Reac isCompatTag validator accepts leading dash '-'

[claudiopro]

Choose one: is this a bug report or feature request? Bug report

The React isCompatTag accepts a leading dash '-' in tag names. This means it will accept JSX tag names like <-div>.

Input Code

Adding a test suite for the React isCompatTag validator:

  suite("isCompatTag", function() {
    it("rejects leading dash '-'", function() {
      assert(t.react.isCompatTag("-div") === false);
      assert(t.react.isCompatTag("-span") === false);
      assert(t.react.isCompatTag("-a") === false);
      assert(t.react.isCompatTag("-input") === false);
    });
  });

Produces this error:

  7752 passing (2m)
  94 pending
  1 failing

  1)  rejects leading dash '-':

      AssertionError [ERR_ASSERTION]: false == true
      + expected - actual

      -false
      +true

      at Context.<anonymous> (packages/babel-types/test/validators.js:58:7)

Babel/Babylon Configuration (.babelrc, package.json, cli command)

N/A, reproduced in unit tests

Expected Behavior

Tag names with leading dash characters '-' are not valid

Current Behavior

Tag names with leading dash characters '-' are accepted

Possible Solution

Fix this regexp:

https://github.com/babel/babel/blob/master/packages/babel-types/src/validators/react/isCompatTag.js#L3

Context

Spotted in @hzoo's tweet: https://twitter.com/left_pad/status/949301094903099393

Your Environment

software	version(s)
Babel
Babylon
node
npm
Operating System

[babel-bot]

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[claudiopro]

Preparing a fix