[Bug]: true `ignoreBrowserslistConfig` but reading `.browserslistrc`

💻

• Would you like to work on a fix?

How are you using Babel?

@babel/cli

Input code

$ strace -f -e file -o file.log babel --config-file ./babel.config.json example.mjs

Configuration file name

babel.config.json

Configuration

{
  "presets": [
    [
      "@babel/preset-env",
      {
        "debug": true,
        "ignoreBrowserslistConfig": true,
        "targets": {
          "chrome": "92"
        }
      }
    ]
  ]
}

Current and expected behavior

Actual

$ grep -F .browserslist file.log && echo FAIL || echo OK
... access("/path/to/cwd/browserslist", F_OK) = -1 ENOENT (No such file or directory)
... access("/path/to/cwd/.browserslistrc", F_OK) = -1 ENOENT (No such file or directory)
... access("/path/to/cwd/browserslist-stats.json", F_OK) = -1 ENOENT (No such file or directory)
... access("/path/to/browserslist-stats.json", F_OK) = -1 ENOENT (No such file or directory)
... access("/path/browserslist-stats.json", F_OK) = -1 ENOENT (No such file or directory)
... access("/browserslist-stats.json", F_OK) = -1 ENOENT (No such file or directory)
FAIL

Expected

$ grep -F .browserslist file.log && echo FAIL || echo OK
OK

Environment

@babel/preset-env: ^7.15.6 => 7.15.6

Possible solution

No response

Additional context

Not a real world use case

Just try to analyze filesystem footprint, to solve another config problem by another build tool .

Found babel have this footprint, even set ignoreBrowserslistConfig to false.

[loynoir]

https://github.com/loynoir/reproduce-babel-13780.js

[JLHwung]

The current behaviour is expected:

• preset-env does not load .browserslistrc as instructed by ignoreBrowserslistConfig: true. Actually since you have specified targets, you can safely remove ignoreBrowserslistConfig.
• @babel/core loads .browserslistrc because the top level targets option is not provided. Note that @babel/core is unaware of preset-env, so it tries to load the browserslist config, in order to determine a global targets information that can be respected by all plugins/presets.

In your case, if you migrate targets in preset-env to top level, Babel will not load browserslistrc.

{
  "targets": {
    "chrome": "92"
  },
  "presets": [
    [
      "@babel/preset-env",
      {
        "debug": true,
      }
    ]
  ]
}