[fpc-devel] Submitted bug report on option order -Sa -Sg-

[Tom Verhoeff]

On Sun, Apr 15, 2007 at 09:51:55PM +0200, Tomas Hajny wrote:
> On 15 Apr 07, at 21:14, Tom Verhoeff wrote:
> > On Sat, Apr 14, 2007 at 06:56:12PM +0200, Jonas Maebe wrote:
> > > On 13 Apr 2007, at 17:38, Tom Verhoeff wrote:
> > > 
> > > >The order -Sa -Sg- fails to generate assertion checking code, whereas
> > > >this is generated for the order -Sg- -Sa.
> > > >
> > > >A separate test confirms this (mis)behavior (see bug report: Steps To
> > > >Reproduce).
> > > >
> > > >Or am I missing the obvious, and is this really a feature and not a  
> > > >bug?
> > > 
> > > -S- disables all the -S options, regardless of where the second -  
> > > appears (like -O- disables all -O options). This can indeed be  
> > > confusing, since e.g. -Cor- turns on overflow checking, but disables  
> > > range checking. This is indeed not consistent. Both cases work as  
> > > designed, but the design is obviously not optimal.
> > 
> > Thanks for the explanation.  I think I understand what you are saying.
> > 
> > In the (on-line) User's Guide, I can't find anything about the use of
> > a trailing - for options.  Where is this documented?
> > 
> > How would one disable just the goto statement, without affecting other
> > -S options?
> > 
> > By the way, the User's Guide states that goto statements are disabled
> > by default.  However, the reason we added the -Sg- (attempting to disable
> > just goto statements) was because after upgrading, suddenly programs
> > with goto were accepted (and we don't want that in our educational use
> > of Pascal).  Hence, we added the option.
> 
> The default mode is -Mfpc nowadays. Modes FPC and 
> OBJFPC don't have goto enabled by default (i.e. -
> Sg is required to enable it), so the docs are 
> correct (modes TP and Delphi both have -Sg 
> enabled for compatibility reasons).
> 
> 
> > Could it be that the default configuration file also got changed by the
> > update and now enables goto statements?  (This would be confusing.)
> 
> This seems to be the case indeed (see 
> /fpcsrc/compiler/utils/samplecfg, 
> /fpcsrc/compiler/utils/fpc.cft, 
> /fpcsrc/compiler/utils/fpinc.cfg and 
> /fpcsrc/installer/install.dat). General question -
>  do we want to change this (taking into account 
> that having some default in the compiler and then 
> changing it into something different in the 
> default configuration file looks strange)?
> 
> If nothing else, you can obviously change this in 
> your own configuration files, of course.

So, it is now not possible to switch off goto statements in Delphi
mode by just giving some command-line options.  It requires an adapted
configuration file, or knowing exactly what options are implicitly
set for -Mdelphi, and copying those, except -Sg, on the command-line.
Or do I overlook a simpler possbility?

My question about where -O-, -S-, and -Cx- are documented is
still open...  (I like to read manuals, but couldn't find anything.)

I have added a clarifying note to my original bug report (#0008686).
The original bug report is thereby resolved, but there are still some
related open ends:

  *  Documentation explaining -Sxxx-
  *  Defaults in standard config file(s) versus defaults for compiler
     (w/o config file)
  *  Simpler way to switch off single -S options

Thanks,

	Tom
-- 
E-MAIL: T.Verhoeff @ TUE.NL     | Dept. of Math. & Comp. Science
PHONE:  +31 40 247 41 25        | Technische Universiteit Eindhoven
FAX:    +31 40 247 54 04        | PO Box 513, NL-5600 MB Eindhoven
http://www.win.tue.nl/~wstomv/  | The Netherlands