qmake eval function "always true" for string literals

Question

For our build machines, I want to have conditional pre-processor defines in my project based on environment variables at the time of compilation. the environment string is "MY_CUSTOM_BUILD", and based on its value, I'd like to add defines.

My project file has something like:

_MY_CUSTOM_BUILD = $$(MY_CUSTOM_BUILD)

eval(_MY_CUSTOM_BUILD = $$"AAA") {
    DEFINES+= MY_CUSTOM_BUILD_AAA
}

eval(_MY_CUSTOM_BUILD = $$"BBB") {
    DEFINES+= MY_CUSTOM_BUILD_BBB
}

However, in the code, it seems that "MY_CUSTOM_BUILD_AAA" and "MY_CUSTOM_BUILD_BBB" are ALWAYS defined regardless of whether the environment string exists, or its value.

#ifdef MY_CUSTOM_BUILD_AAA
 Blah();    <--- this code always compiles regardless.
#endif

#ifdef MY_CUSTOM_BUILD_BBB
 Blah2();    <--- this code always compiles regardless.
#endif

Am I doing something wrong with the syntax?

Answer 1

So, yes. what I ended up doing was this:

contains(_MY_CUSTOM_BUILD, "AAA") {
    DEFINES+= MY_CUSTOM_BUILD_AAA
}

instead of that:

eval(_MY_CUSTOM_BUILD = $$"AAA") {
    DEFINES+= MY_CUSTOM_BUILD_AAA
}

and it worked.