On world load Hostiles can spawn on top of melons.

[Panda]

Maybe this is just something in my world but upon every load melons have low light level tops until approached (5-7 blocks away from it). Ive dubbed it the the watermelon monster patch. also Im using Ender goggles and as you can see one melon has a torch right next to it also.

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[Daisjun]

I wasn't able to replicate this using placed or grown melons. Also tried different moon lighting levels and still couldn't replicate it.

[Soaplegs]

I have consistently been able to recreate the bug, and my melons are planted on the same height as yours relative to the lake(I believe y=64 in my case, looks like it could be the same for you) I suspect it could have something to do with the height.

[Daisjun]

That seems to have done the trick. Can confirm this happens at sea level.

From a distance they will be darker than they should be, then as you get closer they show the spawn squiggles, closer again and they will brighten to the correct lighting level and the squiggles will disappear.

EDIT: The same thing appears to happen in vMC 1.5.2, looks like a vanilla bug. Screenshots taken in vMC, look at the melons on the left:

Before

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After

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[FlowerChild]

I think I recently saw something related to this recently where a pumpkin patch didn't seem to have the right lighting. Will investigate further.

[ion]

happens sometimes in the world with some blocks that don't receive the proper lighting. in mine i was able to fix that by just moving one torch from one block to another. i can't remember if the torch was on a chunk border, but i can confirm that it was under clear sky. height was around 80-90 y
hope that it helps.

[FlowerChild]

Yeah, it's not just melons:

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It appears to occur with any block at sea level. I setup the above pictured test case in creative, and reproduced it consistently by moving out of load range of the melon patch and back in. Just added the cobble patch in a similar pattern to the melons, and it's doing exactly the same thing.

I'm wondering if this might also be related to how swamp trees seem to get a lot more lighting glitches under them than others, given they tend to all be around sea level.

Will start digging into it. Just wanted to verify that I've managed to consistently reproduce this.

[FlowerChild]

I know it's implied in the original post, but can anyone verify that mobs can actually spawn in invalid locations as a result of this?

I'm beginning to suspect this might strictly be a visual thing on the client end, while the server code (which handles mob spawning), might be working just fine.

It just occurred to me that with this apparently happening on every block, I can't really see mobs spawning in people's sea level bases due to this would have gone this under-reported for so long, and that while people have reported seeing the ender spec indicator that mobs can spawn in these places (as have I), nobody has actually mentioned seeing actual mobs in them.

[FlowerChild]

Nah, at this point I'm quite confident this is just visual.

I setup some debug code to let me know when those blocks were capable of spawning mobs on both the client and server (this is in single player as well). The code is routinely tripped on the client, but not the server, which is where the actual mob spawning occurs.

So, there shouldn't be any gameplay related problems here, even if it's visually disconcerting to see these dark spots.

I won't try to fix this for now then, since it's vanilla, and since I intend to attempt a revamp of lighting in the future to fix the numerous problems that can occur with it.

Will leave this bug open for a day or so in case anyone has any additional info to add.

[FlowerChild]

K, since there are no objections: Will not fix (for now).