C++11: template parameter redefines default argument

问题

When compiling the following source code with gcc there are no errors / warnings:

template< typename T = int > T func( );
template< typename T = int > T func( );

When I compile the same source code with clang++, I got the following error:

redeftempparam.cc:2:24: error: template parameter redefines default argument
template< typename T = int > T func( );
                       ^
redeftempparam.cc:1:24: note: previous default template argument defined here
template< typename T = int > T func( );
                       ^
1 error generated.

Command to compile

[clang++|g++] -Wall -Werror -std=c++11 redeftempparam.cc

(Version information: gcc 4.7.2, clang version 3.3 (trunk 171722))

My question:

Is this type of redefinition allowed? If not: can you please point me to the appropriate point in the C++ standard?

回答1:

§14.1.12:

A template-parameter shall not be given default arguments by two different declarations in the same scope.

[Example:

template<class T = int> class X;
template<class T = int> class X { /∗... ∗/ }; // error

— end example ]

来源：https://stackoverflow.com/questions/14197436/c11-template-parameter-redefines-default-argument