msbuild: set a specific preprocessor #define in the command line

Question

In a C++ file, I have a code like this:

#if ACTIVATE
#   pragma message( "Activated" )
#else
#   pragma message( "Not Activated")
#endif

I want to set this ACTIVE define to 1 with the msbuild command line.

It tried this but it doesn't work:

msbuild /p:DefineConstants="ACTIVATE=1"

Any idea?

Answer 1

I think you want:

/p:DefineConstants=ACTIVATE

Answer 2

It should probably be:

#ifdef ACTIVATE
#   pragma message( "Activated" )
#else
#   pragma message( "Not Activated")
#endif

Answer 3

C++ projects (and solutions) are not (yet ?) integrated in the MSBuild environment. As part of the build process, the VCBuild task is called, which is just a wrapper around vcbuild.exe.

You could :

• create a specific configuration for your solution where ACTIVATE=1 would be defined, and compile it with devenv.exe (with the /ProjectConfig switch).
• create your own target file to wrap your own call to the VCBuild task (see the Override parameter)...
• use vcbuild.exe instead of msbuild.exe. (vcbuild.exe does not seem to have the equivalent of an Override parameter).

Note that your solution would not work for C# projects either unless you tweaked your project files a bit. For reference, here is how I would do this :

• Add the following code before the call to <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" /> :

<PropertyGroup Condition=" '$(MyConstants)' != '' ">
  <DefineConstants>$(DefineConstants);$(MyConstants)</DefineConstants>
</PropertyGroup>

• Call MSBuild like this :

msbuild /p:MyConstants="ACTIVATE=1"

Answer 4

The answer is : YOU CANNOT

Answer 5

I needed to do this too - needed to be able to build two different versions of my app and wanted to be able to script the build using VCBUILD. VCBUILD does have the /override command line switch, but I am not sure it can be used to modify #define symbols that can then be tested using #if conditional compilation.

The solution I cam up with was to write a simple utility to create a header file that #defined the symbol based on the state of an environment variable and run the utility from a pre-build step. Prior to each execution of the VCBUILD step the script sets the environment variable and "touches" a file in the app to ensure that the prebuild step is executed.

Yes, it is an ugly hack, but it was the best I could come up with!

Answer 6

Is there specific documentation of this somewhere? I know there are several references that can be used to "connect the dots"(MSBuild Wiki & VS10 announcments), but I need something very clear and concise.

Answer 7

This is a duplicate of this or this.