The expression /=/ does not get parsed as a regexp

[lxhom]

Describe the bug
The expression /=/ does not get parsed as a regexp

To Reproduce

let myRegex = /=/;

That throws this: "unexpected token '/=', primary expression at line 1, col 15"

Expected behavior
It should give me the regular expression for a single =. A workaround I used is just using /.{0}=/, but this should work without it.

Build environment (please complete the following information):

(tested it on my machine and on the playground)

• OS: Windows & Boa Playground
• Version: 0.15.0 & the playground doesn't tell me
• Target triple: x86_64-pc-windows-msvc & idk
• Rustc version: rustc 1.63.0-nightly (7466d5492 2022-06-08)

[Razican]

For anyone willing to tackle this, the / token lexing happens here: https://github.com/boa-dev/boa/blob/main/boa_engine/src/syntax/lexer/mod.rs#L128-L187

This checks if the / token is the beginning of a comment (when it's followed by / or *), and if not, it will check the current lexer goal symbol. This is set by the parser, depending on what we're trying to parse.

There are some places where a / will only mean a division element, and others when it can only be a regular expression start. In this case, it seems it goes through the first branch (InputElement::Div | InputElement::TemplateTail), since it will check if the next character is an equal sign (which it is), and then say that we are getting a Punctuator::AssignDiv symbol.

The parser then is surprised, since the assign punctuator already appeared, and therefore, you cannot use the /= symbol.

It seems, that the issue here is that the parser is not properly setting the goal symbol. Once the let myRegex = has been consumed, the goal symbol should not accept the division operation, only the regular expression.

You should be able to follow the documentation in our debugging section to track the issue down, but feel free to ask questions on this.