Old cave and ravine generation gets cut off unnaturally on chunk borders near water

Apparently affects ravines as well.

18w08a example (in case the old ones no longer work): /tp @p -3124 80 3156, 6681878277208838608.

1.13 example:

Seed: 5203146265350693241

/execute in overworld run tp @s 88.80 67.08 -9.63 121.93 34.73

Confirmed for 1.13.1.

Discovered an instance of this in 1.14.1 pre-release 2

Seed: -2998127435321252675

Coordinates: X: -58 | Z: 546

Another example: Seed: -3070852984194394850, coords -200/60/160

Still in 1.15

I can still produce the bug in the snapshot 20w11a and all of 1.15+ releases.
It's annoying.
This bug is not on Bedrock.

affects 20w12a

Caves are still weird in 20w13a, indicating this version is affected.

20w14a - affected

20w15a has this problem

See MC-411. Duplicate or at least related to. EDIT: note: its state of "invalid" is basically a forgotten state, it should have been reopened for proper evaluation.

Still affects 1.16pre1

Seed: 8470219322699000237
Approximate coordinates in screenshot: -47, 75, -18

Confirmed in 20w29a

Can confirm in 20w51a. Here's an example with a ravine.

Seed: -6178286686098098179
Coordinates: /execute in minecraft:overworld run tp @p -72 68 -1717 90 50

Here's one with an underwater ravine:

Seed: -5436467103508185805
Coordinates: /execute in minecraft:overworld run tp @s 432153.00 44.35 466.82 -322.57 48.99

Can confirm in 21w05a.

Definitely worse in 21w15a than 21w05b.

Unfortunately this bug wasn't fixed in 21w18a.

Can confirm in 21w18a with Avoma's first seed.

Caves being cut of seems to have happened because of 2 different causes:

1. Because the biome of the chunk where it was supposed to generate in didn't have that carver enabled (rivers don't have any carver enabled). This is the main cause that this issue is reporting and has indeed been fixed in 21w18a.

2. Because the maximum distance from the starting chunk has been reached. This has nothing to do with the existence of water. The first example by Avoma (-6178286686098098179 at -72 68 -1717) has this issue (there is no water biome anywhere that could cause this cut-off). This hasn't been fixed but isn't what this issue is reporting.

I don't think there is a distinction between "water biomes" and the other ones. You can turn any biome into an ocean with a datapack by simply changing the depth parameter. When a biome has terrain below y=63, it will always get flooded, which is why you can still find lakes in deserts (MC-72831) or other low biomes.

I think the caves check for water blocks in some places, but they seem to "miss" if the water patches are too small, causing MC-132285.

Can confirm still in 21w18a, despite labeled as fixed.

Confirmed in 1.17.

Can this still be seen in 21w38a?

I couldn't reproduce this in 21w40a, although obviously I wasn't able to check the areas from prior reports due to the biomes being enlarged in this snapshot.