Rule "no-unused-variable" fails to trigger in unused recursive functions

[lcrespom]

Bug Report

Rule no-unused-variable fails to trigger in unused recursive functions.

• TSLint version: 4.1.1
• TypeScript version: 2.1.4
• Running TSLint via: VS Code + TSLint extension v0.7.1.

TypeScript code being linted

// Example: typical recursive function
function factorial(x) {
    if ( x > 1)
        return x * factorial(x - 1);
    return 1;
}

with tslint.json configuration:

    "no-unused-variable": true

Actual behavior

No lint error / warning is generated even if factorial is never used.

Expected behavior

An error should be generated if factorial is never used, but because it is used by itself, the linter incorrectly assumes it is already being used.

[andy-hanson]

Since this uses the TypeScript implementatino now (#2235), you should file a bug with TypeScript.