Metavariable-regex is anchored

[nbrahms]

Per docs, this should be unanchored:

https://semgrep.dev/s/KgRY

[r2c-demo]

This issue is synced in Linear at https://linear.app/r2c/issue/PA-980/metavariable-regex-is-left-anchored.

[aryx]

@mjambon can we close this issue?

[mjambon]

@aryx no, I didn't touch that. I wasn't aware of this bug. For example, the pattern a should match xxa but currently, it doesn't. The issue is apparently that the regexp is matched at the beginning of the string using something like Pcre.pmatch instead of being matched successively at all the positions in the string using the appropriate function.