Regression in v0.14.x

[btd]

Hi,
thank you for great project it really moved community forward. I caught bug in v0.14 (using vite)
If it is was reported sorry i did not found it.

there is repro repo https://github.com/btd/esbuild-bug

[hyrious]

Because you have type: module in package.json, esbuild produces codes that follows the node behavior (https://esbuild.github.io/content-types/#default-interop). In which case you can only do import default_name from "some-cjs-module".

Looks like esbuild drops one pure variable declaration (see it live):

// input
var A = {} // this is pure
A.x = 1
var A = {}
A.y = 2

// output
A.x = 1;
var A = {};
A.y = 2;

Now question: is var A = A || {} pure? It seems esbuild marks all of them as pure.

However, if you manually give it some sife effects, esbuild won't erase it (see it live):

// input
var A = {} // this is pure
A.x = 1
var A = console.log(1) || {} // not pure
A.y = 2
var A = A || {} // pure again
A.y = 3
var A = {} // keep last one
A.y = 4

// output
A.x = 1;
var A = console.log(1) || {};
A.y = 2;
A.y = 3;
var A = {};
A.y = 4;

[magic-akari]

There are two variable declarations in gradient-parser.
The first declarations disappears after esbuild compilation.

https://github.com/rafaelcaricio/gradient-parser/blob/92b6e8011e02e3682064fd2aea20da6becf3347e/build/node.js#L5
https://github.com/rafaelcaricio/gradient-parser/blob/92b6e8011e02e3682064fd2aea20da6becf3347e/build/node.js#L172