Suggest --fixed-strings on invalid regexps

[Wilfred]

$ rg "foo("
Error parsing regex near 'foo(' at character offset 3: Unclosed parenthesis.

I think ripgrep should suggest the --fixed-strings argument if there's a regex syntax error.

[BurntSushi]

Hmmmm... I think I'd be OK with that.

[balajisivaraman]

I can pick this one up next.

One question though: Do we still want the error generated by the regex lib to be propagated all the way to the command line? Or are OK with replacing that with a generic error such as: "Syntax error encountered while parsing provided regex. Please recheck. Note: Perhaps you meant to use --fixed-strings instead."

I can think of a relatively straightforward, easy-to-implement fix if we're OK with the latter.

[erikrw]

I would suggest regex error details to be shown to the user. grep, ack, and ag also give details about regex errors.

[BurntSushi]

@balajisivaraman We definitely want to surface the syntax error.

[balajisivaraman]

Can this be closed with the merging of #727?

[BurntSushi]

@balajisivaraman Yup! Thanks.

[wsdjeg]

@BurntSushi does --fixed-strings means auto fixe regex? I mean if the regex has no errors, just use it as regex.

[BurntSushi]

@wsdjeg I don't understand your question or your suggestion. Could you please elaborate? Please include examples.

[BurntSushi]

@wsdjeg Also, have you read the documentation?

    -F, --fixed-strings                     
            Treat the pattern as a literal string instead of a regular expression. When this flag is
            used, special regular expression meta characters such as (){}*+. do not need to be
            escaped.

[wsdjeg]

@BurntSushi I have read it, I just create a grep plugin , and using rg as backgroud tool. search the user's input.

I hope I auto detect if the user is input a right expression. that means, it will be better there is an option --auto-fixed-string. if there is error in such expression, treat it as fixed string. otherwise use it as regex.

here is an gif:

[BurntSushi]

@wsdjeg That seems like a distinct feature request that is completely orthogonal to this issue. Please open a new issue.

[wsdjeg]

Ok, and thanks for this project.