Is this safe? Whilematch x is invalid,match (x) should be a function call.

Hummmm, that's a good point. ifmatch(x) is by itself this will probably fail. Let me think how can we workaround that

I will add also a test for that case

Fixed in the last ammend

For my own understanding... does double-ampersand raise aSyntaxError at that token's location suggesting it if it doesn't exist? That's really nice.

For my own understanding... does double-ampersand raise aSyntaxError at that token's location suggesting it if it doesn't exist? That's really nice.

Yeah, is a "forced token" operator. Notice that it also hard-stops the parsing: no other alternative will be considered.

I don't understand why e.g.match(1) doesn't reachinvalid_match_stmt, so I'm still concerned.

Theinvalid_* rules are now only checked in a second pass of the parser if the first one fails. This was done mainly for speed, but allows to introduce these kind of error messages with early failures.

Doesinvalid_match still need to be guarded withCHECK_VERSION?

Doesinvalid_match still need to be guarded withCHECK_VERSION?

Not really because is a syntax error, but it certainly won't hurt.