[mathiasrw]

Closes #816

Stacked on #832.

Change

The names of named groups were only found when they were ASCII ([A-Za-z_$][\w$]*). So with (?<año>\d) and rr_año in the code, RexReplace did not see that the code uses a group, ran it once per file where the groups are not there, and it failed with ReferenceError.

Now a name is found with the same rule as a name in javascript: \p{ID_Start} and \p{ID_Continue}.

> echo -n a1b2 | rexreplace '(?<日>\d)' 'rr_日 * 2' --js
a2b4

The panic for a name that ends with _ (#825) works for these names too.

Tests

test/fix/816.test.js is new, and fails without the fix. yarn test-ci passes.

From the review of 23 October.

After the review of 24 October

• The names of the groups are read from the compiled regex, and not by scanning the pattern. So text that only looks like a group, like \(?<a_>b or [(?<a_>], is not one, and is no longer a panic (from the review of Access named groups from --js code to close #825 #832). It also works for any name javascript allows.
• rr_year_ on its own is now seen as a use of the group. Before, rr_year_ + "|" gave ReferenceError: rr_year_ is not defined, an old bug from Give --js code the named groups to close #799 #806 on the same line.

Follow-up

test/fix/816.test.js also shows the code for the odd names: rr_año_ (the space cousin), rr_𝒜 (outside the BMP, the reason for the u flag), rr_$é, rr_Æble and rr_x٣, and that rr_rr_year is not the group year. 10 of 11 fail without the fix.