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Diffstat (limited to 'contrib/gcc/doc/compat.texi')
| -rw-r--r-- | contrib/gcc/doc/compat.texi | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/contrib/gcc/doc/compat.texi b/contrib/gcc/doc/compat.texi index 3e4ef89..3c2931b 100644 --- a/contrib/gcc/doc/compat.texi +++ b/contrib/gcc/doc/compat.texi @@ -113,3 +113,44 @@ interpretations of the C++ ABI by different vendors, bugs in the ABI, or bugs in the implementation of the ABI in different compilers. GCC's @code{-Wabi} switch warns when G++ generates code that is probably not compatible with the C++ ABI@. + +The C++ library used with a C++ compiler includes the Standard C++ +Library, with functionality defined in the C++ Standard, plus language +runtime support. The runtime support is included in a C++ ABI, but there +is no formal ABI for the Standard C++ Library. Two implementations +of that library are interoperable if one follows the de-facto ABI of the +other and if they are both built with the same compiler, or with compilers +that conform to the same ABI for C++ compiler and runtime support. + +When G++ and another C++ compiler conform to the same C++ ABI, but the +implementations of the Standard C++ Library that they normally use do not +follow the same ABI for the Standard C++ Library, object files built with +those compilers can be used in the same program only if they use the same +C++ library. This requires specifying the location of the C++ library +header files when invoking the compiler whose usual library is not being +used. The location of GCC's C++ header files depends on how the GCC +build was configured, but can be seen by using the G++ @option{-v} option. +With default configuration options for G++ 3.2 the compile line for a +different C++ compiler needs to include + +@example + -I@var{gcc_install_directory}/include/c++/3.2 +@end example + +Similarly, compiling code with G++ that must use a C++ library other +than the GNU C++ library requires specifying the location of the header +files for that other library. + +The most straightforward way to link a program to use a particular +C++ library is to use a C++ driver that specifies that C++ library by +default. The @command{g++} driver, for example, tells the linker where +to find GCC's C++ library (@file{libstdc++}) plus the other libraries +and startup files it needs, in the proper order. + +If a program must use a different C++ library and it's not possible +to do the final link using a C++ driver that uses that library by default, +it is necessary to tell @command{g++} the location and name of that +library. It might also be necessary to specify different startup files +and other runtime support libraries, and to suppress the use of GCC's +support libraries with one or more of the options @option{-nostdlib}, +@option{-nostartfiles}, and @option{-nodefaultlibs}. |
