A malformed `scf.for` whose body block contains no arguments caused
`getRegionIterArgs()` to crash via an out-of-bounds `drop_front(1)`
call. This happened because `verifyLoopLikeOpInterface` (a
`verifyRegionTrait`) invokes `getRegionIterArgs()` during
`verifyRegionInvariants`, which runs before `verifyRegions()` has a
chance to report a proper diagnostic.
Fix by adding an explicit check in `ForOp::verify()` (which runs in
`verifyInvariants`, before any region trait verifiers execute) that
ensures the body block has at least as many arguments as there are
induction variables. This prevents the crash and produces a clear error
message.
Fixes#159737
2cb2fe7f2a