https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63458
Eric Gallager <egallager at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2017-08-25
CC| |egallager at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #5 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Marc Glisse from comment #1)
> You forgot to mark your operator bool as explicit.
That's bug 60135, I think.
(In reply to mqi30097 from comment #0)
> Why no warning whatsoever??
>
> //================= go.cpp ======================================
> #include <iostream>
>
> class Mystream
> {
> public:
> Mystream(std::istream& is1) : is{is1} {}
> Mystream& operator>>(std::string&);
> operator bool();
> private:
> std::istream& is;
> };
>
> Mystream& Mystream::operator>>(std::string& s)
> {
> is >> s;
> return *this;
> }
>
> Mystream::operator bool()
> {
> return is.good();
> }
>
> int main()
> {
> Mystream ms(std::cin);
>
> char ch;
> while (ms >> ch) { // WHY NO WARNING?
> std::cout << ch << '\n';
> }
> return 0;
> }
>
> //================= end of go.cpp ======================================
>
> Compile with:
> c++ -std=c++11 -o go go.cpp
>
> To "fix" the program:
> Change declaration in main from
> char ch;
> to
> std::string ch;
>
> Why no warning?
> Thanks.
I get a warning:
$ /usr/local/bin/g++ -c -Wall -Wextra -pedantic -Weffc++ -std=c++11 63458.cc
63458.cc: In function ‘int main()’:
63458.cc:29:12: warning: ‘ch’ may be used uninitialized in this function
[-Wmaybe-uninitialized]
while (ms >> ch) { // WHY NO WARNING?
~~~^~~~~
$
(In reply to Marek Polacek from comment #4)
> Yeah, shifting booleans is a weird thing to do. So is multiplication or
> dividing booleans - and we don't warn on that either.
Yeah I'd expect -Wbool-operation to catch it, but it doesn't. So confirmed that
-Wbool-operation could be improved.
