Make cmake pass command line variable to compiler

Question

I have following code:

int main() {
#ifdef COMMIT_VERSION
   cout << "app version: " << COMMIT_VERSION << endl;
#endif
}

I would like to invoke cmake such that it passes COMMIT_VERSION variable defined on command line to g++ and thus to my application. E.g. following invocation:

cmake -WHAT_IS_THE_OPTION_NAME COMMIT_VERSION='"Hello Version"'
make
./a.out

produces output

app version: Hello Version

You probably want the [`configure_file`](http://www.cmake.org/cmake/help/v3.0/command/configure_file.html) function. — Drew McGowen, Aug 08 '14 at 16:05
Due to quite convoluted build system. I would prefer not to use files just command line argument passing. — Trismegistos, Aug 08 '14 at 16:08
Perhaps related (or a duplicate): http://stackoverflow.com/q/7900661/417197 — André, Aug 11 '14 at 05:51

score 14 · Accepted Answer · answered Aug 08 '14 at 16:13

14

You can use the -D <var>:<type>=<value> option to add a definition within the cmake script (type and value being optional), like so:

cmake -D COMMIT_VERSION='"whatever version here"' ...

Then, inside the script, you can use the add_definitions function to pass the definition to g++:

add_definitions(-DCOMMIT_VERSION=${COMMIT_VERSION})

answered Aug 08 '14 at 16:13

Drew McGowen

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Using this solution I would have to provide COMMIT_VERSION to cmake as I previously wanted. It turned out that it would be more suitable if I could provide COMMIT_VERSION to make instead of cmake. Is it possible with cmake? – Trismegistos Aug 11 '14 at 09:31

Make cmake pass command line variable to compiler

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