[Bug libstdc++/91653] ostream::operator<<(streambuf*) should fail the ostream when write output stream error but not

2020-01-29 Thread redi at gcc dot gnu.org 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91653

Jonathan Wakely  changed:

   What|Removed |Added

 Status|WAITING |RESOLVED
 Resolution|--- |INVALID

--- Comment #7 from Jonathan Wakely  ---
Yes, closing.

[Bug libstdc++/91653] ostream::operator<<(streambuf*) should fail the ostream when write output stream error but not

2020-01-29 Thread marxin at gcc dot gnu.org 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91653

Martin Liška  changed:

   What|Removed |Added

 Status|UNCONFIRMED |WAITING
   Last reconfirmed||2020-01-29
 CC||marxin at gcc dot gnu.org,
   ||redi at gcc dot gnu.org
 Ever confirmed|0   |1

--- Comment #6 from Martin Liška  ---
@Jonathan: Can we close this as invalid?

[Bug libstdc++/91653] ostream::operator<<(streambuf*) should fail the ostream when write output stream error but not

2019-10-02 Thread lh_mouse at 126 dot com 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91653

Liu Hao  changed:

   What|Removed |Added

 CC||lh_mouse at 126 dot com

--- Comment #5 from Liu Hao  ---
This may be inconsistency (if not necessarily a defect) in the C++ standard,
since both `basic_ostream::{put,write}`, as UnformattedOutputFunctions, set
`badbit` in case of output failure, but `operator<<(basic_streambuf*)` doesn't.
Nevertheless GCC is doing the right thing and conform to all standards.

It should also be noted that if `operator<<(basic_streambuf*)` could not
extract any character, `failbit` is set on the output stream. Thus correct use
of this function requires a loop, as follows:

```
bool copy_stream(std::ostream& os, std::istream& is)
  {
while(os && (is.rdbuf()->sgetc()
 != std::istream::traits_type::eof()))
  os << is.rdbuf();
return !!os;
  }
```

Anyway, it is not a bug in libstdc++.

[Bug libstdc++/91653] ostream::operator<<(streambuf*) should fail the ostream when write output stream error but not

2019-09-10 Thread yhliang86 at hotmail dot com 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91653

--- Comment #4 from yinghui  ---
(In reply to TC from comment #3)
> Looks NAD to me.
> 
> http://eel.is/c++draft/ostream.inserters#8.2 doesn't say that we set any bit
> in that case. Contrast with http://eel.is/c++draft/ostream.unformatted#3 and
> http://eel.is/c++draft/ostream.unformatted#5.2

so, seems like this is a bug of the c++ standard?
if an i/o function can't report failure on i/o operation failure, it can not be
used in any serious code.

[Bug libstdc++/91653] ostream::operator<<(streambuf*) should fail the ostream when write output stream error but not

2019-09-09 Thread rs2740 at gmail dot com 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91653

TC  changed:

   What|Removed |Added

 CC||rs2740 at gmail dot com

--- Comment #3 from TC  ---
Looks NAD to me.

http://eel.is/c++draft/ostream.inserters#8.2 doesn't say that we set any bit in
that case. Contrast with http://eel.is/c++draft/ostream.unformatted#3 and
http://eel.is/c++draft/ostream.unformatted#5.2

[Bug libstdc++/91653] ostream::operator<<(streambuf*) should fail the ostream when write output stream error but not

2019-09-08 Thread yhliang86 at hotmail dot com 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91653

--- Comment #2 from yinghui  ---
(In reply to Jonathan Wakely from comment #1)
> GCC 4.9.2 has been unsupported for several years.

but both the code and the problem still keeps exactly the same.

I have seen many c++ code write 'os << is.rdbuf()` as a stream copy idiom, and
this may silently write corrupted data in case like disk full.

[Bug libstdc++/91653] ostream::operator<<(streambuf*) should fail the ostream when write output stream error but not

2019-09-04 Thread redi at gcc dot gnu.org 
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91653

--- Comment #1 from Jonathan Wakely  ---
GCC 4.9.2 has been unsupported for several years.