|mediawiki/core||master||+4 -0||Show a warning in edit preview when a template loop is detected|
|Resolved||matej_suchanek||T162149 Show a warning about template loops in edit preview|
|Resolved||matej_suchanek||T160743 Add tracking category when a template loop is detected|
The page itself is transcluded inside #expr, the error message is not shown. Have seen the same an dewiki, where the template transclusion was part of a #ifeq and therefor the text was not shown. Was hard to find the issue.
I do not know if it is a new problem or an issue we had for months. I just noticed it today. I understood template loops in the days of just templates. Now many templates are Lua based. What lua related conditions have to be met to trigger addition of this category? Are there any ways to figure out what triggers it?
I just noticed that c:Template:LangSwitch is included, and last Friday I made very large change to c:Module:Fallback: removing many frame:preprocess calls and switching to use standard MediaWiki fallback chain instead of commons-only fallback chain. Would some changes there trigger it?
Earliest date seem to be from 2017-09-08, the day I changed Module:Fallback, and Template:LangSwitch only uses that module. So most likely that code is the problem. The code is also very simple now. Anything there that looks like might be causing the issue?
Whatever the issue with Commons's 'Creator' template is, it's not really related to this task (other than the new error message possibly making it easier to find the problem). The code will go live this week per the usual schedule, it should be deployed to Commons on Wednesday.
(As a side note, when looking into this, I found a fascinating Chrome bug that affects the rendering of Template:Creator on Commons: https://bugs.chromium.org/p/chromium/issues/detail?id=764031)