Quote inside of RegExp breaks cleanString

[kherock]

Describe the bug

Plugins that use the emptyString() function have a serious issue when they're activated while the raw code has a RegExp expression with a single or double quote inside.

test('strings', () => {
  const clean = emptyString(`
    // comment1
    const a = 'aaaa'
    /* coment2 */
    const b = "bbbb"
    const regexp = /'/
    const c = "cccc"
    // '
    /*
      // coment3
    */
    /* // coment3 */
    // comment 4 /* comment 5 */
  `)
  expect(clean).toMatch("const a = '\0\0\0\0'")
  expect(clean).toMatch('const b = "\0\0\0\0"')
  expect(clean).toMatch('const c = "\0\0\0\0"')
})

In this test, the entire const c assignment is clobbered over with null characters due to the single quotes surrounding it in the RegExp and in the comment. In cases where the "matching" single quote occurs in the middle of a statement, major parsing errors occur and the whole build can fail.

Reproduction

I'm having trouble isolating this in vite.new, but it's fairly straightforward to reproduce in the unit test file. I can work on providing a repo if it's absolutely necessary.

System Info

System:
    OS: macOS 11.6
    CPU: (12) x64 Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
    Memory: 55.61 MB / 16.00 GB
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 16.14.2 - /usr/local/bin/node
    Yarn: 3.2.0 - /usr/local/bin/yarn
    npm: 8.5.0 - /usr/local/bin/npm
  Browsers:
    Chrome: 100.0.4896.127
    Edge: 100.0.1185.44
    Firefox: 99.0.1
    Safari: 15.0

Used Package Manager

pnpm

Logs

● strings

    expect(received).toMatch(expected)

    Expected substring: "const c = \"\""
    Received string:    "················
        const a = ''··················
        const b = \"\"
        const regexp = /''·····················································································
      "

      35 |   expect(clean).toMatch("const a = '\0\0\0\0'")
      36 |   expect(clean).toMatch('const b = "\0\0\0\0"')
    > 37 |   expect(clean).toMatch('const c = "\0\0\0\0"')
         |                 ^
      38 | })
      39 |
      40 | test('strings comment nested', () => {

      at Object.<anonymous> (packages/vite/src/node/__tests__/cleanString.spec.ts:37:17)

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to https://github.com/vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[poyoho]

appear in this ?

const regexp = /'/ 
const c = "cccc" 

[kherock]

@poyoho the single quote on the next line is important:

const regexp = /'/ 
const c = "cccc" 
// '

You can yield syntax errors if the quote is actually used in code later

const regexp = /'/ 
const c = "cccc" 
const str = "It's broken!"

emptyString transforms the above into

const regexp = /''s broken!\"

[poyoho]

very thank for your report. would you had a time help me to test #7871 ?