#4725 tex-array creates invalid double subscript

[Leo Butler]

tex-array is used to implement the (terrible, in my opinion) dwim subscripting and to typeset array arguments as subscripts. This produces invalid TeX:

tex(a_1[4]);
$$a_{1}_{4}$$

or

tex(a1[4]);
$$a_{1}_{4}$$

There are at least two alternatives:

1. Wrap the output of tex-array in brace brackets. That would produce valid TeX like {{a_{1}}_{4}} in both cases.
2. Add a switch to disable dwim subscripting. This would also produce valid TeX (like {\it a\_1}_{4} or {\it a1}_{4})

Attached is a patch that implements both (but only does 1. when dwim subscripting is active).

This bug was first observed in bug #4696.

[Leo Butler]

Patch.

[Robert Dodier]

For the record, I also think the DWIM inferred subscript stuff is terrible. That said, I think (1) is better than what we have now (and also preferable to (2)).