Cmake Qt5 | undefined reference to `QPrinter::QPrinter(QPrinter::PrinterMode)

Question

I am preparing cmake build for qt application. where I am using following structure ..

libMyApp which uses

SET(QT5_MODULES Widgets PrintSupport Netw         


        

Answer 1

The order of the entries in the function TARGET_LINK_LIBRARIES() is important. The libraries with no dependecies shall be mentioned last which are typically some standard libraries or external libraries, in this example the Qt5 Libs.

An example:

• Application depends
• Lib_A depends on Lib_B and Lib_std
• Lib_B depends on Lib_std
• Lib_std has no dependencies

Then the call of the function shall be the following:

TARGET_LINK_LIBRARIES(
    ${TARGET_NAME}   # Name of the app
    "Lib_A"
    "Lib_B"
    "Lib_std"        # Last entries: Std Libs, external Libs, ...
)

In this application I assumed that ${CODE_LIB_FILES}=libMyApp.a has some dependencies to the Qt5-Libs so it would be plausible to move this entry above the Qt5-Libs.

SET(QT5_MODULES Widgets PrintSupport XmlPatterns)
FIND_PACKAGE(Qt5 REQUIRED COMPONENTS ${QT5_MODULES})

TARGET_LINK_LIBRARIES(
    ${TARGET_NAME}
    ${CODE_LIB_FILES}       # <<< Moved this entry up
    Qt5::Widgets
    Qt5::PrintSupport 
    Qt5::XmlPatterns
)