microsoft / microsoft/TypeScript

Uncalled Function Checks don't check negative condition

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#34,815 4 comments 8 reactions 0 assignees View on GitHub

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Description

function foo() {
}

if (!foo) {
    let x = 10
}
else {
}

Expected: Error on !foo that the condition is always true because foo is defined.
Actual: No error.

Also, any work on this should include the following test:

function foo() {

}

if (!foo) {
}
else {
    foo()
}

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with TypeScript's uncalled-function checks and reproduce the issue using the provided snippets. Add coverage for both the negative condition and the supplied else branch, and consider it done when the !foo condition is reported as always true.

Written by the indexing model from the issue text.

Assessment

Tech stack
typescript
Domain
compilers
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
38/100

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