledge of keyof operator
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
10
Research direction
The issue is a stack overflow crash in the TypeScript compiler when using an incomplete `keyof` type annotation on object destructuring. The stack trace points to `addTypesToUnion` and `getUnionTypeWorker` functions in `src/compiler/checker.ts`. Investigate how the compiler handles missing type arguments after `keyof` in object destructuring patterns, and ensure a proper syntax error is reported instead of crashing. The fix likely involves adding a type validity check before processing the `keyof` type expression in the destructuring context.