Is Erlang's recursive functions not just a goto?

A tail recursive call is more of a "return and immediately call this other function" than a goto because of the housekeeping that's performed.

Addressing your newest points: recording the return point is just one bit of housekeeping that's performed when a function is called. The return point is stored in the stack frame, the rest of which must be allocated and initialized (in a normal call), including the local variables and parameters. With tail recursion, a new frame doesn't need to be allocated and the return point doesn't need to be stored (the previous value works fine), but the rest of the housekeeping needs to be performed.

There's also housekeeping that needs to be performed when a function returns, which includes discarding locals and parameters (as part of the stack frame) and returning to the call point. During tail recursive call, the locals for the current function are discarded before invoking the new function, but no return happens.

Rather like how threads allow for lighter-weight context switching than processes, tail calls allow for lighter-weight function invocation, since some of the housekeeping can be skipped.

The "goto &NAME" statement in Perl is closer to what you're thinking of, but not quite, as it discards locals. Parameters are kept around for the newly invoked function.

One more, simple difference: a tail call can only jump to a function entry point, while a goto can jump most anywhere (some languages restrict the target of a goto, such as C, where goto can't jump outside a function).

You are correct, the Erlang compiler will detect that it is a tail recursive call, and instead of moving on on the stack, it reuses the current function's stack space.

Furthermore it is also able to detect circular tail-recursion, e.g.

test() -> ..., test2().
test2() -> ..., test3().
test3() -> ..., test().

will also be optimized.

The "unfortunate" side-effect of this is that when you are tracing function calls, you will not be able to see each invocation of a tail recursive function, but the entry and exit point.

You've got two questions here.

First, no, you're not in any danger of overrunning the stack in this case because these calls to test() are both tail-recursive.

Second, no, function calls are not goto, they're function calls. :) The thing that makes goto problematic is that it bypasses any structure in your code. You can jump out of statements, jump into statements, bypass assignments...all kinds of screwiness. Function calls don't have this problem because they have an obvious flow of control.