On 26 September 2011 09:40, Olaf van der Spek <ml@vdspek.org> wrote:
On Mon, Sep 26, 2011 at 3:47 PM, Christian Holmquist <c.holmquist@gmail.com> wrote:
On 26 September 2011 06:02, Olaf van der Spek <ml@vdspek.org> wrote:
On Mon, Sep 26, 2011 at 8:30 AM, Christian Holmquist <c.holmquist@gmail.com> wrote:
Sometimes types unfortunately have implicit conversion, and if the compiler finds them (I guess that what's common_type deduces?),I might end up with a bogus expression that unfortunately compiles.
Could you give a concrete example (with 3 type clamp)?
enum A{a}; enum B(b); main() { clamp(0, a, b); }
Right. g++ 4.6: warning: enumeral mismatch in conditional expression: ‘A’ vs ‘B’
Ok, it's good that gcc warns about this. MSVC doesn't.
Is this really the fault of clamp() though?
No, but clamp can avoid exposing this inherited problem, just as std::min/std::max does. The same 'mistake' can easily be made in normal code.
Yes, and it is causing trouble. We can't go back and change the rules for implicit conversions between native types, but when there is a possibility to get rid of the legacy I think one should opt to do so.
Olaf
Christian