camelcase duplicate warning bug

[helixbass]

Tell us about your environment

• ESLint Version: 5.4.0
• Node Version: 8.11.3
• npm Version: 5.6.0

What parser (default, Babel-ESLint, etc.) are you using?
Coffeescript (ran into this while working on eslint-plugin-coffee)

Please show your full configuration:

The relevant configuration would be camelcase: error. I encountered this while testing the Coffeescript custom parser against the existing ESLint lib/rules/camelcase.js rule

What did you do? Please include the actual source code causing the issue, as well as the command that you used to run ESLint.

I was running against a copied version of tests/lib/rules/camelcase.js where the tested pieces of code were converted to Coffeescript, but these are the corresponding tests in tests/lib/rules/camelcase.js that would have been failing:

• invalid test var { category_id } = query; (where ignoreDestructuring is implicitly false)
• invalid test function foo({ no_camelcased }) {}; (where ignoreDestructuring is implicitly false)

What did you expect to happen?
For these tests to pass

What actually happened? Please include the actual, raw output from ESLint.
They failed due to reporting 2 errors instead of the expected one. I found the bug and will open a fixing PR momentarily

[ilyavolodin]

Sounds like a bug. But I can't seem to reproduce it in the online demo: https://eslint.org/demo/#eyJ0ZXh0IjoiLyplc2xpbnQgY2FtZWxjYXNlOiBbXCJlcnJvclwiLCB7aWdub3JlRGVzdHJ1Y3R1cmluZzogZmFsc2V9XSovXG5cbnZhciB7IGNhdGVnb3J5X2lkIH0gPSBxdWVyeTsiLCJvcHRpb25zIjp7InBhcnNlck9wdGlvbnMiOnsiZWNtYVZlcnNpb24iOjksInNvdXJjZVR5cGUiOiJzY3JpcHQiLCJlY21hRmVhdHVyZXMiOnt9fSwicnVsZXMiOnt9LCJlbnYiOnt9fX0=

[helixbass]

@ilyavolodin try:
https://eslint.org/demo/#eyJ0ZXh0IjoiLyplc2xpbnQgY2FtZWxjYXNlOiBbXCJlcnJvclwiLCB7aWdub3JlRGVzdHJ1Y3R1cmluZzogZmFsc2V9XSovXG5cbnZhciB7IGNhdGVnb3J5X2lkOiBjYXRlZ29yeV9pZCB9ID0gcXVlcnk7Iiwib3B0aW9ucyI6eyJwYXJzZXJPcHRpb25zIjp7ImVjbWFWZXJzaW9uIjo5LCJzb3VyY2VUeXBlIjoic2NyaXB0IiwiZWNtYUZlYXR1cmVzIjp7fX0sInJ1bGVzIjp7fSwiZW52Ijp7fX19

With a different parser that doesn't reuse the same Identifier object for shorthand key and value, the demo you shared would also produce duplicate warnings

[ilyavolodin]

Got it, thanks for the explanation.