Compiler allows unlimited use of `unsafe` keyword

[natecook1000]

Description

While I appreciate the opportunity for histrionics, we should probably cap the number of times you're allowed to write the unsafe keyword at 1. The code below compiles for me using the June 12 nightly toolchain.

Reproduction

func superDuperUnsafe(_ bytes: UnsafeRawBufferPointer) {
  let byte = unsafe unsafe unsafe unsafe unsafe unsafe unsafe bytes.first ?? 0
  print(byte)
}

Expected behavior

A compiler error on the second (and following) use of unsafe

Environment

Apple Swift version 6.2-dev (LLVM d266fd9f80a7945, Swift 665515c)
Target: arm64-apple-macosx26.0
Build config: +assertions

Additional information

rdar://153672668

[ZevEisenberg]

One is reminded of 'long long long' is too long.