Re: Changes in C++ FE regarding pedwarns to be errors are harmful

[Mark Mitchell <mark at codesourcery dot com>]

Joe Buck wrote:
> Mark Mitchell wrote:
>>> I don't see any a priori problem with changing to match the C front end.
>>> We could of course change some of the pedwarns into errors if we really
>>> think they ought to be errors.  Or, some of them could be ordinary
>>> warnings when not -pedantic, and pedwarns when -pedantic.

>> Sounds like we want a separate category of diagnostic with the current 
>> C++ pedwarn semantics so that we can change pedwarns themselves back to 
>> a warning by default.
> 
> Agreed.  Some have argued that the change makes sense because of
> consistency arguments.  I'm not impressed with that; the compiler
> is designed to be used, so the question is what most serves the users.

Exactly so.  I think that we have two kinds of pedwarns: those that are
pedantic in the sense we use for C (like, that there cannot be a naked
semicolon at the top-level of a file, or that "long long" is not in
C++98) and those that refer to semantically reasonable constructs that
we previously accepted, often because they were allowed by cfront or the
ARM.  With flag_permissive, we probably want the latter category to be
warnings at most; without flag_permissive, we want them to be errors.

This is a conceptually simple project, but it will take some work to
implement it, because someone will have to look at every pedwarn and
decide which category they are in.  Any volunteers?

-- 
Mark Mitchell
CodeSourcery
mark@codesourcery.com
(650) 331-3385 x713