Parser Idempotency issue: braces added every time after each pass

[MahnurA]

Describe the bug
Starting and ending braces are added within an empty code block.

To Reproduce

This javascript

with (this) {{
}}

is transformed to the following, after passing through the parser:

with (this) {{
    {
    }
}}

And then to below, after another pass through:

with (this) {{
    {
        {
        }
    }
}}

Expected behavior
Multiple runs through the parser should result in the same output.

Build environment (please complete the following information):

• OS: Ubuntu
• Version: 20.04
• Target triple: x86_64-unknown-linux-gnu
• Rustc version: rustc 1.70.0

Additional context
Found by #4822

[veera-sivarajan]

Hi, I'd like to work on this.

[jedel1043]

@veera-sivarajan Assigned!

[veera-sivarajan]

@MahnurA Can you please let me know the command that shows the transformed code? I tried cargo run -- test.js --dump-ast json-pretty with the given input but did not see any difference in the output.

[MahnurA]

@veera-sivarajan I used the fuzzer to discover the bug, specifically the parser-idempotency fuzzer. However after #3059 was merged the fuzzers can't run anymore (not sure what broke but will be fixed soon), but you should still be able to run the previous version and see.

[addisoncrump]

I can confirm that this is still present.