Building Qt for Linux x86 with fontconfig support

Question

I'm porting my Qt app to Linux for x86 architecture, and since the last official release for that platform is 5.5, I'm trying to do my own build of Qt 5.11.3. I want to use fontconfig to enable use of system fonts. My build platform is Centos 7.5, and I'm using a GCC toolchain which builds x86 binaries with -m32 switch. The problem is, I can't get it to see the fontconfig library. I've installed it with the package fontconfig-devel-2.13.0-4.3.el7.i686

When running configure with the option -fontconfig, I get the following error message:

ERROR: Feature 'fontconfig' was enabled, but the pre-condition '!config.win32 && features.system-freetype && libs.fontconfig' failed.

My understanding from this is that I have to use -system-freetype and can't use -qt-freetype, but when I try that (also with -feature-freetype), I get this message:

ERROR: Feature 'system-freetype' was enabled, but the pre-condition 'features.freetype && libs.freetype' failed.

The relevant messages in config.log are:

looking for library freetype
Trying source 0 (type pkgConfig) of library freetype ...
pkg-config use disabled globally.
  => source produced no result.
Trying source 1 (type freetype) of library freetype ...
+ cd /home/myuser/qt-build/config.tests/freetype && /home/myuser/qt-build/qtbase/bin/qmake "CONFIG -= qt debug_and_release app_bundle lib_bundle" "CONFIG += shared warn_off console single_arch" -early "CONFIG += cross_compile" 'LIBS += -lfreetype' /home/myuser/qt-build/config.tests/freetype
+ cd /home/myuser/qt-build/config.tests/freetype && MAKEFLAGS= /usr/bin/gmake
> g++ -c -m32 -pipe -O2 -std=gnu++11 -w -fPIC  -I. -I/home/myuser/qt-everywhere-src-5.11.3/qtbase/mkspecs/linux-g++-32 -o main.o main.cpp
> main.cpp:2:22: fatal error: ft2build.h: No such file or directory
>  #include <ft2build.h>
>                       ^
> compilation terminated.
> gmake: *** [main.o] Error 1
 => source failed verification.
test config.qtbase_gui.libraries.freetype FAILED

Now, I do also get this message:

WARNING: Cross compiling without sysroot. Disabling pkg-config

which I understand is the source of the "source 0" failure. I have however tried to point configure manually point it to the freetype include directory, by passing FREETYPE_INCDIR=/usr/include/freetype2 to configure; however, as can be seen in the log file, the value does not seem to be used when detecting freetype.

Am I missing a trick here, or are the configure scripts broken? And if it's the latter, is there a way to work around this?

EDIT: For completeness, the environment for running configure:

CFLAGS=-m32
CXXFLAGS=-m32 --std=c++1x

Configure flags:

-opensource
-xplatform linux-g++-32
-nomake tests -nomake examples -nomake tools
-prefix /home/myuser/qt_install/
-qpa xcb
-no-use-gold-linker
-icu ICU_PREFIX=/home/myuser/icu_install ICU_LIBS="-licui18n -licuuc -licudata"
-no-opengl
-fontconfig -feature-freetype -system-freetype FREETYPE_INCDIR=/usr/include/freetype2

Can you compile & link a minimum C-program (with -m32) that links to freetype? Can you share the parameters with which you invoked the configure script? Note that compiling x86 from x86_64 hosts is cross-compiliation, doing that requires different configure-parameters than a native build (which is probably why pkg-config is disabled). — markus-nm
I can build and link a minimal C program that links to freetype if I supply -I/usr/include/freetype2 switch so that it can find the ft2build header - which in the context of Qt configuration I was hoping to achieve with FREETYPE_INCDIR=/usr/include/freetype2 - but it does not appear to work as evidenced in the log excerpt. — AndrzejJ

AndrzejJ AndrzejJ · Accepted Answer · 2018-12-14T15:10:34

I've found it's possible to work around this by setting CPATH (and LIBRARY_PATH to point at a specific build of Freetype which it turned out I needed as well). It looks like the fact that FREETYPE_* variables are ignored when detecting the presence of Freetype is indeed a bug in the config scripts.

Building Qt for Linux x86 with fontconfig support

2 Answers