Why not rely on implicit sinking of switch statements in C++?
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ES.78: don't rely on implicit sinking of switch statements
Reason (reason)
Always end a non-empty case with a break. Accidentally leaving out a break is a fairly common bug. A deliberate fallthrough can be a maintenance hazard and should be rare and explicit.
Typically, break is used to abort a non-empty case processing. Accidentally missing a break is usually a mistake. Intentional sinking treatment may bring maintenance risks and should be used less and explicitly.
Example (sample)
Switch (eventType) {
Case Information:
Update_status_bar ()
Break
Case Warning:
Write_event_log ()
/ / Bad-implicit fallthrough
Case Error:
Display_error_window ()
Break
}
Multiple case labels of a single statement is OK:
There is no problem with multiple tags in a statement.
Switch (x) {
Case'asides:
Case'baked:
Case'fags:
Do_something (x)
Break
}
Return statements in a case label are also OK:
There is no problem using the return statement in the case tag:
Switch (x) {case'asides: return 1; case'baked: return 2; case'cages: return 3;}
Exceptions (exception)
In rare cases if fallthrough is deemed appropriate, be explicit and use the [[fallthrough]] annotation:
In rare cases, if you are sure that the sinking treatment is appropriate, you can clearly indicate it using [[fallthrougn]] notation.
Switch (eventType) {
Case Information:
Update_status_bar ()
Break
Case Warning:
Write_event_log ()
[[fallthrough]]
Case Error:
Display_error_window ()
Break
} Note (Note) Enforcement (implementation recommendation)
Flag all implicit fallthroughs from non-empty cases.
Marks all implicit sinking processing from a non-empty case.
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