From 4ae6c2fe91d8dc5bdb7f6d9808b097dde8a8265f Mon Sep 17 00:00:00 2001 From: Boris Kolpackov Date: Thu, 14 Oct 2021 09:06:50 +0200 Subject: Move symbol exporting documentation from NEWS to manual --- doc/manual.cli | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) (limited to 'doc') diff --git a/doc/manual.cli b/doc/manual.cli index d63e887..e941b6b 100644 --- a/doc/manual.cli +++ b/doc/manual.cli @@ -6640,6 +6640,52 @@ otherwise share the same header search paths, for example, as a family of libraries), then the whitelist may not be effective. +\h#cc-auto-symexport|Automatic DLL Symbol Exporting| + +The \c{bin.def} module (automatically loaded by the \c{c} and \c{cxx} modules +for the \c{*-win32-msvc} targets) provides a rule for generating +symbol-exporting \c{.def} files. This allows automatically exporting all +symbols for all the Windows targets/compilers using the following arrangement +(showing for \c{cxx} in this example): + +\ +lib{foo}: libul{foo}: {hxx cxx}{**} ... + +lib{foo}: def{foo}: include = ($cxx.target.system == 'win32-msvc') +def{foo}: libul{foo} + +if ($cxx.target.system == 'mingw32') + cxx.loptions += -Wl,--export-all-symbols +\ + +That is, we use the \c{.def} file approach for MSVC (including when building +with Clang) and the built-in support (\c{--export-all-symbols}) for MinGW. + +Note that it is also possible to use the \c{.def} file approach for MinGW. In +this case we need to explicitly load the \c{bin.def} module (which should be +done after loading \c{c} or \c{cxx}) and can use the following arrangement: + +\ +# root.build + +using cxx +using bin.def +\ + +\ +lib{foo}: libul{foo}: {hxx cxx}{**} ... + +lib{foo}: def{foo}: include = ($cxx.target.class == 'windows') +def{foo}: libul{foo} +\ + +Note also that this only deals with exporting of the symbols from a DLL. In +order to work, code that uses such a DLL should be able to import the symbols +without explicit \c{__declspec(dllimport)} declarations. This works thanks +to the symbol auto-importing support in Windows linkers. Note, however, that +auto-importing only works for functions and not for global variables. + + \h#cc-gcc|GCC Compiler Toolchain| The GCC compiler id is \c{gcc}. -- cgit v1.1