http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44500
--- Comment #18 from Gunther Piez 2011-03-24 11:45:47 UTC
---
I have chosen the "recommended" way and added a cast, -fpermissive would allow
to many other dubious constructs to pass. Still I think c++ should get rid of
implicit integer con
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44500
Jason Merrill changed:
What|Removed |Added
Status|SUSPENDED |RESOLVED
Resolution|
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44500
--- Comment #16 from Jason Merrill 2011-03-24
08:58:46 UTC ---
The committee closed my DR as not a defect. We could still downgrade this
error to a pedwarn, though.
http://www.open-std.org/JTC1/SC22/WG21/docs/cwg_closed.html#1078
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jason at gcc dot gnu dot org changed:
What|Removed |Added
Status|NEW |SUSPENDED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44500
--
jason at gcc dot gnu dot org changed:
What|Removed |Added
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Last reconfirm
--- Comment #15 from jason at gcc dot gnu dot org 2010-07-09 21:29 ---
I agree that this is a bug, but it's a bug in C++0x, not with GCC, and
unfortunately it came up too late for me to include it as a national body
comment. I have submitted it as a defect report.
--
jason at gcc do
--- Comment #14 from redi at gcc dot gnu dot org 2010-06-13 17:14 ---
(In reply to comment #12)
> Why not make -Wconversion an error, at least this would
> be consistent ;-)
You can use -Werror=conversion
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44500
--- Comment #12 from gpiez at web dot de 2010-06-12 08:46 ---
I am closing this, as it isn't a gcc bug, as it behaves according to the
standard.
The bug is in the standard, as it mandates
f<1,1> // ok
f() // error
g() // no error, but undefined behaviuour
f(char, ch
--- Comment #13 from gpiez at web dot de 2010-06-12 08:47 ---
...
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gpiez at web dot de changed:
What|Removed |Added
Status|UNCONFIRMED |RESO
--- Comment #11 from redi at gcc dot gnu dot org 2010-06-11 14:56 ---
(In reply to comment #9)
> I understand now after the implicit promotion to int of a non constant value
> the result of the narrowing operation can't be guaranteed to fit in the
> original type. But I still think it sh
--- Comment #10 from manu at gcc dot gnu dot org 2010-06-11 13:33 ---
(In reply to comment #8)
>
> In both cases, T+T has type int,
We know that, but I don't think most C/C++ programmers know about integer
promotion rules. We just disagree here. But since this is mandated by the
stand
--- Comment #9 from gpiez at web dot de 2010-06-11 13:27 ---
I understand now after the implicit promotion to int of a non constant value
the result of the narrowing operation can't be guaranteed to fit in the
original type. But I still think it shouldn't give an error, and if the
standa
--- Comment #8 from redi at gcc dot gnu dot org 2010-06-11 13:20 ---
(In reply to comment #7)
> He is referring to a testcase like:
>
> template void f() {
> struct A {
> T x;
> };
>
> T y = 42;
> A a = { y + C };
> }
>
> int main() {
> f();
> f();
> }
>
> So, we warn
--- Comment #7 from manu at gcc dot gnu dot org 2010-06-11 13:07 ---
He is referring to a testcase like:
template void f() {
struct A {
T x;
};
T y = 42;
A a = { y + C };
}
int main() {
f();
f();
}
So, we warn for T == char but not for T == int. I know that the standa
--- Comment #6 from redi at gcc dot gnu dot org 2010-06-11 12:51 ---
(In reply to comment #5)
> So is it provable that for a "T op T" to be stored in T no narrowing takes
> place?
Yes, if the values are constants.
> If the answer for T == char is no and for T == int it is yes this is r
--- Comment #5 from gpiez at web dot de 2010-06-11 12:09 ---
So is it provable that for a "T op T" to be stored in T no narrowing takes
place?
If the answer for T == char is no and for T == int it is yes this is rather
fishy ;-)
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44500
--- Comment #4 from redi at gcc dot gnu dot org 2010-06-11 11:42 ---
(In reply to comment #2)
> Sorry for the unicode mess. The error> I believe I should not get an error,
> even if the template parameter type is
> larger than a char, as long as the template parameter value fits in in c
--- Comment #3 from redi at gcc dot gnu dot org 2010-06-11 11:37 ---
'y' and 'C' are both promoted to int and 'y' is not a constant, so the
resulting value cannot be proven to fit in a char, so it's a narrowing
conversion.
If you make 'y' a const int then the value y+C is a constant and
--- Comment #2 from gpiez at web dot de 2010-06-11 11:34 ---
Sorry for the unicode mess. The error message is 'error: narrowing conversion
of "(((int)y) + 1)" from "int" to "char" inside { }'.
The same error happens with a non templated function, but if I use two template
parameters, th
--- Comment #1 from manu at gcc dot gnu dot org 2010-06-11 10:57 ---
I wonder what the C++ standard said because we have the same issue in
Wconversion and Joseph rejected my patch arguing that the operation was done in
the larger type, so there was a narrowing conversion. I still believe
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