Including libtiff.pri gets error "Could not find feature system-zlib"

aibo

Dear All,

I'm using Qt 5.9.3 on Windows, and trying to use LibTiff by including "3rdparty/libtiff.pri" in my .pro file.

# MyProject.pro
include($$(QTDIR)/../Src/qtimageformats/src/3rdparty/libtiff.pri)

It was possible to use LibTiff by this way in Qt 5.7.0.
However in Qt 5.9.3, qmake gets "Could not find feature system-zlib" error.

"libtiff.pri" includes "zlib_dependency.pri", and it seems "zlib_dependency.pri" causes the error.

#libtiff.pri
INCLUDEPATH += $$PWD/libtiff/libtiff
SOURCES += \
    $$PWD/libtiff/libtiff/tif_aux.c \
    ...
    $$PWD/libtiff/port/snprintf.c

win32:        SOURCES += $$PWD/libtiff/libtiff/tif_win32.c
else:         SOURCES += $$PWD/libtiff/libtiff/tif_unix.c
android:      SOURCES += $$PWD/libtiff/port/lfind.c

include($$PWD/zlib_dependency.pri)

# zlib_dependency.pri
qtConfig(system-zlib) {
    QMAKE_USE_PRIVATE += zlib
} else {
    QT_PRIVATE += zlib-private
}

Has anyone know how to solve this problem?

Pablo J. Rogina

@aibo said in including libtiff.pri gets error "Could not find feature system-zlib":

qtConfig(system-zlib) {

IMO it's telling you that Qt will use system provided zlib. So you need to install zlib in your OS. More information about Qt configuration options here.

aibo

This post is deleted!

aibo

@Pablo-J.-Rogina

Thank you for your suggestion, but it seems I need to build Qt source code with -system-zlib option.
For many various reasons, I would like to use prebuilt Qt binaries...

The only solution I found is to modify "zlib_dependency.pri" like this.

#qtConfig(system-zlib) {
contains(QT_CONFIG, system-zlib) { // same as Qt 5.7.0's zlib_dependency.pri
QMAKE_USE_PRIVATE += zlib
} else {
QT_PRIVATE += zlib-private
}

Qt 5.7.0 used "contains" instead of "qtConfig", and it worked fine.
By modifying Qt 5.9.3's zlib_dependency.pri in the same way, the error has been disappeared.
But if you know other better solutions, let me know please.