Error reported for negative indexed location tracking references, e.g. `@-1`

[GerHobbelt]

bison+jison-gho support $n for n <= 0:

Quoting the bison manual at https://www.gnu.org/software/bison/manual/html_node/Actions.html (bold emphasis mine):

$n with n zero or negative is allowed for reference to tokens and groupings on the stack before those that match the current rule. This is a very risky practice, and to use it reliably you must be certain of the context in which the rule is applied. Here is a case in which you can use this reliably:

foo:
  expr bar '+' expr  { … }
| expr bar '-' expr  { … }
;
bar:
  %empty    { previous_expr = $0; }
;

As long as bar is used only in the fashion shown here, $0 always refers to the expr which precedes bar in the definition of foo.

As bison/jison/jison-gho support location references as well, format @n or @label, the above implies @-1 is a legal location ref.

That FAILS since 0.6.0-??? when we switched to parsing / validating action code chunks via a patched recast library: https://github.com/GerHobbelt/recast :: https://www.npmjs.com/package/@gerhobbelt/recast which recognizes all jison-gho supported reference types: $n, @n, #n, ##n, #label#... but still barfs on @-1.

Note

Given this, I expect my patched recast/esprima also barfs on #-1 and ##-1...

[GerHobbelt]

Observed while checking out #28 + #27.