I'm trying to build the Poco C++ libraries manually on Android, iOS, and windows. After much effort I got them to build on Android, but I'm struggling a bit on Windows.
I've had to manually edit several files already to resolve undefined symbols -- specifically File & Path weren't #included properly by *_WIN32U.cpp versions.
I'm down to what APPEARS to be my last compiler issue for "Foundation". It's this line in Process_WIN32U.cpp:
envChars = getEnvironmentVariablesBuffer(env);
The compiler error generated is:
"getEnvironmentVariablesBuffer identifier not found"
The declaration of "getEnvironmentVariablesBuffer" is in Process.cpp but it's not a member of the root class, there are no EXTERN references anywhere, and no header file contains the function declaration.
So how the heck is "Process_WIN32U.cpp" supposed to be able to see that function?
Thanks!
So how the heck is "Process_WIN32U.cpp" supposed to be able to see that function?
ProcessWIN32U.cpp (i.e. ProcessImpl class) is able to see that function because ProcessWIN32U.cpp is included from Process.cpp and it was not designed or meant to be used standalone - it is excluded from build in POCO Visual Studio solutions.
In order to get ProcessWIN32U.cpp to be included by Process.cpp, one must manually /D_WIN32 which is not defined by Visual Studio (it defines WIN32).
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I am trying to write a plugin for a popular program whose code and compilation process I do not have control over. The program is written in C. However, I have written parts of my plugin in C++, since I use the QT5 library for graphics capabilities. The functions that the C program calls are written in C.
When the C program tries to load the plugin (shared library), it produces this error:
dlopen('build/libfoo.so') failed: build/libfoo.so: undefined symbol: _ZTV13JoystickPanel
JoystickPanel is a class in the C++ part of the program.
I've tried rewriting parts of the program in C, but the error was unaffected. I know that I could rewrite the entire program in C, but I'd rather not have to switch to another, more C-friendly GUI framework. I've also opened up libfoo.so in a text editor and search for JoystickPanel, but it appears to be mangled as _ZN13JoystickPanel.
Are there any compiler options or solutions that I'm missing?
I have no idea what _ZN13JoystickPanel means, since it's not apparently a valid mangled C++ name. It should perhaps be _ZN13JoystickPanelE, which would translate to JoystickPanel. That'd be symbol name for sure, but without much meaning anyway. You must have truncated something: I tried quite a bit and just can't generate an object file that would include _ZN13JoystickPanel as the complete symbol. It's just a prefix, there should be a "second half" attached to it - was there?
But _ZTV13JoystickPanel is the vtable for the JoystickPanel class. It's missing because you didn't provide implementations for all the virtual methods of the JoystickPanel class. Most likely, you didn't invoke moc properly, or forgot to compile and link its output.
You need to show a complete build script for your plugin at the very least (the .pro file, or CMakeLists.txt). You'll also need to provide a github link to your project (I presume it's open source).
The symbols you want to find in the compiled output are at least _ZTV13JoystickPanelD#Ev - virtual destructors, where # is a digit, _ZTV13JoystickPanel - the virtual method table,
Those symbols may be absent when compiled with optimization and/or LTCG, but also absent will be references to them.
You may wish to delete the build folder and rebuild your project, just to be sure. qmake is bad at dependency generation for the makefiles it produces, so if you use it, I suggest switching to cmake + ninja.
Apparently, I'd forgetten to put the #include "moc_controller.cpp" line at the bottom of a file that needed it.
For anyone else chasing this issue while using Qt on CMake, consider making sure that the proper lines are added.
I am a newbie in C/C++, just in case :)
I have cloned an older protocol stack solution written in C with one main class in C++ imported it into VS
(Visual C++ 2017 v 15.9.5 targeting Windows SDK 10.0.17134.0) it compiled correctly and working.
Now made a C++ solution (windows console application) created a folder lib copy pasted all those .h and .c files into lib added the path to additional include directories and also in linker additional library directories.
Building the Solution throwing tones of errors. the one I am trying to fix now is:
One of the header files contains type definitions
typedef uint8_t U8;
#ifndef BOOL
typedef U8 BOOL;
#endif
but this is conflicting with minwindef.h from windows kit. though I #include types.h getting C2371 'BOOL': redefinition; different basic types
in the whole solution, I want to use this definition of BOOL and all other ones defined in this header.
How should I solve the issue? Or in General in case of using C codes in C++ projects what settings and MACRO (e.g. extern "C" in methods) should I follow
I don't know anything about the library you're trying to work with, because you did not tell us what it is. But I can make some guesses:
The code did not used to interface with Windows code at all;
By creating a Windows C++ application you have added Windows dependencies;
The Windows dependencies (well-known for poisoning the namespace with short names like BOOL) are conflicting with the library's code (which is doing the same thing with its BOOL macro, when defined, and its BOOL type alias, otherwise).
This isn't really to do with C vs C++ or anything like this, and there's no general fix you can make. You can either try to get rid of the Windows dependency (do you need that header for your task?) or you can patch your library not to touch BOOL (after making sure that Windows's BOOL is what you need it to be).
And use this as a good lesson not to pollute namespaces!
I'm trying to have Cmake check if the file cxxabi.h is available. This file is from the c++ standard library, at least with g++. My current cmake commands look like this:
include(CheckIncludeFiles)
...
check_include_files(cxxabi.h HAVE_CXXABI)
if(HAVE_CXXABI)
...
else(HAVE_CXXABI)
...
endif(HAVE_CXXABI)
When this is executed, I get:
-- Looking for include files HAVE_CXXABI
-- Looking for include files HAVE_CXXABI - not found.
Although the file is available in /usr/include/c++/4.6.4/ and can properly be found by g++ when I compile a c++ code.
I suspect the macro check_include_files uses the C compiler instead of the C++ one to compile a small program that includes the required file, which of course fails since cxxabi.h is a C++ file.
Any idea how to solve that? (i.e. making the macro use the C++ compiler instead of the C one)
As edited in my original question:
Problem solved. There is a different macro for C++ headers, check_include_file_cxx, located in CheckIncludeFileCXX.
There exists another problem with CHECK_INCLUDE_FILES that I recently discovered with MinGW. The file tested was "ddk/ntapi.h". In the CMakeErr.log for this header I got a multiply messages like "DWORD - does not name a type" and so on for all MS types used in this header. Because of this reason the compilation fails and a requested header appears as "not found", whereas it is not true.
This happens because CheckIncludeFile.cxx contains only the requested header, and some headers in MinGW (and probably in the other APIs) does not include in its body all the list of required headers to be compiled in a standalone program that CMake creates.
The solution for this problem is to add absent basic includes into the CMAKE_REQURED_FLAGS, or as a third variable of CHECK_INCLUDE_FILE_CXX:
CHECK_INCLUDE_FILE_CXX("ddk/ntapi.h" VAR "-include windows.h")
can someone please help me to understand the process.
in c++ visual studio 2010
i have a visual studio solution (lets call it mysol)
i have a project built as a static library (let's call it staticprj)
staticprj needs to use a library from outside (lets call it ext.lib)
in the body of the source code of staticprj i include outside library header file with
# include extlib.h and make calls to some of its functions (let call them extfunctions())
i also include the the path to the header files location of the ext.lib.
the staticprj compiles okay without errors
the mysol also has another project which is a dynamic library (dynprj) and which depends on the staticprj.
also in the source files of the dynprj uses functions from outside library.
i have included #include extlib.h in the source code of dynprj.
i have included the path of the header files
i have attached extlib.h directly to the dynprj
i have also added ext.lib to the linker input (along with the path where the ext.lib resides).
i still get a lnk2001 error stating that extfunctions() where not found.
the whole structure (the mysol solution) compiles okay if i do not use ext.lib at all.
my question is how does the linking process works and what can i do to correct this linking error.
(note that without the presence of ext.lib my linking of the staticprj and dynprj is fine. my compilation works okay and my code works. i only get the linking error when i try to link another ext.lib to staticprj and dynprj and use functions from ext.lib)
thanks in advance.
I'm not quite sure it will work, but try putting the .dll inside your "mysol" debug folder. I had a similar problem couple of weeks ago when I had library compiled as .dll. I just placed that .dll within my debug folder and worked lovely.
I am trying to compile a Visual Studio / C++ code snippet I have found on the internet containing the function:
Marshal::SizeOf()
When compiling the snippet, I get the error message:
error C2653: 'Marshal' : is not a class or namespace name
so I think I need to include a header file with the definition of this namespace or class, and the SizeOf() function.
When I look up Marshal::SizeOf C++ in Google I find this help page, however on this page there is no information regarding which header file must be included in order to use this function.
Is there a documentation page where one can look up all .NET classes and functions and easily find the C++ header file that must be included in order to use them?
You need to understand what C++/CLI is. It is a proprietary extension to C++ by Microsoft to make the interfacing between native and managed code (i.e. .Net) easy.
Marshal is not a C++ class, it's a C++/CLI class. As such, there's no header to include. It's #import you are looking for.