Noteworthy changes in release 2.6.6 (2026-11-11) [stable]

build

• tools/bootstrap-flex now builds flex 2.6.5 and checks its signature
  against the flex release key, as well as its hash. It needs gpg.

scanner

• A generated scanner no longer fails to compile in a program that
  defines a macro named fallthrough, as the Linux kernel's headers do.
  Flex 2.6.5 wrote the fall-through marker with that plain name, so
  the macro was expanded inside the scanner. The scanner now uses the
  reserved spelling fallthrough for the attribute. (#842)

  Thanks to Luca Bacci; reported by Philip Müller.