Macro import paths with Windows separators are ignored

[haltcase]

• babel-plugin-macros version: 2.6.1
• node version: 12.6.0
• npm (or yarn) version: yarn 1.16.0

Relevant code or config

import { _ } from '.\\macro'
import { it } from 'E:\\dev\\param.macro\\macro'

I came across this when testing param.macro and have noticed that tests will fail on Windows — the import path I generate for testing (an absolute Windows style path) is ignored by babel-plugin-macros but is also further incompatible with it.

What you did:

Compile

What happened:

The macro is not activated.

Reproduction repository:

1. git clone https://github.com/citycide/bpm-repro.git
2. yarn
3. yarn build
4. dist.js is created but was not transformed

Problem description:

1. the macro regex only accounts for a unix path separator (/)
2. even once 1) is fixed, the resolve module throws MODULE_NOT_FOUND

Suggested solution:

First the regex would need to be updated to something like this:

https://github.com/kentcdodds/babel-plugin-macros/blob/2d57c60adadd8904db9624614faffc34a251c40d/src/index.js#L5

- const macrosRegex = /[./]macro(\.js)?$/
+ const macrosRegex = /[./\\]macro(\.js)?$/

However this isn't enough as once applyMacros is actually called, the resolve module will throw:

Error: Cannot find module '.\macro' from 'E:\dev\param.macro'

---

There are existing issues that mention Windows but they all relate to tests.

[kentcdodds]

Hi @citycide,

I didn't realize that you could do a path like that. Is that permissible according to the ES spec?

[haltcase]

It's possible that it's not allowed in import sources and that it has to be a valid URI. node's require on the other hand is simply given a path and a Windows path is perfectly valid.

I could generate a require instead but this would still not work, and then we need to decide if we're going to separate the source handling logic to follow the differing specs of import and require.

[sompylasar]

the import path I generate for testing (an absolute Windows style path)

Some people are genuinely curious why you need Windows paths.

https://twitter.com/rossipedia/status/1148984649735000064

[rossipedia]

I just realized that I'm assuming that absolute Windows paths are not supported by the ES spec, but I could be completely wrong about that. Would replacing the \\ separator with / work?

i.e. change 'E:\\dev\\param.macro\\macro' to 'E:/dev/param.macro/macro'

[rossipedia]

So, I'm not sure if they're supported by the ES spec, but it looks as though they're not supported by Node:

[kentcdodds]

Alright. I'll go ahead and close this one then 👍 Thanks!

[resynth1943]

Sorry for asking here, @rossipedia, but what is that font?

[haltcase]

@sompylasar I don't necessarily. I was just using Node's path.join and process.cwd to generate the path during testing, and on Windows those paths make everything broken. I guess I can unixify everything but that went against my cross-platform instincts. :laughing:

@rossipedia that's odd because I was able to run a very similar example and a Windows path worked just fine.

[sompylasar]

I believe Node.js source can be considered a reference implementation.

It says that the thing you put in the import statement is called "module_request" (which not necessarily maps to a file system path 1:1). https://github.com/nodejs/node/blob/2983eaca84e9e79c19dba09fb036fe55131b8a5d/deps/v8/src/ast/modules.h#L37

It goes to GetModuleNamespace which is an abstract ECMAScript operation https://github.com/nodejs/node/blob/8aca934009225b30bff7d7927d2eb9f667dbff9f/deps/v8/src/runtime/runtime-module.cc#L38

https://tc39.es/ecma262/#sec-getmodulenamespace

That mentions the HostResolveImportedModule abstract operation which depends on the implementation of the host environment.

So the answer is actually "the spec says it depends on the host environment".

[kentcdodds]

the spec says it depends on the host environment

😬 I didn't vote for that, lol

[sokra]

If the host environment is webpack, absolute windows paths are allowed. Relative paths with windows separator are not.

[kentcdodds]

I personally don't think it's worthwhile supporting this, but because it's so easy to do so (update the regex) I'm actually fine if someone wants to make a PR for it.

[rossipedia]

@resynth1943 no problem! it's Victor Mono