2
There are some potential issues. These are the main ones:
1) Since we expose Smarty directly, the BC layer for v2 would be required. It is good, but not 100% perfect. Alone, this would probably not be a blocker, but it could break previously working code.
2) Due to changes in parsing, things as simple as extra spaces or missing quotes may cause unintended results or errors in some circumstances. These were harmless in v2.
3) Many XOOPS templates have historically relied on an unassigned variable to evaluate as false. While this may still work, it will produce error messages, sometimes in log file filling quantities..
The code and templates included in XOOPS and the more actively maintained modules have some of these possible errors corrected already. There are, however more modules, and even more templates and themes that may never have been checked. Those are the ones that may break sites which have worked for years on upgrading.
With the 2.5 series, we want to encourage upgrades especially for security reasons. Adding features we suspect may cause issues is something we want to avoid if at all possible. The next generation XOOPS will include the latest Smarty, and as a major upgrade, the BC issues will be expected, acceptable and documented.
