Same hash generated for two different functions with similar names

[JustinLloyd]

🐛 bug report

During a production build Parcel or possibly Terser generates the same function hash for two different functions:

I have created a project using Parcel that includes jquery, gsap and pixi.js as dependencies. A development build works as expected, but a production build generates the same function hash for two different, but similarly named functions:
These two functions:

$parcel$export($a43a28938b26b986$exports, "hex2rgb", () => $a43a28938b26b986$export$9b426722ac942144);
$parcel$export($a43a28938b26b986$exports, "rgb2hex", () => $a43a28938b26b986$export$9b426722ac942144);

These two functions are part of pixi.js.

/**
 * Converts a hexadecimal color number to an [R, G, B] array of normalized floats (numbers from 0.0 to 1.0).
 *
 * @example
 * PIXI.utils.hex2rgb(0xffffff); // returns [1, 1, 1]
 * @memberof PIXI.utils
 * @function hex2rgb
 * @param {number} hex - The hexadecimal number to convert
 * @param  {number[]} [out=[]] - If supplied, this array will be used rather than returning a new one
 * @return {number[]} An array representing the [R, G, B] of the color where all values are floats.
 */ function $a43a28938b26b986$export$9b426722ac942144(hex, out) {
    if (out === void 0) out = [];
    out[0] = (hex >> 16 & 255) / 255;
    out[1] = (hex >> 8 & 255) / 255;
    out[2] = (hex & 255) / 255;
    return out;
}

/**
 * Converts a color as an [R, G, B] array of normalized floats to a hexadecimal number.
 *
 * @example
 * PIXI.utils.rgb2hex([1, 1, 1]); // returns 0xffffff
 * @memberof PIXI.utils
 * @function rgb2hex
 * @param {number[]} rgb - Array of numbers where all values are normalized floats from 0.0 to 1.0.
 * @return {number} Number in hexadecimal.
 */ function $a43a28938b26b986$export$9b426722ac942144(rgb) {
    return (rgb[0] * 255 << 16) + (rgb[1] * 255 << 8) + (rgb[2] * 255 | 0);
}

Which as you can see are clearly different, with different signatures, but it seems a hash collision occurs on the names: hex2rgb and rgb2hex.

🤔 Expected Behavior

Generate different hash based on different functions.

😯 Current Behavior

Generates the same hash based on different functions.

This is the error I get in the browser when loading the code:

11:15:58.100 Uncaught SyntaxError: redeclaration of function
$a43a28938b26b986$export$9b426722ac942144invaders.1fffc83b.js:10983:13
note: Previously declared at line 10932, column 13invaders.1fffc83b.js:10932:13

💁 Possible Solution

Conflict occurs during hash of function name. Suggestion would be to hash on the function and signature, or add some randomization to the hash.

🔦 Context

Cannot produce a working production build when including pixi.js as part of the bundle.

💻 Code Sample

🌍 Your Environment

Software	Version(s)
Parcel	2.0.0-rc.0
terser	5.7.1
Node	13.9.0
npm/Yarn	6.13.7
Operating System	Windows 10 Pro for Workstations

EDIT: Fixed typo.

[mischnic]

Can be reproduced with

// index.js
import * as x from "./x.js";
console.log(x);

// x.js
export function hex2rgb() {
    return "hex2rgb";
}

export function rgb2hex() {
    return "rgb2hex";
}

At least in this simple example, it's not a collision of the Rust hashing function that's used for that (but I don't know why I'm not getting the hash that Parcel outputs in the bundle)

use std::collections::hash_map::DefaultHasher;
use std::hash::{Hash, Hasher};

macro_rules! hash {
    ($str:expr) => {{
        let mut hasher = DefaultHasher::new();
        $str.hash(&mut hasher);
        hasher.finish()
    }};
}

fn main() {
    let str1 = "hex2rgb";
    let str2 = "rgb2hex";
    println!("{:x}", hash!(str1)); // dc42ded1fdd0428a
    println!("{:x}", hash!(str2)); // 8b15b4e588fd1a8
}

parcel/packages/transformers/js/core/src/hoist.rs

Line 1038 in 7c4d267

format!("${}$export${:x}", self.module_id, hash!(exported)).into()

[beepboopitschloe]

seeing this as well on v2.0.0-rc0 with the same input (pixi.js).

[devongovett]

I believe this is caused by servo/string-cache#224