Re: RFC: -Wall by default

[Gabriel Dos Reis <gdr@integrable-solutions.net>]

On Wed, Apr 4, 2012 at 8:19 PM, Robert Dewar <dewar@adacore.com> wrote:
> On 4/4/2012 7:03 PM, Gabriel Dos Reis wrote:
>
>> Again, this proposal does not come out of a whim.
>
>
> But it does seem to come out of a few anecdotal requests
> for a change,

It does appear very disturbing that you would dismiss repeated
requests on the basis that they are anecdotal without offering
evidence.  What is more, we seem to have implemented a feature
that makes it even more intimidating for potential users to fill
out such requests.

> and you always have to be careful in considering
> such input, because of course people who agree with the status
> quo do not write in complaining.

I do see evidence to the contrary to that claim, starting with this
very thread AND the bugzilla database that we seem to have
designed to intimidate future requesters.

> I see no evidence that a
> majority of users are in favor of this change.

This strikes me as a way to a self-fullfilling prophecy.

> By the way, to me a much more significant issue is the default
> optimization level. Gcc code quality is plain horrible at -O0,
> often MUCH worse that competitive compilers with default
> optimization (most compilers do much more than -O0 by default).

One cannot seriously argue for "do what it is told" and at the
same time complain about default level of optimization :-)  Furthermore,
the problem you see with the default level of optimization is not in
conflict with default level of diagnostics.  I am approaching the issue
from the point of view of diagnostics maintainer; if you want to raise
the default level of optimization you should feel free to make a proposal.

> We have run into people running benchmarks where they were
> specifically prohibited from using other than the default
> options, and gcc fared badly in such comparisons.

That is no argument against diagnostic level by default. In fact, it
appears to support the claim that many users run the compiler
without options -- and the argument of -Wall being short to remember
is evenless potent since -O is even shorter to remember.


>
> So we have wondered from time to time whether -O1 should
> be the default, but the debugger is not well behaved at
> -O1, and it's too much of a change I am afraid.

Again, that isn't an argument against more useful diagnostic level by default.

-- Gaby