[M3commit] CVS Update: cm3

[Jay K]

unsigned F1()
{
 unsigned a;
return a;
}

should generate a warning.

unsigned F1()

{

 unsigned a = 0;

return a;

}


is much preferred.

Just because the front end is ok with the first, doesn't make it correct.

 - Jay

----------------------------------------
> Subject: Re: [M3commit] CVS Update: cm3
> From: hosking at cs.purdue.edu
> Date: Mon, 5 Jul 2010 17:34:51 -0400
> CC: m3commit at elegosoft.com
> To: jay.krell at cornell.edu
>
> Huh?
>
> On 5 Jul 2010, at 17:15, Jay K wrote:
>
> >
> > At least some of these were Word.T. "valid" is still "random" and the code is unpredictable, at least by a quick read, even if type safe.
> > Type safe is just a minimum bar, one that should always be exceeded, even if the compiler is completely unable to validate it.
> >
> > That is, the compiler guarantees are from sufficient relative to correctness.
> >
> > - Jay
> >
> > ----------------------------------------
> >> From: hosking at cs.purdue.edu
> >> Date: Mon, 5 Jul 2010 16:50:00 -0400
> >> To: jay.krell at cornell.edu
> >> CC: m3commit at elegosoft.com
> >> Subject: Re: [M3commit] CVS Update: cm3
> >>
> >> But we've been this route before. Modula-3 ensures every variable is initialised with a valid value. I don't see how your adding an initialiser makes it more obviously correct.
> >>
> >> On 5 Jul 2010, at 16:45, Jay K wrote:
> >>
> >>>
> >>> I will maybe see about doing better here.
> >>> Initializing locals doesn't seem like such a bad change though.
> >>> I like the code to be "obviously correct" by a quick read by a human.
> >>>
> >>> - Jay
> >>>
> >>> ----------------------------------------
> >>>> From: hosking at cs.purdue.edu
> >>>> Date: Mon, 5 Jul 2010 14:31:01 -0400
> >>>> To: jkrell at elego.de
> >>>> CC: m3commit at elegosoft.com
> >>>> Subject: Re: [M3commit] CVS Update: cm3
> >>>>
> >>>> Jay, I am perplexed that we are adding things to Modula-3 source because of compiler backend brokenness just to avoid back-end warnings. Better to fix the backend so that RAISE is noreturn. This should not be difficult to do.
> >>>>
> >>>> On 5 Jul 2010, at 15:22, Jay Krell wrote:
> >>>>
> >>>>> CVSROOT: /usr/cvs
> >>>>> Changes by: jkrell at birch. 10/07/05 15:22:28
> >>>>>
> >>>>> Modified files:
> >>>>> cm3/m3-tools/cvsup/suplib/src/text_cm3/: SupMiscText.m3
> >>>>>
> >>>>> Log message:
> >>>>> ../src/text_cm3/SupMiscText.m3: In function 'SupMisc__DecodeWS':
> >>>>> ../src/text_cm3/SupMiscText.m3:211: warning: 'M3_Bkn9rd_ch' may be used uninitialized in this function
> >>>>> ../src/text_cm3/SupMiscText.m3:211: note: 'M3_Bkn9rd_ch' was declared here
> >>>>>
> >>>>> because raising an exception isn't currently "noreturn"
> >>>>> so initialize it to 0
> >>>>
> >>>
> >>
> >
>