[Bug c++/44499] No default constructor available
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499 Jackie Rosen jackie.rosen at hushmail dot com changed: What|Removed |Added CC||jackie.rosen at hushmail dot com --- Comment #22 from Jackie Rosen jackie.rosen at hushmail dot com --- *** Bug 260998 has been marked as a duplicate of this bug. *** Seen from the domain http://volichat.com Marked for reference. Resolved as fixed @bugzilla.
[Bug c++/44499] No default constructor available
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499 Paolo Carlini paolo.carlini at oracle dot com changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution||WORKSFORME Target Milestone|--- |4.7.0 Summary|[4.7 Regression?] No|No default constructor |default constructor |available |available | --- Comment #21 from Paolo Carlini paolo.carlini at oracle dot com 2011-09-25 14:11:52 UTC --- Oh, indeed. Then I guess this can be simply closed for 4.7.0, the diagnostic issue is now moot.
[Bug c++/44499] No default constructor available
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499 --- Comment #18 from Jonathan Wakely redi at gcc dot gnu.org 2011-03-19 19:56:49 UTC --- (In reply to comment #17) OK, I'll update the changes page with a variation of the note in comment 11, done
[Bug c++/44499] No default constructor available
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499
--- Comment #16 from Ryan Hill dirtyepic at gentoo dot org 2011-03-17
11:36:15 UTC ---
(In reply to comment #11)
GCC 4.4 and 4.5 reject the example too, so I don't know when the bug was
fixed,
it's apparently not a change in 4.6 (though there were some bugs in this area
fixed recently.)
Hmm, that particular example does fail. But we've still been seeing this in
packages such as xulrunner and openjade that are fine with 4.5, so some
variation of the example is a new error. eg. this only fails with 4.6:
struct A { int a; A (); };
struct B : public A { };
const B b;
[Bug c++/44499] No default constructor available
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499
--- Comment #17 from Jonathan Wakely redi at gcc dot gnu.org 2011-03-17
11:45:35 UTC ---
(In reply to comment #16)
(In reply to comment #11)
GCC 4.4 and 4.5 reject the example too, so I don't know when the bug was
fixed,
it's apparently not a change in 4.6 (though there were some bugs in this
area
fixed recently.)
Hmm, that particular example does fail. But we've still been seeing this in
packages such as xulrunner and openjade that are fine with 4.5, so some
variation of the example is a new error. eg. this only fails with 4.6:
struct A { int a; A (); };
struct B : public A { };
const B b;
Yup, that fails with 4.6, as it should. It's also rejected by EDG and Clang,
but not VC++
OK, I'll update the changes page with a variation of the note in comment 11,
but upstream should still read the standard and deal with it ;)
[Bug c++/44499] No default constructor available
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499 --- Comment #13 from Manuel López-Ibáñez manu at gcc dot gnu.org 2011-03-04 10:02:19 UTC --- (In reply to comment #12) Manu, can we close this? @Jonathan I still think that the messages of Comeau and Clang are better than GCC's. I will try for 4.7 to produce a patch to change the message to be like: error: default initialization of const object 'g_d' requires a user-provided default constructor [-fpermissive] note: 'const class D' has no user-provided default constructor Do you agree? (I'd like to keep the note to jump to the declaration of class D). @Piotr,Ryan I started a list of GCC diagnostics in the wiki. http://gcc.gnu.org/wiki/VerboseDiagnostics There is only one but the idea would be to collect in a single place extended explanations and fix-it hints about gcc diagnostics. Perhaps in the future such knowledge can be added to the compiler proper and enabled with a -fdiagnostics-explain or -fdiagnostics-fix-it. I think this could be a killer-feature for GCC to have, but collecting the data is a lot of work for a single person. This is a way to contribute to GCC without writing a single line of code!
[Bug c++/44499] No default constructor available
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499 --- Comment #14 from Jonathan Wakely redi at gcc dot gnu.org 2011-03-04 11:23:41 UTC --- (In reply to comment #13) (In reply to comment #12) Manu, can we close this? @Jonathan I still think that the messages of Comeau and Clang are better than GCC's. I will try for 4.7 to produce a patch to change the message to be like: error: default initialization of const object 'g_d' requires a user-provided default constructor [-fpermissive] note: 'const class D' has no user-provided default constructor Do you agree? Sure, if you still plan to improve it let's definitely keep it open. (I'd like to keep the note to jump to the declaration of class D). Ah yes, that's useful. In the spirit of providing fix it hints, I think the EDG diagnostic is better. There are two ways to avoid the error: 1) Add a default constructor. This changes the type in non-trivial ways with potentially large side-effects in terms of POD-ness, affecting all users of the code and requiring recompilation. It's not even possible for classes defined in third-party headers. 2) Use an initializer. This doesn't change the type and is a purely local change. The second option is probably the right one in most cases :) Expert users who know what they're doing can choose to alter the class, but I don't think we should suggest they do so. How about this: error: Const object 'g_d' requires an initializer [-fpermissive] note: 'const class D' has no user-provided default constructor The error refers to the variable's location and says an initializer is needed. The note refers to the class' location and says it has no default constructor.
[Bug c++/44499] No default constructor available
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499 Jonathan Wakely redi at gcc dot gnu.org changed: What|Removed |Added Keywords||diagnostic Severity|normal |enhancement --- Comment #15 from Jonathan Wakely redi at gcc dot gnu.org 2011-03-04 11:25:01 UTC --- changing Severity and Keywords to clarify the outstanding work is just a diagnostic enhancement
[Bug c++/44499] No default constructor available
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499 Ryan Hill dirtyepic at gentoo dot org changed: What|Removed |Added CC||dirtyepic at gentoo dot org --- Comment #10 from Ryan Hill dirtyepic at gentoo dot org 2011-03-03 22:28:45 UTC --- (In reply to comment #3) (In reply to comment #1) gcc is correct, accepting the code previously was a bug that was fixed recently You need to provide an initializer for g_d This sort of changes should be documented in the changes.html page or in porting_to.html Could this be added? Some upstreams are arguing this is a bug in GCC. In the past we've found that if it's documented that this change was indeed intentional, they're more willing to fix their code.
[Bug c++/44499] No default constructor available
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499
--- Comment #11 from Jonathan Wakely redi at gcc dot gnu.org 2011-03-03
23:14:10 UTC ---
(In reply to comment #10)
(In reply to comment #3)
(In reply to comment #1)
gcc is correct, accepting the code previously was a bug that was fixed
recently
You need to provide an initializer for g_d
This sort of changes should be documented in the changes.html page or in
porting_to.html
I prepared this:
liAs required by the C++ standard, G++ no longer allows objects of
const-qualified type to be default initialized unless the type has a
user-declared default constructor. Code that fails to compile can be
fixed by providing an initializer e.g.
pre
struct S { };
const S s = S();
/pre
Use code-fpermissive/code to allow the old, non-conforming behaviour.
/li
However ...
Could this be added? Some upstreams are arguing this is a bug in GCC. In the
past we've found that if it's documented that this change was indeed
intentional, they're more willing to fix their code.
GCC 4.4 and 4.5 reject the example too, so I don't know when the bug was fixed,
it's apparently not a change in 4.6 (though there were some bugs in this area
fixed recently.)
Upstream will have to accept that G++ (like Clang++ and EDG) conforms to the
standard in this respect.
[Bug c++/44499] No default constructor available
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499 --- Comment #12 from Jonathan Wakely redi at gcc dot gnu.org 2011-03-03 23:16:41 UTC --- Manu, can we close this?
[Bug c++/44499] No default constructor available
--- Comment #7 from manu at gcc dot gnu dot org 2010-07-02 08:09 --- Could someone test what clang says here? Their diagnostics are generally better than g++. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499
[Bug c++/44499] No default constructor available
--- Comment #8 from pluto at agmk dot net 2010-07-02 08:12 --- (In reply to comment #7) Could someone test what clang says here? Their diagnostics are generally better than g++. $ clang++ pr44499.cpp -c pr44499.cpp:5:9: error: default initialization of an object of const type 'D const' requires a user-provided default constructor const D g_d; ^ 1 error generated. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499
[Bug c++/44499] No default constructor available
--- Comment #9 from manu at gcc dot gnu dot org 2010-07-02 09:15 --- Thanks Pawel, which diagnostic do you prefer? I would favor clang's but I would still keep the note that points to the class definition. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499
[Bug c++/44499] No default constructor available
--- Comment #1 from redi at gcc dot gnu dot org 2010-06-11 09:26 --- gcc is correct, accepting the code previously was a bug that was fixed recently You need to provide an initializer for g_d -- redi at gcc dot gnu dot org changed: What|Removed |Added Status|UNCONFIRMED |RESOLVED Resolution||INVALID http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499
[Bug c++/44499] No default constructor available
--- Comment #2 from redi at gcc dot gnu dot org 2010-06-11 10:27 --- A question: apart from quoting chapter and verse from the standard (8.5 [dcl.init], para 9 in C++03, para 6 in C++0x,) how could the diagnostic have been any clearer? It indicates you can use -fpermissive to relax the warning, and it includes a note telling you the type has no user-provided default constructor, which is true. Why would you assume this is a bug, when a developer has gone to the trouble of writing the note? -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499
[Bug c++/44499] No default constructor available
--- Comment #3 from manu at gcc dot gnu dot org 2010-06-11 10:53 --- (In reply to comment #1) gcc is correct, accepting the code previously was a bug that was fixed recently You need to provide an initializer for g_d This sort of changes should be documented in the changes.html page or in porting_to.html -- manu at gcc dot gnu dot org changed: What|Removed |Added CC||manu at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499
[Bug c++/44499] No default constructor available
--- Comment #4 from piotr dot wyderski at gmail dot com 2010-06-11 11:01 --- (In reply to comment #2) A question: apart from quoting chapter and verse from the standard (8.5 [dcl.init], para 9 in C++03, para 6 in C++0x,) how could the diagnostic have been any clearer? It indicates you can use -fpermissive to relax the warning, and it includes a note telling you the type has no user-provided default constructor, which is true. Why would you assume this is a bug, when a developer has gone to the trouble of writing the note? All the compilers I am aware of accept the aforementioned construction, so I blindly assumed that 4.6 is wrong in issuing a warning. The note's content was considered irrelevant, since no error was expected. But if the behaviour is OK, then it is OK no matter what a surprise it turns out to be. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499
[Bug c++/44499] No default constructor available
--- Comment #5 from manu at gcc dot gnu dot org 2010-06-11 11:11 --- Comeau C/C++ 4.3.10.1 (Oct 6 2008 11:28:09) for ONLINE_EVALUATION_BETA2 Copyright 1988-2008 Comeau Computing. All rights reserved. MODE:strict errors C++ C++0x_extensions ComeauTest.c, line 9: error: const variable g_d requires an initializer -- class D has no explicitly declared default constructor const D g_d; ^ ComeauTest.c, line 9: warning: variable g_d was declared but never referenced const D g_d; ^ 1 error detected in the compilation of ComeauTest.c. I think the error message of comeau is better (but our note is better). I will write a patch. -- manu at gcc dot gnu dot org changed: What|Removed |Added Status|RESOLVED|UNCONFIRMED Resolution|INVALID | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499
[Bug c++/44499] No default constructor available
-- manu at gcc dot gnu dot org changed: What|Removed |Added AssignedTo|unassigned at gcc dot gnu |manu at gcc dot gnu dot org |dot org | Status|UNCONFIRMED |ASSIGNED Ever Confirmed|0 |1 Last reconfirmed|-00-00 00:00:00 |2010-06-11 11:11:57 date|| http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499
[Bug c++/44499] No default constructor available
--- Comment #6 from manu at gcc dot gnu dot org 2010-06-11 11:13 --- LLVM is still using GCC in their demo, not Clang. So I cannot test their output. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44499
