Physics2D Circlecast Hit result is not on collider

Physics isn't about giving you exact geometry intersections, you'll need to use your own library for that; it's about where it would consider a contact. In most cases offsets for polygons uses the DefaultContactOffset. Note that the above is 2.5mm and should be considered trivial.

 

It's not that CircleCasts do use it but more that Raycasts don't. All shape casts and collider overlaps use the same physics code (Box2D) that's used to calculate contacts during the physics simulation step. Raycasts and OverlapPoint are not used by the physics system and are pure utility intersection queries against colliders and as such don't incorporate that into them.

As an aside, the physics system only uses conatct offset on intersections with polygons which is why in Box2D it's known as b2_polygonRadius; circle/circle don't use it.

All I can say is that raycast not taking default contact offset into account is the least of your issues if you're using raycast to detect collisions because after all, it's a swept point and unelss your collider(s) are points it'll never be accurate which is why there's swept collider/rigidbody support i.e. Cast. There's also Rigidbody2D.Distance and Collider2D.Distance which help determining overlap or separation and ways to solve it to move into contact without overlap or out of overlap (iteratively) etc.

You could also take a look at my GitHub repo, specifically this scene which shows you Kinematic movement combining swept colliders and Distance calls to move/slide around. That can be seen here:

 

I'd not seen that before so I just spun-up the project and yes I could reproduce it. It was a simple fix though which I pushed to master here as well as a minor change similar to what you suggested here. Just pull those changes. The issue was that it was overshooting the target continually so the move needs to be limited to the actual target position otherwise overshoot means it's oscillating through the target position when the target is less than the move-speed/time. Thanks for the report.

Well it's breaking down the words Ray & Cast. Cast (or sweep) means project or move something through a space. When you do a Circle Cast it's a cast (sweep) of a circle through space. A ray therefore is a point cast through space.

You can get a ray to hit an obstacle where a circle wouldn't. Using a ray to detect where a character would hit might be easy but it's not accurately representing where a circle would hit as the circle has an area.

 

Well it works and can be adequate but it's not an accurate representation of whether your non-ray-shaped character will hit at that point so it's a compromise if that makes sense.