See #13350. The current Meson formatter removed some trailing commas on shorter lists. However there is a workaround:

This can be manually worked around by adding a placeholder comment.

In particular, if one does

foo(
  bar,
  baz,
  # comment
)

this can't become

foo(bar, baz, # comment)

because that means something else.

I would prefer this as it will reduce churn as files are added and removed. I made an upstream issue for this: mesonbuild/meson#14721. This workaround would hopefully be just a stop-gap until we have a proper solution.

Originally posted by @Ericson2314 in #13350 (comment)