SDL's own Visual C++ 2010+ projects will typically fail to build, if and when they are included via a custom, Visual Studio Solution file (.sln).  The errors generated are all due to SDL being unable to find its own header files.


Here is some sample build-output:

------ Build started: Project: SDL2, Configuration: Debug Win32 ------
  e_atan2.c
c:\users\davidl\documents\code\sdl\sdl\src\libm\../SDL_internal.h(34): fatal error C1083: Cannot open include file: 'SDL_config.h': No such file or directory
  e_log.c
c:\users\davidl\documents\code\sdl\sdl\src\libm\../SDL_internal.h(34): fatal error C1083: Cannot open include file: 'SDL_config.h': No such file or directory
  e_pow.c
c:\users\davidl\documents\code\sdl\sdl\src\libm\../SDL_internal.h(34): fatal error C1083: Cannot open include file: 'SDL_config.h': No such file or directory
  e_rem_pio2.c


... and so on ...

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The build errors can be fixed by modifying SDL's own Visual C++ 2010+ project files, telling them to look for its header files in a directory relative to the MSVC project.  As of this writing, using the latest SDL code from hg.libsdl.org/SDL (which is at changeset 9858 / 6d6a972746b3 / http://hg.libsdl.org/SDL/rev/6d6a972746b3 ), has SDL looking for its header files relative to SDL's own VS .sln file.

This bug can make it tricky to build customized, or development versions of SDL, as part of another app.

A patch is forthcoming, one which simply changes SDL's primary .vcxproj files to use '$(ProjectDir)', rather than '$(SolutionDir)', in order to locate SDL's public headers.  This change should allow SDL to continue building via it's own .sln file (in VisualC/SDL.sln), as well as via external, custom .sln files.