I was just browsing the SRD to see if there was anything definitive on the subject of "No damage equals a miss".
Here's what I found:
SRD said:
ATTACK ROLL
An attack roll represents your attempt to strike your opponent on your turn in a round. When you make an attack roll, you roll a d20 and add your attack bonus. (Other modifiers may also apply to this roll.) If your result equals or beats the target’s Armor Class, you hit and deal damage.
That's it. You roll over the AC and you hit and deal damage. It doesn't say, "Roll over the AC and do damage, and you hit."
Equally interesting (or perhaps more) is the section that immediately follows:
SRD said:
DAMAGE
When your attack succeeds, you deal damage. The type of weapon used determines the amount of damage you deal. Effects that modify weapon damage apply to unarmed strikes and the natural physical attack forms of creatures.
Damage reduces a target’s current hit points.
Minimum Damage: If penalties reduce the damage result to less than 1, a hit still deals 1 point of damage.
Strength Bonus: When you hit with a melee or thrown weapon, including a sling, add your Strength modifier to the damage result. A Strength penalty, but not a bonus, applies on attacks made with a bow that is not a composite bow.
Off-Hand Weapon: When you deal damage with a weapon in your off hand, you add only 1/2 your Strength bonus.
Wielding a Weapon Two-Handed: When you deal damage with a weapon that you are wielding two-handed, you add 1-1/2 times your Strength bonus. However, you don’t get this higher Strength bonus when using a light weapon with two hands.
In the spirit of intellectual honest, I will point out that the highlighted section refers to penalties to damage, and that DR isn't described as a "penalty". I suspect that it's referring to things like silver weapons (which do 1 point less than normal versions), or damage from characters with Strength scores below 10.
I only bring that up because it highlights that DR isn't a damage penalty. You hit that Stone Golem with a 2x4 (makeshift weapon), you still deal damage. He gets to reduce that damage by his DR, which probably drops it to zero, but you did in fact roll for damage, so any argument that no damage equals no hit is bogus.
Consider this scenario: You use
Disintegrate on the floor at the feet of a Golem, turning the formerly solid earth into a 10 foot pit. He falls, as if into a 10 foot pit, taking damage appropriate for falling into a 10 foot pit (i.e. a D6 of damage). Since the floor wasn't Adamantine, his DR applies and he takes no damage.
Does that mean he didn't actually hit the bottom of that pit? Has he mastered
Flight by throwing himself at the ground and missing?
(If you say Yes, I have a Barbarian who's going to just love this ruling
)