[scope_exit] C++11 freely uses typename (on MSVC10?)
Hi all, Isn't it C++11 supposed to allow to use typename freely even outside type-dependent context? Does MSVC10 support this? For example, is the following supposed to compile on MSVC10? #include <boost/mpl/identity.hpp> int main() { typedef typename boost::mpl::identity<int>::type t; t i = 0; return i; } Note: Using typename freely will allow me to not introduce SCOPE_EXIT_ALL_TPL and still support this_ (not just this). Thanks. --Lorenzo -- View this message in context: http://boost.2283326.n4.nabble.com/boost-scope-exit-C-11-freely-uses-typenam... Sent from the Boost - Dev mailing list archive at Nabble.com.
Lcaminiti wrote on Monday, April 02, 2012 1:53 PM
For example, is the following supposed to compile on MSVC10? #include <boost/mpl/identity.hpp>
int main() { typedef typename boost::mpl::identity<int>::type t; t i = 0; return i; }
This code does not compile on my copy of MSVC10. -->error C2899: typename cannot be used outside a template declaration Erik ---------------------------------------------------------------------- This message w/attachments (message) is intended solely for the use of the intended recipient(s) and may contain information that is privileged, confidential or proprietary. If you are not an intended recipient, please notify the sender, and then please delete and destroy all copies and attachments, and be advised that any review or dissemination of, or the taking of any action in reliance on, the information contained in or attached to this message is prohibited. Unless specifically indicated, this message is not an offer to sell or a solicitation of any investment products or other financial product or service, an official confirmation of any transaction, or an official statement of Sender. Subject to applicable law, Sender may intercept, monitor, review and retain e-communications (EC) traveling through its networks/systems and may produce any such EC to regulators, law enforcement, in litigation and as required by law. The laws of the country of each sender/recipient may impact the handling of EC, and EC may be archived, supervised and produced in countries other than the country in which you are located. This message cannot be guaranteed to be secure or free of errors or viruses. References to "Sender" are references to any subsidiary of Bank of America Corporation. Securities and Insurance Products: * Are Not FDIC Insured * Are Not Bank Guaranteed * May Lose Value * Are Not a Bank Deposit * Are Not a Condition to Any Banking Service or Activity * Are Not Insured by Any Federal Government Agency. Attachments that are part of this EC may have additional important disclosures and disclaimers, which you should read. This message is subject to terms available at the following link: http://www.bankofamerica.com/emaildisclaimer. By messaging with Sender you consent to the foregoing.
Nelson, Erik - 2 wrote
Lcaminiti wrote on Monday, April 02, 2012 1:53 PM
For example, is the following supposed to compile on MSVC10? #include <boost/mpl/identity.hpp>
int main() { typedef typename boost::mpl::identity<int>::type t; t i = 0; return i; }
This code does not compile on my copy of MSVC10.
-->error C2899: typename cannot be used outside a template declaration
Thanks. Is anyone positive about what the C++11 standard says in this case? This code compiles on my GCC 4.5.3 with -std=c++0x... who's right MSVC or GCC? Thanks a lot. --Lorenzo -- View this message in context: http://boost.2283326.n4.nabble.com/boost-scope-exit-C-11-freely-uses-typenam... Sent from the Boost - Dev mailing list archive at Nabble.com.
Le 02/04/12 22:04, lcaminiti a écrit :
Nelson, Erik - 2 wrote
Lcaminiti wrote on Monday, April 02, 2012 1:53 PM
For example, is the following supposed to compile on MSVC10? #include<boost/mpl/identity.hpp>
int main() { typedef typename boost::mpl::identity<int>::type t; t i = 0; return i; } This code does not compile on my copy of MSVC10.
-->error C2899: typename cannot be used outside a template declaration
Thanks. Is anyone positive about what the C++11 standard says in this case? This code compiles on my GCC 4.5.3 with -std=c++0x... who's right MSVC or GCC?
I don't know what the c++11 standard says, but as there are some compilers that don't support it and this was not allowed on C++03 compilers you should live with this constraint and the use of typename outside templates. Best, Vicente
For example, is the following supposed to compile on MSVC10? #include <boost/mpl/identity.hpp>
int main() { typedef typename boost::mpl::identity<int>::type t; t i = 0; return i; }
This code does not compile on my copy of MSVC10.
-->error C2899: typename cannot be used outside a template declaration
Thanks. Is anyone positive about what the C++11 standard says in this case? This code compiles on my GCC 4.5.3 with -std=c++0x... who's right MSVC or GCC?
C++03 section 14.2 paragraph 5 says: "[Note: just as is the case with the typename prefix, the template prefix is allowed in cases where it is not strictly necessary; i.e., when the expression on the left of the -> or ., or the nested-name-specifier is not dependent on a template-parameter.]" C++11 amends this to: "[Note: As is the case with the typename prefix, the template prefix is allowed in cases where it is not strictly necessary; i.e., when the nested-name-specifier or the expression on the left of the -> or . is not dependent on a template-parameter, or the use does not appear in the scope of a template.]" The addition of "or the use does not appear in the scope of a template" makes your example valid in C++11 (but it was invalid in C++03). It seems recent versions of GCC have adopted the C++11 behaviour, but MSVC has not (yet, as of version 10). Regards, Nate
Nathan Ridge wrote
For example, is the following supposed to compile on MSVC10? #include <boost/mpl/identity.hpp>
int main() { typedef typename boost::mpl::identity<int>::type t; t i = 0; return i; }
This code does not compile on my copy of MSVC10.
-->error C2899: typename cannot be used outside a template declaration
Thanks. Is anyone positive about what the C++11 standard says in this case? This code compiles on my GCC 4.5.3 with -std=c++0x... who's right MSVC or GCC?
C++03 section 14.2 paragraph 5 says:
"[Note: just as is the case with the typename prefix, the template prefix is allowed in cases where it is not strictly necessary; i.e., when the expression on the left of the -> or ., or the nested-name-specifier is not dependent on a template-parameter.]"
C++11 amends this to:
"[Note: As is the case with the typename prefix, the template prefix is allowed in cases where it is not strictly necessary; i.e., when the nested-name-specifier or the expression on the left of the -> or . is not dependent on a template-parameter, or the use does not appear in the scope of a template.]"
The addition of "or the use does not appear in the scope of a template" makes your example valid in C++11 (but it was invalid in C++03).
It seems recent versions of GCC have adopted the C++11 behaviour, but MSVC has not (yet, as of version 10).
I see. Thanks. --Lorenzo -- View this message in context: http://boost.2283326.n4.nabble.com/boost-scope-exit-C-11-freely-uses-typenam... Sent from the Boost - Dev mailing list archive at Nabble.com.
participants (4)
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lcaminiti -
Nathan Ridge -
Nelson, Erik - 2 -
Vicente J. Botet Escriba