The placeholders for std::tr1::bind are defined in an anonymous namespace, which means they have internal linkage. This will cause ODR violations when used in function templates (such as std::tr1::bind) from multiple translation units. Although probably harmless (every definition will generate identical code, even if technically ill-formed) we can avoid the ODR violations by reusing the std::placeholder objects as the std::tr1::placeholder objects. To make this work, the std::_Placeholder type needs to be defined for C++98 mode, so that <tr1/functional> can use it. The members of the std::placeholder namespace must not be defined by <functional> in C++98 mode, because "placeholders", "_1", "_2" etc. are not reserved names in C++98. Instead they can be declared in <tr1/functional>, because those names *are* reserved in that header. With the std::placeholders objects declared, a simple using-directive suffices to redeclare them in namespace std::tr1::placeholders. This means any use of the TR1 placeholders actually refers to the C++11 placeholders, which are defined with external linkage and exported from the library, so don't cause ODR violations. libstdc++-v3/ChangeLog: * include/std/functional (std::_Placeholder): Define for C++98 as well as later standards. * include/tr1/functional (std::placeholders::_1 etc): Declare for C++98. (tr1::_Placeholder): Replace with using-declaration for std::_Placeholder. (tr1::placeholders::_1 etc.): Replace with using-directive for std::placeholders. |
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config | ||
doc | ||
include | ||
libsupc++ | ||
po | ||
python | ||
scripts | ||
src | ||
testsuite | ||
ChangeLog | ||
ChangeLog-1998 | ||
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ChangeLog-2019 | ||
Makefile.am | ||
Makefile.in | ||
README | ||
acinclude.m4 | ||
aclocal.m4 | ||
config.h.in | ||
configure | ||
configure.ac | ||
configure.host | ||
crossconfig.m4 | ||
fragment.am | ||
linkage.m4 |
README
file: libstdc++-v3/README New users may wish to point their web browsers to the file index.html in the 'doc/html' subdirectory. It contains brief building instructions and notes on how to configure the library in interesting ways.