Haste vs. Rapid shot or Flurry of blows

[orlondok]

There is a conflict of opinions/understanding of some rules in our D&D campaign, and I wanted to seek opinions / clarification here. Haste spell says that the extra attack does not stack with things like a weapon of speed. Our present DM has chosen to decipher this as not adding an extra attack when a feat or class ability such as rapid shot or flurry of blows already grants one ... Should feats or class abilities which are not derived from a magical source, that allow extra attacks, stack with the Haste spell?

[Segev]

Feats are not granting extra attacks via magical speed. They stack. The weapon of speed is essentially a perma-haste effect, which is why it doesn't stack.

[StreamOfTheSky]

Rapid Shot and Flurry both stack with Haste, and would stack with each other (shuriken throwing?). Haste just doesn't stack w/ haste-like effects, which are always spelled out. Speed weapon property, some 4th level cleric spell I forget the name of, etc...

[MaxiDuRaritry]

Haste matches with those other, non-speed effects, as mentioned above. Haste doesn't stack with any enhancement bonus to speed, however, including boots of speed, horseshoes of the zephyr, or the monk's speed boost.

[Khedrac]

I would agree that by RAW the extra attack from haste does not stack with those from flurry of blows or rapid shot, however that is not how I DM.
The "not stacking" text does not mention magic so what is meant by "similar sources" is entirely up to the DM.