On Thu, Apr 05, 2018 at 02:51:22PM +0200, Martin Liška wrote:
> On 04/04/2018 09:31 PM, Marek Polacek wrote:
> > On Tue, Apr 03, 2018 at 02:29:37PM +0200, Martin Liška wrote:
> >> Hi.
> >>
> >> This helps the warning with --save-temps. Doing that one needs to preserve
> >> comments
> >> in preprocessed source file.
> >
> > Do we really want to only use -C when -Wimplicit-fallthrough is in effect?
> > I
> > mean, shouldn't we always use -C when -save-temps?
>
> Why not, Jakub what do you think? Note that it was originally Jakub's idea to
> do that.
I'd prefer to do that only when we actually care about the comments, it is a
behavior change in any case, and might be undesirable to some people.
Note that we do not care about the comments if -Wimplicit-fallthrough=0
or -Wimplicit-fallthrough=5, but do care for:
-Wimplicit-fallthrough
-Wimplicit-fallthrough=1
-Wimplicit-fallthrough=2
-Wimplicit-fallthrough=3
-Wimplicit-fallthrough=4
-Wextra
-W
(unless -Wno-implicit-fallthrough). So, it would be desirable to:
1) swap the order, put save-temps to the outer level
2) use
{Wimplicit-fallthrough*:{!Wimplicit-fallthrough=0:{!Wimplicit-fallthrough=5:...}}}
3) verify (including adding testcases) that it doesn't emit comments for the
=0, =5 or -W -Wno-implicit-fallthrough cases, but does for -W etc.
Jakub
