I was about to archive for the OTA distribution with Xcode 4 when Xcode is suddenly giving me the infamous preprocessor or lexical issue. This did not happen on the build nor release configuration settings both on the device and the simulator.
I used my own static library with the angle-bracket style import. Pardon me, but Im not quite sure wether that can cause the problems.
#import <MyCommonLib/headerfile.h>
On my static library project, I put all of the header on the public section and it is placed nicely on the DerrivedData shared folder for the build result (checked), and I have put the dependencies of my main project to depend on the static library project, also I have linked the static library with my main project.
Any idea of what can cause this only to happen when I am archiving it? (it tested great with both my device and simulator).
Cheers,
This error is due to some "imported" files no longer be found / referenced by compiler ( possibly "Deleted", either delete from disk / delete reference only).
Try to change:
#import<MyCommonLib/headerfile.h>
to:
#import "MyCommonLib/headerfile.h"
Make sure the file exist as well.
Related
I am writing a typical Qt (4.8.2) app with plugins. One of the plugins includes a couple custom interfaces, by calling the Q_INTERFACE macro. Those interfaces are found in .h files visible to the project (via the .pro includes) and they all contain a macro call to Q_DECLARE_INTERFACES.
Yet upon compiling the moc file I get an undefined interface error in the main .h file of the plugin. It doesn't tell me which though, it only specifies the line of the first (I tried changing the order but it makes no difference - unless all interfaces are affected - heck, who knows, that could be the case.)
This plugin works at other people's desks. Some of the stuff in the main app is written with Qt 5 but always with macros to check for the version and include other code for earlier versions like mine. This also works at other people's desks who work with 4.8.2 for their plugins.
Where to look for the cause of that error ?
I don't know why my question got voted down, but here's the answer :
With the copy of the project I also received the moc_*.cpp files and some files called mocinclude.tmp . This was a first git add mistake.
But there is another problem : at least the latter (if not the former) does not get cleaned properly or recreated by Qmake/make clean.
A third problem : In mocinclude.tmp there were absolute file paths from the computer where the project was first created, which wasn't mine. Relative paths would have been less error-prone.
Those wrong absolute paths led to the "undefined interface" error (which is nothing less but a "file not found" error in the case of a needed interface file) when compiling the moc files.
Deleting all mocinclude.tmp (and moc files) solved my problem.
(I also made sure to tell git to not track them anymore.)
I'm running JetBrains ReSharper 8.2 on a project that uses SASS for styling.
I compile my seperate scss files into one file "common.css". This file is not included in the project, but gets compiled on build on the server (grunt + compass takes care of this).
I don't want to include this file, but only my SCSS files in the project. This however causes ReSharper to report a lot of errors ("Unknown CSS class"...) in my views because the file isn't included.
Is there a workaround for this (without disabling css errors in settings)?
I've tried the "ReSharper.ExternalCode" extension (https://resharper-plugins.jetbrains.com/packages/ReSharper.ExternalCode), but without any luck.
Sadly, there isn't a workaround for this. ReSharper doesn't know about SCSS files, and doesn't know anything about files that aren't included in the project, so it can only assume the CSS classes are undefined.
The external code plugin should work and allow ReSharper to process the resulting css file. However, I'm not sure how flexible it is - I think it needs everything to be configured before the solution is opened. That is, it only tells ReSharper about the generated file when the solution is being opened. Configuring things while a solution is open probably won't be reflected immediately (but I haven't tried it). Similarly, it doesn't notify ReSharper of changes to the file, and I don't think that ReSharper sets up any monitoring. So if the file isn't available when the solution opens, or changes while it's open, ReSharper won't have correct information. I'd try and configure it, close the solution and reopen.
I use QtCreator + mingw.
I have compiled QSQLITE2 plugin. I simply entered plugin directory in Qt source code:
c:\Qt\Qt5.2.0\5.2.0\Src\qtbase\src\plugins\sqldrivers\sqlite
and I built it with my sqlite 2.8.17 that I have locally (as dll and header):
qmake "LIBS+=-Lc:\projects\lib -lsqlite" "INCLUDEPATH+=c:\projects\include"
make
make install
Everything builds okay.
Now, I have another DLL (also implemented as Qt plugin, a custom one), which makes use of QSQLITE2 Qt plugin. My own dll is also linked to sqlite.dll. So it looks like this:
my.dll depends on sqlite.dll
%QT_PLUGINS%\qsqlite2d.dll depends on sqlite.dll
my.dll uses qsqlite2d.dll through Qt's plugin engine
myApp.exe loads my.dll
Problem is that my application cannot load my.dll, because of invalid location access or something like that. I don't know any details and that's the problem.
The sqlite.dll is in the application directory when running it.
When I run application in debug mode, it crashes in some assembly file, but in stack trace I can see that it's somewhere inside sqlite.dll, in sqlite_step symbol. That's all I know.
Note 1) I have another plugin dll, the my3.dll, which uses QSQLITE plugin (it's for sqlite3) and is linked with sqlite3.dll and this one loads just fine. I have compiled QSQLITE plugin myself as well (even there was the one provided with Qt, that's because Qt linked statically to sqlite3 and I wanted it to link dynamically to sqlite3.dll).
Note 2) Both plugins work just fine under Linux.
Any hints what might be wrong? What else can I check?
EDIT:
I've just performed a test: I deleted my.dll from plugins to avoid loading it at all. Then I added code to main.cpp:
QSqlDatabase::addDatabase("QSQLITE2", ":memory:");
Thing is, that it also crashed, with the very same stack trace (at this very line, I debugged it). Thus I think there's something wrong with sqlite2 Qt plugin, but I'm still unable to tell what. I looked up for other sqlite.dll, I just downloaded the one from sqlite.org: http://www.sqlite.org/sqlitedll-2_8_17.zip - so it's official build, but it's the exactly the same file I had and it also fails the same way.
It turned out that qsqlite2d.dll cannot be linked sqlite.dll, because sqlite.dll is not compiled in debug mode. After recompiling application in release mode (thus using qsqlite2.dll, not qsqlite2d.dll), the plugin loads correctly and works.
This makes sense, but just one more thing that bugs me - qsqlited.dll (for sqlite3) had no problem linking with sqlite3.dll. No matter if I compiled debug or release - the single sqlite3.dll worked with both debug and release plugins. Anyone has an idea how is that possible? Please comment if you do, I'd appreciate it.
To test the deployment process I am trying to deploy the included demo app Minehunt. I am able to get it to run, no crashing or errors, but the screen is all white.
I believe this generally means that I am missing plugins. Dependency walker reports no problems, and I even tried including ALL the plugins from the Qt MingW plugins directory, but no such luck.
Here is what I am including so far; Can anyone advise what else I need to add to get it to run?
Your dlls don't look bad at all. I think, too, that it's your plugins. Even if they are there, there is a good chance, that your program don't find them. Qt is a bit picky where to look by default. You might try qt.conf. This is a small textfile you must create in the folder where your executable lies. It contains the path to your Qt plugins.
For instance, in one of my projects I have the followin folder layout:
Appfolder
plugin
qt
plugins
imageformats
sqldrivers
myapp.exe
qt.conf
...many dlls...
Then I added a qt.conf file to the Appfolder, which has the following content:
[Paths]
Plugins = plugins/qt/plugins
My program is Qt 4, but I don't think this aspect of plugin deployment changed in Qt5.
All my qt dlls are in qt. And I add the following PATH: SET PATH=.\plugins;.\plugins\qt;%PATH%. Works like a charm on any Windows I ever tried.
Edit:
I then created a .bat file, which does:
SET PATH=.\plugins;.\plugins\qt;%PATH%
cd Appfolder
start myapp
This was an ugly quick fix, which I did not have the time to replace with something better, yet.
If application runs and shows blank screen then that usually indicates two things :
All the dependencies (dlls) are probably present and detected properly.
Most probably whats missing is the presence of qml files at the correct location.
In your main.cpp check the path of qml file which you would have given, and see if relatively that folder is present at the same location corresponding to your executable.
Also, instead of running the executable by double clicking, run it through the command line. It might print some messages if it is not able to locate some images/files/other dependencies etc according to the specified paths.
Edit 1 :
Add this flag in the .pro file :
CONFIG += console
It will give the exact debug message in a console once you run the application.
I'm trying to access a MySql database from a Qt application but I get the following error:
QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QSQLITE2
I find this very strange cause I have libqsqlmysql.so on my Qt folder. I have even tried to compile the MySql driver as a static plugin and add it to my .pro file as:
QTPLUGIN += qsqlmysql
But this also generates the same runtime error (it must've found the plugin cause there's no error compiling the application)
What am I missing? I would like to avoid having to compile Qt from source cause this will have to work seamlessly on the deploy machines as well.
BTW: Even though I'm developing and testing on Linux I will need to support Windows. Will I experience this same issue on Windows? How can I compile and link the MySql driver in both Linux and Windows?
The solution:
After following #Sergey's recommendations I did an strace of the application redirecting the output to grep so I could search for 'mysql' and for my surprise the application wasn't looking for the plugin at QTDIR/plugins/sqldrivers where I had libqsqlmysql.so, it was looking at QTDIR/lib. After copying the plugin to the lib folder the MySql connection worked.
Try opening the shared library with dlopen() and see if it loads and if not, what dlerror() tells you. I always run into similar problems on Windows. LoadLibrary()/GetLastError() saved me numerous times (last time it was because of a wrong version of some libiconv/libintl DLL). Running ldd on the plugin may also help.
If dlopen() works fine, try to load the plugin with QPluginLoader. If it doesn't load, then check the buildkey of the plugin. I usually do it the dirty way by running strings on the plugin and then looking for strings like "buildkey" or "QT_PLUGIN_VERIFICATION_DATA". Just looking at the build key and around it may give you an idea. For example, you may realize that you have compiled your plugin in the release mode while your application is compiled in the debug mode. In such case the build key won't match and the plugin won't load. Everything in the build key must match your configuration. Note that the version and the build key are checked differently: the build key must match exactly (or match some black magic called QT_BUILD_KEY_COMPAT), but in the version only the major version must match exactly, the minor version must be the version of Qt the plugin was compiled with or later and the patch level is ignored. So if your plugin was compiled with Qt 4.x.y then it will work with Qt versions 4.z.* where z>=x. This actually makes sense.
If the build key looks okay (which is unlikely if you got to this point), you may wish to look at QLibraryPrivate::isPlugin() source code to figure out what's wrong, but that doesn't look like an easy task to me (although running this in a debugger may help).
If QPluginLoader does load the plugin, check if it is in the right directory and has correct permissions. If you still didn't solve the problem by this point, it's time to look at the SQL module source code that actually loads these plugins. But it is extremely unlikely. I ran into this problem many, many times and it was always either the library not loading or the build key not matching.
Another way to go after QPluginLoader loads the plugin successfully is to use strace to figure out whether the program at least tries to open the plugin file. Searching for something like "sqldrivers" or "plugins" in the strace output should also give away the directory where Qt is searching for its plugins and specifically SQL drivers.
Update
Is it possible to compile the driver as a static plugin and don't worry about anything? Let's try:
d:\Qt4\src\plugins\sqldrivers\psql>qmake CONFIG+=static LIBS+=-Ld:/programs/Post
greSQL/lib INCLUDEPATH+=d:/programs/PostgreSQL/include
d:\Qt4\src\plugins\sqldrivers\psql>make
It compiles fine and now I got libqsqlpsql.a (release) and libqsqlpsqld.a (debug) in QTDIR/plugins/sqldrivers (it is the right place on Windows). I am using PostgreSQL driver here, but I don't think it will be any different for MySQL which I just don't have installed. Ok, let's compile some real program with it:
d:\alqualos\pr\archserv>qmake QTPLUGIN+=qsqlpsql PREFIX=d:/alqualos LIBS+=-Ld:/g
nu/lib INCLUDEPATH+=d:/gnu/include LIBS+=-Ld:/programs/PostgreSQL/lib LIBS+=-lpq
Note that I had to manually link to libpq, otherwise the linker would complain about undefined references. The funny thing is, qmake knows that qsqlpsql is located in QTDIR/plugins/sqldrivers and sets compiler and linker options accordingly. So it still needs to be in the right place to work, only you don't have to worry about your users running into the same problem as it is only used during compilation. An alternative would be to just use LIBS+=-Lpath/to/plugin LIBS+=-lqsqlpsql instead of QTPLUGIN+=qsqlpsql, at least the docs say that it should work, but I haven't tested it.
In order for the application to actually use the plugin I had to put the following in my main unit (CPP file):
#include <QtPlugin>
Q_IMPORT_PLUGIN(qsqlpsql)
It works! Also, from what I've been able to figure out from the sources, the build key and the version are checked only when a plugin is dynamically loaded (all the relevant stuff is in the QLibrary's private class, not even QPluginLoader's). So the resulting executable may (or may not, depending on the binary compatibility) work even with different versions and builds of Qt, although using it with older versions may trigger some bugs that were fixed later.
It is also worth noting that the order for loading SQL drivers is this: use the driver statically linked into Qt if available, then look for a driver registered manually with QSqlDatabase::registerSqlDriver(), then look for a driver statically imported into the application (the way described above), and finally try to load a shared plugin. So when you link statically, your users won't be able to use dynamically linked drivers they may already have, but will be able to use drivers linked statically into Qt (like in Ubuntu).
I compiled QT first and then realised that I need mysql as well. So I compiled mysql plugin by
executing following command in QT-DIR\src\plugins\sqldrivers\mysql folder.
Mysql plugin compile command
qmake "INCLUDEPATH+=$$quote(C:\Program Files\MySQL\MySQL Server 5.5\include)" "LIBS+=$$quote(C:\Program Files\MySQL\MySQL Server 5.5\lib\libmysql.lib)" mysql.pro
Plugings are then created in created in folder QT-DIR\plugins\sqldrivers.
However, when I tried to use it in my code. It failed with following error.
Error msg
QSqlDatabase: QMYSQLDriver driver not loaded
Solution
After some googling and checking Path variable I realised that the Mysql server lib
( C:\Program Files\MySQL\MySQL Server 5.5\lib) directory was not in my Path variable. I expect that the dll in this folder are used by the plugin at runtime. After including Mysql server lib in Path variable everything worked smoothly. Hope this information saves some hair on other programmers scalp, as I uprooted quite a few. :D
Last time I looked at this you needed to rebuild Qt from source and include the appropriate MySQL source.
Building Qt from the sources is not hard, it just takes a while. You are likely to have the required tools already.
A possible workaround may be to access the back-end over ODBC instead.
In order for your app to pick up the plugin at runtime, the shared library implementing the MySQL plugin needs to be placed in the correct directory. The best way of determining that directory is to check the output of QCoreApplication::libraryPaths. You can also force specific paths by using a qt.conf file.
Please note that plugins must be placed in subdirectories within the plugin path, and the final part of the path name (i.e., the parent directory of the shared libraries) cannot be changed. SQL drivers need to go in a directory named sqldrivers, i.e. <pluginpath>/sqldrivers. For more details on plugin directories, see How to Create Qt Plugins.
I was experiencing this same issue as well. I've been installing and experimenting with a lot of different Python tools and UIs. I then uninstalled everything python related. I did a fresh install of Python 3.2, PyQT 3.2, and Eric5. No more errors with the QMySQL driver.
well i have had this issue, and after a lot of time, and different tools, i found that QT ( on windows, have not been able to test on Linux.) loads the "QSQLMYSQL.." when requested, but before runtime the lib ("QSQLMYSQL..") file must reside on one of the searched paths (QApp.libraryPaths()) inside a folder called "sqldrivers".. otherwise QT will just ignore the file, even if it is at some other point inside the searched path.
what i did was to monitor the dependency of a sample app, and when i removed the "QSQLMYSQL.." dll from "plugins\sqldrivers\" it failed, but when i maded a folder inside the app folder, called "sqldrivers" and placed the "QSQLMYSQL..." inside there, it loaded.
what i have is mysql 5.5, qt 4.7.4.
hope anyone can use this, and if anyone knows more about it, i would like to know where to find it(http://doc.qt.nokia.com/stable/sql-driver.html, is the closest you can get to the information about the folder structur). :P
This may also happen if your QMYSQL plugin is linked against the "wrong" mysql_client.a or it isn't in the LD_LIBRARY_PATH. I had this problem on OSX because mysql was installed via ports, and I fixed it with:
install_name_tool -change libmysqlclient.18.dylib /usr/local/mysql/lib/libmysqlclient_r.18.dylib libqsqlmysql.dylib