SimultaneousVariantBuilds

This page demonstrates how to tell SCons to build multiple variants of your software all at the same time, for example:

debug and release versions
host and target versions

SConstruct:

   1 release_env = Environment(CCFLAGS = ['-O2'])
   2 debug_env = release_env.Copy(CCFLAGS = ['-g'])
   3 
   4 SConscript('src/SConscript', build_dir='release', exports={'env':release_env})
   5 SConscript('src/SConscript', build_dir='debug', exports={'env':debug_env})

src/SConscript:

   1 Import('env')
   2 env.Program('hello', ['hello.c'])

Output:

$ scons
gcc -g -c -o debug/hello.o debug/hello.c
gcc -o debug/hello debug/hello.o
gcc -O2 -c -o release/hello.o release/hello.c
gcc -o release/hello release/hello.o

Here's the same sort of thing for windows using the Microsoft C++ compiler. In the SConstruct:

   1 base_env = Environment(tools = ["msvc", "mslink"])
   2 
   3 # Build different variants:
   4 for flavour in ["Debug", "Release"]:
   5     env = base_env.Copy()
   6     
   7     # Set up compiler and linker flags:
   8     if flavour == "Debug":
   9         # Use debug multithreaded DLL runtime, and no optimization
  10         env.Append(CCFLAGS = ["/MDd", "/Od"])
  11         # Each object has its own pdb, so -jN works
  12         env.Append(CCFLAGS = ["/Zi", "/Fd${TARGET}.pdb"])
  13         env.Append(LINKFLAGS = ["/DEBUG"])
  14     else:
  15         # Use multithreaded DLL runtime, and some sensible amount of optimization
  16         env.Append(CCFLAGS = ["/MD", "/Ox"])
  17 
  18     # Call the SConstruct for each subproject.
  19     SConscript(
  20             "hello/SConscript",
  21             exports = ["env"],
  22             build_dir = flavour + "/hello",
  23             duplicate = 0,
  24             )
  25     SConscript(
  26             "world/SConscript",
  27             exports = ["env"],
  28             build_dir = flavour + "/world",
  29             duplicate = 0,
  30             )

And this is the contents of hello/SConscript:

   1 # Make sure we don't change the imported environment by mistake:
   2 Import("env")
   3 imported_env = env
   4 env = env.Copy()
   5 
   6 # Set up things for this project
   7 env.AppendUnique(CPPPATH = ["."])
   8 
   9 hello_t = env.Program(
  10         target = "hello",
  11         source = ["hello.c"],
  12         )

And the output:

scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
cl /nologo /MDd /Od /Zi /FdDebug\hello\hello.obj.pdb /IDebug\hello /Ihello /c hello\hello.c /FoDebug\hello\hello.obj hello.c
link /nologo /DEBUG /OUT:Debug\hello\hello.exe Debug\hello\hello.obj
cl /nologo /MD /Ox /IRelease\hello /Ihello /c hello\hello.c /FoRelease\hello\hello.obj hello.c
link /nologo /OUT:Release\hello\hello.exe Release\hello\hello.obj
...
scons: done building targets.

Thanks to Werner Schiendl for posting this solution to the mailing list.