Where in Qt Creator do I pass arguments to a compiler? - c++

Question

Where in Qt Creator do I pass arguments to a compiler?
It isn't really that obvious.

Answer 1

Depending on your build system it's either in your qmake project file(.pro, standard for new projects) or in one of the CMake files (CMakeLists.txt, used by KDE and several other projects).
Using .pro:
QMAKE_CXXFLAGS += -O2
Using CMake:
set( CMAKE_CXX_FLAGS "-g -Wall")

Answer 2

To add compiler flags, open your .pro file and add a line like this:
QMAKE_CXXFLAGS += -std=c++0x
For standard flags like debug vs. release etc. you should try to use the predefined qmake options (see QMake documentation) for the sake of platform and compiler-independency, as QMake will map them to the compiler-specific flags.

Answer 3

If your intention is to precompile some source code you can do like this:
/A/ In your .pro file you can add a line like this:
DEFINES += HOPLA
/B/ In you .cpp or .h file you can use it like this
#ifdef HOPLA
// Do something
#else
// Do something different
#endif

Answer 4

for C projects, add the following line in .pro file
QMAKE_CFLAGS += -std=c99

Answer 5

in the .pro file you can add variables which modify the make behavior for example, if you try to execute the following command:
g++ -Wall -I/usr/include/cppconn -o exe main.cpp -L/usr/lib -lmysqlcppconn
you must add the following lines in the .pro file
INCLUDEPATH += /usr/include/cppconn
LIBS += -L/usr/lib -lmysqlcppconn
Check the image below.
For more information on the available variables that QT IDE uses, you can visit the following link where they explain in more detail each one. Qt Documentation: Variables

Answer 6

As the elected answer points, for CMake based projects, you can edit the CMakeLists.txt and set the flags for the compiler, and for this case, I have a pictorial demonstration on how to add flags on QtCreator/CMake.
I wanted to add the '-pedantic' flag, which warns about extensions, without throwing errors while executing the program, and here's pictorial example of how to enable compiler flags on CMake while using QtCreator:
For more context:
On the example below, I'm setting the size of a Static Array at Runtime, something that is only possible with Variable-length Array feature, which is available at C99, but defined as optional feature starting from C11. Without -pedantic flag being available for the compiler, the warning would't be displayed after compiling the code.