>>643
すみません、ワーニングをコピペします。

g++.exe "C:\MinGW\Learn\Learn2\template_ostream.cpp" -o "C:\MinGW\Learn\Learn2\template_ostream.exe" -Wall -s -O3 -I"C:\mingw\include" -I"C:\mingw\include\c++" -I"C:\mingw\include" -L"C:\mingw\lib"
C:/MinGW/Learn/Learn2/template_ostream.cpp:10: warning: friend declaration `
std::ostream& operator<<(std::ostream&, const A<T>&)' declares a
non-template function
C:/MinGW/Learn/Learn2/template_ostream.cpp:10: warning: (if this is not what
you intended, make sure the function template has already been declared and
add <> after the function name here) -Wno-non-template-friend disables this
warning

Execution terminated
Compilation successful