Re: [PING^3] Wconversion: fixes for C++ front-end

["Manuel López-Ibáñez" <lopezibanez at gmail dot com>]

On 08 Feb 2007 07:30:44 -0600, Gabriel Dos Reis <gdr@cs.tamu.edu> wrote:
> "Manuel López-Ibáñez" <lopezibanez@gmail.com> writes:
>
> [...]
>
> | > Make a list of all th without extensively modifying the C and C++ front-ends.e places where the C++ front-end does not call
> | > convert_and_check (that is already contained in your patch).
> |
> | I don't understand this. Do you mean the places where the C++
> | front-end calls a conversion function instead of convert_and_check ?
>
> Yes.  Essentially, you can trace brack from ocp_convert, with a grep...
>
> For ocp_convert() I have: force_rvalue(), cp_convert(), convert(),
> convert_force(), initialize_handler_parm(), expand_default_init(),
> convert_nontype_argument(), build_static_cast_1,
> convert_for_initialization().

I have looked to those functions and I still don't understand what you
want me to do. I tried modifying ocp_convert to add the warnings there
and a new argument 'issue_conversion_warnings' as in
'convert_like_real', but the required modifications are too large and
intrusive. I really don't know how to implement your suggestion.

As an alternative, I have prepared the following patch. It addresses
the concerns about the original patch in two ways. First, it adds a
new function cp_convert_and_check, so 1) no need to call convert when
we actually want cp_convert, and 2) no result is thrown away.

Secondly, in 'convert_like_real', it uses the already existing call to
convert_and_check to detect conversions from floating-point to
integer, no additional call to convert_and_check is needed any more.
In order for this to work for references, we need to pass the original
value of issue_conversion_warnings to subsequent calls to
convert_like_real.

It bootstraps and passes all regression tests. Do you see any
potential problem with this version?

Cheers,

Manuel.

:ADDPATCH C++:

2007-02-10  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

 * doc/invoke.texi (-Wconversion): Document warnings specific to C++.
 * c-common.c (convert_and_check): Move warning logic to...
 (warnings_for_convert_and_check): ...here. Define.
 * c-common.h (warnings_for_convert_and_check): Declare.

cp/
  * cvt.c (cp_convert_and_check) : Define.
  * cp-tree.h (cp_convert_and_check): Declare.
  * call.c (convert_like_real): Use convert_and_check instead of
custom warning.
  * typeck.c (build_binary_op): Use cp_convert_and_check to warn for
overflow and changes of value during conversion.

testsuite/
  * g++.dg/warn/Wconversion-integer.C: New
  * g++.dg/warn/Wconversion-real.C: New.
  * g++.dg/warn/Wconversion-real-integer.C: New.
  * g++.dg/warn/conv2.C: Modified.

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