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(gcc-295.info)Deprecated Features

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Deprecated Features
===================

   In the past, the GNU C++ compiler was extended to experiment with new
features, at a time when the C++ language was still evolving. Now that
the C++ standard is complete, some of those features are superceded by
superior alternatives. Using the old features might cause a warning in
some cases that the feature will be dropped in the future. In other
cases, the feature might be gone already.

   While the list below is not exhaustive, it documents some of the
options that are now deprecated:

`-fthis-is-variable'
     In early versions of C++, assignment to this could be used to
     implement application-defined memory allocation. Now, allocation
     functions (`operator new') are the standard-conforming way to
     achieve the same effect.

`-fexternal-templates'
`-falt-external-templates'
     These are two of the many ways for g++ to implement template
     instantiation. Note: Template Instantiation. The C++ standard
     clearly defines how template definitions have to be organized
     across implementation units. g++ has an implicit instantiation
     mechanism that should work just fine for standard-conforming code.