[CMake] Adding definitions to compile one file ?

[Vania Joloboff]

Hi

I want to add two definitions to compile one specific files
in addition to the global definitions.
I have the following problem. If I use

set_source_files_properties(source.cpp
PROPERTIES
COMPILE_DEFINITIONS VAR1=${MY_VAR1} VAR2=${MY_VAR2} )

then I get error message incorrect number of arguments for 
set_source_files_properties

If I put
set_source_files_properties(source.cpp
PROPERTIES COMPILE_DEFINITIONS "VAR1=${MY_VAR1} VAR2=${MY_VAR2}" )

then it generates strangely enough the compile command

/usr/bin/c++ -DVAR1="path1 VAR2=path2" ... source.cpp

with the double quotes as above, which gives a weird value to VAR1 and 
no value to VAR2

If I use twice set_source_files_properties
the first one is overwritten by the second
and I only get the definition of VAR2

What am I supposed to do ?

Thankx

PS I am using cmake 3.2.2 on Linux Mint.