Microcontroller programmers tend to fall into the trap of trying to bind a variable to a CPU register, and declare it "volatile" so they could e.g. use it to communicate between the main context and an ISR.
Previous GCC versions issued a warning: volatile register variables don't work as you might wish This warning has been removed without making volatile register variables work the way an innocent programmer would assume. Please re-enable that warning at least for -Wall and/or -Wextra. -- Summary: Please get us the "volatile register" warning back Product: gcc Version: 4.1.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: j at uriah dot heep dot sax dot de http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34351