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* [Bug c++/17022] New: Behavior of out-of-range enums
@ 2004-08-13 22:59 igodard at pacbell dot net
2004-08-13 23:45 ` [Bug c++/17022] " pinskia at gcc dot gnu dot org
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: igodard at pacbell dot net @ 2004-08-13 22:59 UTC (permalink / raw)
To: gcc-bugs
I'm pretty sure that the behavior of:
#include <iostream>
enum A{a,b,c};
enum B{d,e,f,g};
int main() {
std::cerr << A(3) << ":" << B(4) << "\n";
return 0;
}
is implementation defined by the standard, but the actual result:
~/ootbc/members/members/sweetie/test/src$ a.out
3:0
is quite startling. Are you sure that this is what you want the implementation to define?
Ivan
--
Summary: Behavior of out-of-range enums
Product: gcc
Version: 3.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: igodard at pacbell dot net
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17022
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/17022] Behavior of out-of-range enums
2004-08-13 22:59 [Bug c++/17022] New: Behavior of out-of-range enums igodard at pacbell dot net
@ 2004-08-13 23:45 ` pinskia at gcc dot gnu dot org
2004-08-14 3:58 ` bangerth at dealii dot org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2004-08-13 23:45 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2004-08-13 23:45 -------
Yes this is what we want but we should warn about this see PR 12242 for which I marking this as a dup
of.
*** This bug has been marked as a duplicate of 12242 ***
--
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |DUPLICATE
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17022
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/17022] Behavior of out-of-range enums
2004-08-13 22:59 [Bug c++/17022] New: Behavior of out-of-range enums igodard at pacbell dot net
2004-08-13 23:45 ` [Bug c++/17022] " pinskia at gcc dot gnu dot org
@ 2004-08-14 3:58 ` bangerth at dealii dot org
2004-08-14 5:23 ` igodard at pacbell dot net
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: bangerth at dealii dot org @ 2004-08-14 3:58 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From bangerth at dealii dot org 2004-08-14 03:58 -------
The size of a variable of enum type is exactly the number of bits needed
to represent the largest member of the enum (so that you can bit-or
elements). The result therefore makes perfect sense.
W.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17022
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/17022] Behavior of out-of-range enums
2004-08-13 22:59 [Bug c++/17022] New: Behavior of out-of-range enums igodard at pacbell dot net
2004-08-13 23:45 ` [Bug c++/17022] " pinskia at gcc dot gnu dot org
2004-08-14 3:58 ` bangerth at dealii dot org
@ 2004-08-14 5:23 ` igodard at pacbell dot net
2004-08-14 6:11 ` pinskia at gcc dot gnu dot org
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: igodard at pacbell dot net @ 2004-08-14 5:23 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From igodard at pacbell dot net 2004-08-14 05:23 -------
Well, the size thinh mentioned by bangaerth was what I had assumed from the behavior, but it doesn't really explain *all* the behavior. Consider:
#include <iostream>
enum A{a,b,c};
enum B{d,e,f,g};
int main() {
int three = 3;
int four = 4;
std::cerr << A(three) << ":" << A(3) << "!" << B(four) <<":" << B(4) << "\n"
;
return 0;
}
That gets you:
~/ootbc/members/members/sweetie/test/src$ a.out
3:3!4:0
So I have re-opened this as a bug, in that the constant-expression result is not the same as the run-time result. This seems to call for more than a warning, even if it is implementation-defined.
Ivan
--
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |UNCONFIRMED
Resolution|DUPLICATE |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17022
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/17022] Behavior of out-of-range enums
2004-08-13 22:59 [Bug c++/17022] New: Behavior of out-of-range enums igodard at pacbell dot net
` (2 preceding siblings ...)
2004-08-14 5:23 ` igodard at pacbell dot net
@ 2004-08-14 6:11 ` pinskia at gcc dot gnu dot org
2004-08-14 6:16 ` pinskia at gcc dot gnu dot org
2004-08-14 11:51 ` igodard at pacbell dot net
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2004-08-14 6:11 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2004-08-14 06:11 -------
Actually it is not undefined or implementation defined by the standard, it is unspecified which is a
totally different ball game and we just define it as constants do the get anded, likewise with
optimization where you can prove that the variable is a constant. Otherwise it is the same value as
before this change.
See: <http://www.devx.com/tips/Tip/12684> for unspecified vs. undefined
Also see PR 15330 where we defined the defintion of what we want to be able to do which I am going
to mark as a dup of.
*** This bug has been marked as a duplicate of 15330 ***
--
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |DUPLICATE
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17022
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/17022] Behavior of out-of-range enums
2004-08-13 22:59 [Bug c++/17022] New: Behavior of out-of-range enums igodard at pacbell dot net
` (3 preceding siblings ...)
2004-08-14 6:11 ` pinskia at gcc dot gnu dot org
@ 2004-08-14 6:16 ` pinskia at gcc dot gnu dot org
2004-08-14 11:51 ` igodard at pacbell dot net
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2004-08-14 6:16 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pinskia at gcc dot gnu dot org 2004-08-14 06:15 -------
Oh by the way, we don't have to document unspecified behavior, ref: <http://www.embedded.com/
shared/printableArticle.jhtml?articleID=9900563>. This is constrast to implementation defined
behavior.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17022
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c++/17022] Behavior of out-of-range enums
2004-08-13 22:59 [Bug c++/17022] New: Behavior of out-of-range enums igodard at pacbell dot net
` (4 preceding siblings ...)
2004-08-14 6:16 ` pinskia at gcc dot gnu dot org
@ 2004-08-14 11:51 ` igodard at pacbell dot net
5 siblings, 0 replies; 7+ messages in thread
From: igodard at pacbell dot net @ 2004-08-14 11:51 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From igodard at pacbell dot net 2004-08-14 11:51 -------
How about at least a warning when you wrap around a constant-expression? For that matter, if it's unspecified can you specify it as an error?
Ivan
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17022
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2004-08-14 11:51 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2004-08-13 22:59 [Bug c++/17022] New: Behavior of out-of-range enums igodard at pacbell dot net
2004-08-13 23:45 ` [Bug c++/17022] " pinskia at gcc dot gnu dot org
2004-08-14 3:58 ` bangerth at dealii dot org
2004-08-14 5:23 ` igodard at pacbell dot net
2004-08-14 6:11 ` pinskia at gcc dot gnu dot org
2004-08-14 6:16 ` pinskia at gcc dot gnu dot org
2004-08-14 11:51 ` igodard at pacbell dot net
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