Snow and ice remain below tree leaves which generate into existing chunks

The Bug

When terrain is being generated, sometimes snow will generate under trees instead of on top of them.

This happens because the snow is placed first in a chunk. When the rest of the chunk is decorated, a tree can generate elsewhere (such as a neighbouring chunk) that projects into the previously-decorated section. Result: snow ends up placed under the portion of the tree that projects over the older section and not on top of it. The borders of the misplaced snow are always aligned with the edge of the chunk. (Amended from earlier version: the original report stated that the behaviour occurred for 8×8 quarter-chunks; this is no longer happening.)

A similar effect can be seen in ice spikes biomes. Some patches of compressed ice are generated flush with the ground. Sometimes these generate partially covered in snow even though compressed ice is usually snow-free.

A suggested fix: add a sanity check for snow cover in newly-generated chunks, and adjust it as needed. (Move it to the tops of newly-generated trees, or remove it from newly-generated ice spikes.)

Steps to Reproduce

• Locate and enter a biome that generates both snow and trees, for example, a "snowy_taiga".

• Fly over the trees within this biome and take note as to whether or not if snow is sometimes able to generate below trees.

Observed Behavior

Snow sometimes generates below trees instead of on top of them.

Expected Behavior

Snow would always generate on top of trees instead of below them.