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Re: GDB -Wmissing-prototypes and flex troubles
- From: Mark Kettenis <mark dot kettenis at xs4all dot nl>
- To: brobecker at adacore dot com
- Cc: pierre dot muller at ics-cnrs dot unistra dot fr, gdb at sourceware dot org
- Date: Wed, 13 Jun 2012 07:57:34 +0200 (CEST)
- Subject: Re: GDB -Wmissing-prototypes and flex troubles
- References: <004801cd48f1$e6599080$b30cb180$@muller@ics-cnrs.unistra.fr> <20120613043748.GB2709@adacore.com>
> Date: Tue, 12 Jun 2012 21:37:48 -0700
> From: Joel Brobecker <brobecker@adacore.com>
>
> > Should we:
> > 1) Specify a minimal version for flex?
> > 2) disable missing-prototypes option
> > for ada-exp.c compilation?
> > 3) Do 2) if version if below
> > minimum version adding those prototypes?
>
> The lazy way would be to require a minimal version for flex.
> I would be OK with that, although it is true that it is a bit of
> a shame that the user does not get an error at configure time.
> It should be relatively easy to do, except that this would force
> me to upgrade many installs of flex on some of AdaCore's machines.
> I don't mind doing the update too much, and I should, except
> I usually find out at the wrong moment, and I then just get past
> the error by copy/pasting the compile command, removing the -Werror
> flag, and then resume the build. And also, an error would be
> preventing people from building a release with an older version
> of flex, even though the warnings would be harmless and non-fatal.
>
> I don't think we want to unilaterally disable -Werror for ada-lex.c.
> We'd open the door to allowing warnings back in again, when we did
> all the work to clean them up.
>
> A variation of 3. Something like the following close to the start
> of ada-lex.l:
>
> #if <FLEX_VERSION> < <2.5.35>
> /* Older versions of flex do not provide prototypes for these functions.
> Provide them ourselves, to avoid -Wmissing-prototypes warnings. */
> int yylex_destroy (void );
> int yyget_debug (void );
> void yyset_debug (int debug_flag );
> YY_EXTRA_TYPE yyget_extra (void );
> [...]
> #endif
>
> I am not completly sure that this is going to work, maybe if some
> types are missing, for instance. Or maybe the prototypes depend on
> the version of flex.
>
> With all this being said, your option (3) is attractive. Except
> that in terms of implementation, it forces us to have a special
> rules for ada-lex.o.
>
> All in all, I tend to vote for the status quo...
Same here. The version of flex in the OpenBSD base system reports
itself as 2.5.4, yet I don't see the problem that Pierre reports. So
it seems that the problem was introduced in a later version and then
fixed again. Given that there is a workaround, and releases don't
suffer from the problem because we disable -Werror there, I'd say we
leave things as they are.