The must package isn't suitable for use in hot paths. The main problem is that it takes printf-style format args as []interface{}:

This has a couple of problems: the interface boxing incurs an allocation for certain types, and arguments can escape to the heap. One might hope that the compiler deferred the boxing until after the a == b condition when inlining, but no such luck.

Most likely, the better option is to significantly simplify the API. Something basically similar to:

if a != b {
  return must.Fail(ctx, "a=%v != b=%v", a, b)
}

This only incurs the cost of boxing on the unhappy path, and the heap escape can similarly be deferred by copying the format args value in the branch.

However, let's consider some other options here, and see if we can come up with something suitable.

Jira issue: CRDB-30342