Uniform line endings for multi line strings/comments

[sidharthv96]

Fixes #6501

• Removed double parsing of the doc
• Moved newline check to printDocToString

• I’ve added tests to confirm my change works.
• (If the change is user-facing) I’ve added my changes to changelog_unreleased/*/pr-XXXX.md file following changelog_unreleased/TEMPLATE.md.
• I’ve read the contributing guidelines.

✨Try the playground for this PR✨

[sidharthv96]

Updated the test case to original code from #6501

[j-f1]

How does this work with e.g. template strings containing LFs? Does it preserve them or does it change their content?

[sidharthv96]

console.log(
        `Multiline \n string\
         Multiline string\
         Multiline string`
      );

Will have the \n preserved (As they are escaped in the text representation). This only changes the actual line endings in the file.

I've updated the test case to cover this.

[sidharthv96]

@thorn0 any pointers on how to handle the codecov failure?

[thorn0]

@sidharthv96 Failing because of "+-0.01%" looks like a misconfiguration. Ignore it.

[thorn0]

@j-f1 I think your question was about non-escaped line breaks in template literals. So I did a little research. Turns out (see the spec) template literals treat any LineTerminatorSequence as LF, no matter how it's represented in the source code:

In other words, eval("`\r`") === '\n'. This means it's totally safe to convert line endings in source files. Prettier's correctness goal isn't compromised.

[thorn0]

@sidharthv96 Thanks for fixing this!