bug#27525: 25.1; Line wrapping of bidi paragraphs

[Itai Berli]

I'd also like to add what should be obvious (considering the fact the Emacs provides a line wrapping feature to begin with) that the "remedy" of braking long lines by inserting newline character is not very usable, as one would have to move the newlines to other locations if one had to add a few more words to the line.

On Tue, Jul 4, 2017 at 12:11 PM, Itai Berli <itai.berli@gmail.com> wrote:

I obviously didn't end up replacing the bullet points by numbers...

On Tue, Jul 4, 2017 at 12:10 PM, Itai Berli <itai.berli@gmail.com> wrote:

I'd like to add that this behavior breaks the Unicode bidirectional algorithm (UBA), and hence invalidates Emacs' claim of full conformance, or indeed of weak conformance, for that matter (so-called 'implicit bidirectionality' -- see section 4.2 of the UBA specifications).

The reason is that section 3.4 'Reordering Resolved Levels' of the algorithm states (I replaced the bullet points in the original by numbers):

> * The characters are shaped into glyphs [...]

> * The accumulated widths of those glyphs (in logical order) are used to determine line breaks.

The Emacs line-wrapping algorithm does not use the logical order of the glyphs to determine line breaks, as evidence by the example given in my original post, which I shall link to again: http://imgur.com/Bckn7zP