I'm trying to link libwebrtc library with Qt application on Windows platform.
I get a lot of linking errors like this:
webrtc.lib(jitter_estimator.obj):-1: error: LNK2038: mismatch detected for 'RuntimeLibrary': value 'MT_StaticRelease' doesn't match value 'MD_DynamicRelease' in ....obj
Apparently this is because the libwebrtc is compiled with -MT (static runtime) buiflag, and Qt application is compiled with -MD flag.
Is it possible to make Qt application compile with -MT? Is it possible to make libwebrtc to compile with -MD ?
Summary of my investigations:
a) It is possible to compile libwebrtc with -MD flags. This is not possible without modifying the sources, but the modification is trivial:
change src/build/config/win/BUILD.gn: in the statement config("default_crt")
replace
#Desktop Windows: static CRT
configs = [":static_crt"]
to
configs = [":dynamic_crt"]
b) It is possible to recompile Qt from sources with -MT -MTd flags.
To do this: edit Src/qtbase/mkspecs/common/msvc-desktop.conf, replace -MD -MDd in this file with -MT -MTd.
configure with option -static.
Both solutions seems to work, at least produce compilable and linkable binaries.
Related
I have a c++ program, which contains two classes. one of them is using libssh and some of its functions and another one is for calculating cpu usage. there is a link of how I a built and added libssh:libssh's functions couldn't be found on qt my program works fine. now I want to build a .so library out of it to use in other programs. first I made two .o file like this:
gcc -c -fPIC info.cpp -o info.o
gcc -c -fPIC cpuusage.cpp -o cpuusage.o
and I made a .so from them:
gcc -shared -o libsmc.so info.o cpuusage.o
whenever I want to use libsmc.so, I include info.h, but the problem is that libssh functions cannot be found. I think I have to add libssh statically to my project. but I don't know how to!
Ps:I read this explanation :Using a shared library in another shared library , but this is for linking shared libraries that have been used in a program via command line, I don't wanna compile program with command line and want to link libraries constantly.
To build a C/C++ software using external libraries, I would really recommend to use a build system instead of typing commands manually.
The most used build system for C++ is CMake (https://cmake.org/), which is well supported by Qt, but there are many other build systems existing. Another is QMake, which is Qt's build system.
If you are using an IDE, like QtCreator or Microsoft Visual Studio, CMake is integrated as well. There are plenty of tutorials and example to use CMake for a project (e.g. https://mirkokiefer.com/cmake-by-example-f95eb47d45b1), even though the learning curve is not as steep as I would want.
But if you still want to use command line (or to debug the command line generated by CMake): When linking against a library, you need to:
Give the include path to the compiler, i.e. the path where the .h of the external library can be found. With gcc, this is done with -I, e.g. "-I/usr/lib/mylib/include".
Give the library folder and name to the linker, i.e. the path where to find the compiled library, as well as its name. With gcc, this is done with -L for the path and -l for the name. Check the gcc manual for more details about these commands.
And if you want to use CMake, then you can use the functions:
target_include_directories(..)
and
target_link_libraries(..)
still facing some strange compilation error while using MSYS2 mingw64 to compile OpenLDAP
I think it boils down to some win socket thing, currently facing 2 major errors during make depend and make
during make depend
cannot locate nt_err.c in servers/slapd/slapi ==> I resorted to copy nt_err.c from libraries/liblber/nt_err.c
Then came the fatal error while make depend in slapi. Command used by make depend: make -w -I/usr/include -I/usr/include -I/usr/include -I/usr/include depend, it maybe because I have passed -I/usr/include in the main make depend
but still
Entering directory '/home/Jimmy/openldapsrc/openldap-2.4.46/servers/slapd/slapi'
../../../build/mkdep -l -d "." -c "cc" -m "-M" -I../../../include -I.. -I. -I../../../include -I./.. -I. plugin.c slapi_pblock.c slapi_utils.c printmsg.c slapi_ops.c slapi_dn.c slapi_ext.c slapi_overlay.c nt_err.c
In file included from slapi_utils.c:34:0:
../../../include/netdb.h:73:10: fatal error: netinet/in.h: No such file or directory
#include <netinet/in.h>
^~~~~~~~~~~~~~
compilation terminated.
And actually I have seen a lot of similar errors, for example during make it will also give error in slapi like
No such file or directory
#include <sys/socket.h>
^~~~~~~~~~~~~~
compilation terminated.
I have checked with pacman -Fs in.h socket.h the output are as follow
msys/msys2-runtime-devel 2.10.0-2
usr/include/cygwin/in.h
usr/include/netinet/in.h
usr/include/sys/socket.h
and I have msys2-runtime-devel installed. Nonetheless this reminded me that during ./configure output contained
checking sys/socket.h usability... no
checking sys/socket.h presence... no
so Ｉ tried to run gcc -xc -E -v - trying to determine what directory is included, however in MSYS2-MINGW64 it stopped at this
COLLECT_GCC=C:\msys64\mingw64\bin\gcc.exe
Target: x86_64-w64-mingw32
Configured with: ../gcc-7.3.0/configure --prefix=/mingw64 --with-local-prefix=/mingw64/local --build=x86_64-w64-mingw32 --host=x86_64-w64-mingw32 --target=x86_64-w64-mingw32 --with-native-system-header-dir=/mingw64/x86_64-w64-mingw32/include --libexecdir=/mingw64/lib --enable-bootstrap --with-arch=x86-64 --with-tune=generic --enable-languages=c,lto,c++,objc,obj-c++,fortran,ada --enable-shared --enable-static --enable-libatomic --enable-threads=posix --enable-graphite --enable-fully-dynamic-string --enable-libstdcxx-time=yes --enable-libstdcxx-filesystem-ts=yes --disable-libstdcxx-pch --disable-libstdcxx-debug --disable-isl-version-check --enable-lto --enable-libgomp --disable-multilib --enable-checking=release --disable-rpath --disable-win32-registry --disable-nls --disable-werror --disable-symvers --with-libiconv --with-system-zlib --with-gmp=/mingw64 --with-mpfr=/mingw64 --with-mpc=/mingw64 --with-isl=/mingw64 --with-pkgversion='Rev1, Built by MSYS2 project' --with-bugurl=https://sourceforge.net/projects/msys2 --with-gnu-as --with-gnu-ld
Thread model: posix
gcc version 7.3.0 (Rev1, Built by MSYS2 project)
COLLECT_GCC_OPTIONS='-E' '-v' '-mtune=generic' '-march=x86-64'
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/cc1.exe -E -quiet -v -iprefix C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/ -D_REENTRANT - -mtune=generic -march=x86-64
the cc1 gave no output, froze MSYS2 and I have to terminate cc1 from task manager.
Then I run directly C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/cc1.exe -E -quiet -v -iprefix C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/ -D_REENTRANT - -mtune=generic -march=x86-64
it returned
ignoring duplicate directory "C:/msys64/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/7.3.0/include"
ignoring nonexistent directory "C:/building/msys64/mingw64/include"
ignoring nonexistent directory "/mingw64/include"
ignoring duplicate directory "C:/msys64/mingw64/lib/gcc/../../lib/gcc/x86_64- w64-mingw32/7.3.0/include-fixed"
ignoring duplicate directory "C:/msys64/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/include"
ignoring nonexistent directory "C:/building/msys64/mingw64/x86_64-w64-mingw32/include"
#include "..." search starts here:
#include <...> search starts here:
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/include
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64- mingw32/7.3.0/../../../../include
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/include-fixed
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/7.3.0/../../../../x86_64-w64-mingw32/include
End of search list.
Turns out the #include <...> search does not include the /usr/include directory of MSYS2, should have been C:/msys64/mingw64/bin/../../usr/include
I tried putting ENV CFLAGS="-I/usr/include" before ./configure, that caused more errors, many .h not usable but presence. and sys/socket.h is usable and presence.
So turns out -I/usr/include somehow did not pass into the compiler?
My Question is, is this configurable? Or is there something wrong with my setup?
OpenLDAP 2.4.46
MSYS2 20161025
MSYS2 has three different toolchains with different purposes:
The msys-2.0.dll-based toolchain, which creates executables that use the POSIX emulation capabilities provided by msys-2.0.dll. The main compiler is /usr/bin/gcc and it uses headers from /usr/include. This is the toolchain to use if your program was written for a Linux or another POSIX-type operating system and you are finding it difficult to port it to Windows because it uses a lot of features not supported by Microsoft.
MinGW 32-bit toolchain. This compiles native Windows software that can run on 32-bit or 64-bit versions of Windows. The main compiler is /mingw32/bin/gcc. To use this toolchain you must launch MSYS2 with the "MinGW-w64 32-bit Shell" shortcut or launch mingw32.exe. This toolchain is not compatible with the headers in /usr/include, but it can use native Windows headers with interfaces defined by Microsoft, like windows.h.
MinGW 64-bit toolchain. This toolchain is just like the 32-bit toolchain except the executables are 64-bit executables, and thus only work on 64-bit Windows. It has its own shortcut in the start menu, and can also be launched with mingw64.exe.
I don't know anything about OpenLDAP, but if it is requiring a bunch of headers that the MinGW toolchains don't have, you could either try to port it to Windows or switch over to building it with the msys-2.0.dll-based toolchain.
I am using qmake to cross-compile my ARM based program on Ubuntu. I have ran into the multithreading issue as described in this thread:
C++ 11 Threads, Error Pure virtual function called
One answer suggests adding the flag to the compilation as:
g++ -pthread -std=c++11 -D__GCC_HAVE_SYNC_COMPARE_AND_SWAP_{1,2,4} thread1.cpp
I am not sure how to add this -D__GCC_HAVE_SYNC_COMPARE_AND_SWAP_{1,2,4} in my qmake project file.
I did QMAKE_CXXFLAGS += -D__GCC_HAVE_SYNC_COMPARE_AND_SWAP_{1,2,4}. My error still remains so I wanted to confirm if this is the right way to add that flag.
It's a bash glob/wildcard. Expands to
-D__GCC_HAVE_SYNC_COMPARE_AND_SWAP_1 -D__GCC_HAVE_SYNC_COMPARE_AND_SWAP_2 -D__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
My problem is related to the one discussed here:
Is there a way that OpenMP can operate on Qt spanwed threads?
Upon trying to run my Qt-based program under Mac OS that has an OpenMP clause in a secondary thread, it crashed. After browsing through the web, now I understand that it is caused by a bug in the rather old version (4.2) of gcc supplied by Apple.
Then I downloaded the latest 4.6 version of gcc from http://hpc.sourceforge.net and tried to compile the project, but I got the following errors from g++ compiler:
unrecognized option ‘-arch’
unrecognized option ‘-Xarch_x86_64’
I learned that this is because these are options, which can be only interpreted by the custom-configured Apple-gcc compiler, but not by standard gcc.
Could anybody please help me could I overcome this issue and configure g++ 4.6 to use with Qt in order to get a bug-free OpenMP support? I admit that I'm a newbie under Mac OS platform with regard to compilers and programming and would like to port my code from Visual Studio-Qt environment.
Many thanks in advance!
If you aren't afraid of messing with your Qt installation, then change the QMAKE_CFLAGS_X86_64 entry in ~/QtSDK/Desktop/Qt/4.8.1/gcc/mkspecs/common/g++-macx.conf.
Replace ‘-Xarch_x86_64’ with ‘-arch x86_64’.
You can use your non-Apple gcc v4.6 and compile a binary for each architecture you want to build (use --target=${ARCH} should be fine for i386 and x86_64). Then once you have a binary for each of the architectures use lipo like so:
lipo -create -arch i386 binary_32bit -arch x86_64 binary_64bit -output binary_universal
This will create a fat binary (aka universal binary) named binary_universal from binary_32bit and binary_64bit.
Or you could use clang/llvm instead of gcc, which probably won't have the bug you described and (if supplied via Apple's developer tools) should be able to compile universal binaries directly.
You should run qmake woth corresponding -spec option, for example, to use gcc46 on freebsd it is needed to run qmake so:
qmake --spec=freebsd-g++46
Lipo can indeed be used to put multiple object files together into a "fat" object file, in fact it turns out this is just what apple's compiler does. Their GCC compiler is actually a driver that maps various architectures to the appropriate compiler for the architecture and then mashes the objects together using lipo.
see: http://lists.macosforge.org/pipermail/macports-dev/2011-September/016210.html
Here is the source file for that driver:
http://opensource.apple.com/source/gcc/gcc-5666.3/driverdriver.c
All one needs to do to get a new version of GCC to honor the -arch flag is to modify this driver and get it to point to a script wrapper for your version of gcc that adds the appropriate flags for the given architecture and then passes all the rest of the arguments. Something like this:
#!/bin/sh
/opt/local/bin/gcc-mp-4.6 -m32 $#
and
#!/bin/sh
/opt/local/bin/gcc-mp-4.6 -m64 $#
Here is a link that talks about how to do it, and provides a cmake project to easily get the macports version of GCC fixed up and supporting the -arch flag for the two intel architectures:
http://thecoderslife.blogspot.com/2015/07/building-with-gcc-46-and-xcode-4.html
After I successfully implemented my first JVMTI agent and the building completes with the g++ compiler I want to go over integrate the building process into my Qt project.
However I am facing some build process configuration issues:
The parameters I would run with the g++ compiler looks like this:
g++ -fPIC -shared agent.cpp -o libagent.so -I /usr/lib/jvm/java-6-openjdk/include -I /usr/lib/jvm/java-6-openjdk/include/linux
This works very well. Now to qmake:
I am aware of the parameter CXXFLAGS to add further parameters to the C++ compiler used by qmake, but how can I convert this parametrized compiler call into qmake?
With the help of Qt Undocumented qmake I figured out a custom configuration in qmake. However, it is not flawless, it produces now a libagent.so and a agent.o which is not needed.
SOURCES_AGENT = agent.cpp
agent.name = agent
agent.input = SOURCES_AGENT
agent.dependency_type = TYPE_C
agent.variable_out = OBJECTS
agent.output = libagent.so
agent.commands = $${QMAKE_CXX} $(CXXFLAGS) -fPIC -shared -o libagent.so $(INCPATH) ${QMAKE_FILE_IN}
QMAKE_EXTRA_COMPILERS += agent
I don't know the specific answer but...
As JVMTI agents are "usually" headless are you using qmake because your project has a head that you are developing in kdevelop/qtcreator? Is the head using the attach API?
If not and it is purely headless then would not a different editor/cmake be better? qmake is now a preproc for cmake, for the MOC stuff, no?
I must admit I'm a bit fuzzy on q/cmake although I'm hoping to move to cmake for my work.