Quoting Bjørn Mork <bjorn@xxxxxxx>:
"Gustavo A. R. Silva" <garsilva@xxxxxxxxxxxxxx> writes:
In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Notice that in this particular case I replaced "...drop on through"
comments with a proper "fall through" comment on its own line, which
is what GCC is expecting to find.
Sounds to me like GCC is the wrong tool for this. But I would of course
not mind if it was *just* the text. However, as your patch cleary
shows, the simplified logic leads to real problems:
@@ -1819,8 +1819,8 @@ static void process_rcvd_data(struct
edgeport_serial *edge_serial,
edge_serial->rxState = EXPECT_DATA;
break;
}
- /* Else, drop through */
}
+ /* fall through */
case EXPECT_DATA: /* Expect data */
if (bufferLength < edge_serial->rxBytesRemaining) {
rxLen = bufferLength;
The original comment clearly marked a *conditional* fall through at the
correct place. Your patch makes it appear as if there is an
unconditional fall through here. There is not. The fallthrough only
applies to one of a number of nested if blocks. There are no less than
3 break statements in the same case block.
I see.
You are right.
Not a big deal maybe, just as the lack of any "fall through" comment
isn't a big deal in the first place. But this change is clearly making
this code harder to read, and the change is therefore harmful IMHO.
If you can't make -Wimplicit-fallthrough work without removing such
precise fallthrough markings, then my proposal is to drop it and use
some other tool.
I will talk with the hardening guys to see what we can do about this.
I appreciate for your comments.
Thanks
--
Gustavo A. R. Silva
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