Instructions for building libsigc++ on Visual Studio
====================================================
Building the libsigc++ on Windows is now supported using Visual Studio
versions 2017 or later in both 32-bit and 64-bit (x64) flavors,
via NMake Makefiles.  Due to C++-17 usage, Visual Studio 2015 or
earlier is not supported, and any use of the headers installed with
this package will require the use of the /std:c++17 compiler flag.

libsigc++ itself has no external dependencies, but building the
benchmark test program will require an installation of the Boost
C++ libraries.

The following describes what items are built with the following
targets:

-all (or no target specified): The libsigc++ DLL and the example programs.
-examples: The libsigc++ DLL and the example programs.
-tests: The libsigc++ DLL and the test programs.
-benchmark: The libsigc++ DLL and the benchmark program.

Building directly from a GIT checkout is now supported, provided that a PERL
installation is present (pass the PERL interpreter executable in your NMake
command line by using 'PERL=<path_to_PERL_interpreter_executable>' by using
the 'prep-git-build' target.  Note that in this case, the 'prep-git-build'
target needs to be run before building any of the other targets.

The following are instructions for performing such a build.  A 'clean' target is
provided-it is recommended that one cleans the build and redo the build if any
configuration option changed.  An
'install' target is also provided to copy the built items in their appropriate
locations under $(PREFIX), which is described below.

Invoke the build by issuing the command:
nmake /f Makefile.vc CFG=[release|debug] [PREFIX=...] <option1=1 option2=1 ...>
where:

CFG: Required.  Choose from a release or debug build.  Note that
     all builds generate a .pdb file for each .dll and .exe built--this refers
     to the C/C++ runtime that the build uses.

PREFIX: Optional.  Base directory of where the third-party headers, libraries
        and needed tools can be found, i.e. headers in $(PREFIX)\include,
        libraries in $(PREFIX)\lib and tools in $(PREFIX)\bin.  If not
        specified, $(PREFIX) is set as $(srcroot)\..\vs$(X)\$(platform), where
        $(platform) is win32 for 32-bit builds or x64 for 64-bit builds, and
        $(X) is the short version of the Visual Studio used, as follows:
        2017: 15

USE_COMPAT_LIBS: Build the sigc++ DLL and .lib with the filename
                 'sigc-vc150(d)-3_0' for all builds.  This is for
                 compatibility reasons, if re-building dependent code is not
                 convenient, for instance

Explanation of options, set by <option>=1:
------------------------------------------
BOOST_DLL: When building the benchmark, link to a DLL build of the Boost
           libraries.  Required if your installation of the Boost libraries
           are built as DLLs.  Note that debug builds must link to debug
           builds of Boost and release builds must link to release builds
           of Boost.