Conditionally link to shared library on a define in qmake

Question

I have a code which is branched by #define directive, for example:

#ifdef USE_LIB_CRYPTO
#include <openssl/evp.h>
#else
#include <cryptopp/pwdbased.h>
#include <cryptopp/sha.h>
#endif

Depending on is defined USE_LIB_CRYPTO or not I should add

LIBS += -lcrypto

or

LIBS += -lcryptopp

How can I do that? For example, this should be controlled by:

qmake ./ DEFINES+="USE_LIB_CRYPTO"

So I need to somehow check is define passed to qmake and link to the library I need.

Always add the lib dependency. If it is not necessary, linker make the job for you. — LPs, Sep 23 '16 at 07:33
@LPs if I link to a library which does not exist on the build machine I get `/usr/bin/ld: cannot find -lsdfjiijasdf` so I think this should be controlled. — VP., Sep 23 '16 at 07:37
BTW you can use `CONFIG` like shown into [this answer](http://stackoverflow.com/a/14458172/3436922) — LPs, Sep 23 '16 at 07:46

score 2 · Accepted Answer · answered Sep 23 '16 at 08:02

2

You can use contains test function of the qmake.

contains ( DEFINES, USE_LIB_CRYPTO ){
    LIBS += -lcrypto
} else {
    LIBS += -lcryptopp
}

answered Sep 23 '16 at 08:02

HeyYO

1 Answers1