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* [Bug c++/61856] New: Ternary operator in an NSDMI causes double evaluation
@ 2014-07-20 12:18 ville.voutilainen at gmail dot com
2014-07-20 12:19 ` [Bug c++/61856] " redi at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: ville.voutilainen at gmail dot com @ 2014-07-20 12:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61856
Bug ID: 61856
Summary: Ternary operator in an NSDMI causes double evaluation
Product: gcc
Version: 4.10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ville.voutilainen at gmail dot com
First test:
#include <iostream>
#ifdef OK
struct ostream { } cout;
bool operator<<(ostream&, const char* s)
{ __builtin_printf("%s", s); return true; }
#else
using std::cout;
#endif
struct X { int a = (cout<<"hmm\n") ? 1 : 2;};
int main()
{
X x;
}
With -DOK, this prints "hmm" once, otherwise it prints "hmm" twice. This
suggested
that perhaps the problem is specific to iostream, but wrapping the NSDMI into
a lambda fixes the double evaluation:
#include <iostream>
#ifdef OK
struct ostream { } cout;
bool operator<<(ostream&, const char* s)
{ __builtin_printf("%s", s); return true; }
#else
using std::cout;
#endif
struct X { int a = ([]{return bool(cout<<"hmm\n");}()) ? 1 : 2;};
int main()
{
X x;
}
Simpler cases like just incrementing a global variable in the ternary
operator seem to work fine:
#include <iostream>
int global_x = 0;
struct X { int a = (global_x++) ? 1 : 2;};
int main()
{
X x;
std::cout << global_x << std::endl;
}
Perhaps this is some weird gimplification bug.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/61856] Ternary operator in an NSDMI causes double evaluation
2014-07-20 12:18 [Bug c++/61856] New: Ternary operator in an NSDMI causes double evaluation ville.voutilainen at gmail dot com
@ 2014-07-20 12:19 ` redi at gcc dot gnu.org
2015-06-18 16:50 ` miyuki at gcc dot gnu.org
2015-06-21 9:06 ` ville.voutilainen at gmail dot com
2 siblings, 0 replies; 4+ messages in thread
From: redi at gcc dot gnu.org @ 2014-07-20 12:19 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61856
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2014-07-20
Ever confirmed|0 |1
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/61856] Ternary operator in an NSDMI causes double evaluation
2014-07-20 12:18 [Bug c++/61856] New: Ternary operator in an NSDMI causes double evaluation ville.voutilainen at gmail dot com
2014-07-20 12:19 ` [Bug c++/61856] " redi at gcc dot gnu.org
@ 2015-06-18 16:50 ` miyuki at gcc dot gnu.org
2015-06-21 9:06 ` ville.voutilainen at gmail dot com
2 siblings, 0 replies; 4+ messages in thread
From: miyuki at gcc dot gnu.org @ 2015-06-18 16:50 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61856
Mikhail Maltsev <miyuki at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |miyuki at gcc dot gnu.org
--- Comment #1 from Mikhail Maltsev <miyuki at gcc dot gnu.org> ---
It seems that this bug was fixed in r224533 (PR58063).
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug c++/61856] Ternary operator in an NSDMI causes double evaluation
2014-07-20 12:18 [Bug c++/61856] New: Ternary operator in an NSDMI causes double evaluation ville.voutilainen at gmail dot com
2014-07-20 12:19 ` [Bug c++/61856] " redi at gcc dot gnu.org
2015-06-18 16:50 ` miyuki at gcc dot gnu.org
@ 2015-06-21 9:06 ` ville.voutilainen at gmail dot com
2 siblings, 0 replies; 4+ messages in thread
From: ville.voutilainen at gmail dot com @ 2015-06-21 9:06 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61856
Ville Voutilainen <ville.voutilainen at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |DUPLICATE
--- Comment #2 from Ville Voutilainen <ville.voutilainen at gmail dot com> ---
Fixed by the resolution of PR58063.
*** This bug has been marked as a duplicate of bug 58063 ***
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2015-06-21 9:06 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2014-07-20 12:18 [Bug c++/61856] New: Ternary operator in an NSDMI causes double evaluation ville.voutilainen at gmail dot com
2014-07-20 12:19 ` [Bug c++/61856] " redi at gcc dot gnu.org
2015-06-18 16:50 ` miyuki at gcc dot gnu.org
2015-06-21 9:06 ` ville.voutilainen at gmail dot com
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