I am giving Gwan a whirl.
Having made it through example code, I started a small project with more than one source file. I now have two problems:
I got a linking error at server startup:
Linking main.cpp: undefined symbol: _ZN7GwanUrl9concatAllEv
(the main file #includes the two other files; all the files are in the csp directory)
As an alternative to having all the files in the /csp directory, I would like to make a library outside of the /csp directory while still using some of the gwan functions. sadly, a tonne of errors follow -- WHEN I GCC from commandline not via G-WAN Startup.
In file included from /home/ec2-user/gwan/include/gwan.h:22,
from Xbufstream.h:10,
from Xbufstream.cpp:10:
/usr/include/time.h:199: error: ‘size_t’ does not name a type
.....
Anyone knows what the gwan g++ argument string looks like?
(odd the 1. and 1. its 1. and 2. in the editor)
First, this is not a linker issue: you have "undefined symbol" rather than "unresolved symbol" as an error.
This is simply an #include issue.
define the main() function in your script.cpp file.
there's a G-WAN folder dedicated to user-defined include files called /gwan/include but you can as well use /csp/my_include.hpp... if you are using the right syntax:
For example, having #include "toto.hpp" in /csp/hello.cpp lets me reach C++ functions defined and implemented in the gwan/include/toto.hpp file (or defined in toto.hpp and implemented in a pre-compiled library linked to your script with #pragma link).
If you rather use #include <toto.hpp> then the SYSTEM INCLUDE PATH will be searched instead (and this will work providing that your library was correctly installed).
If you want to use #include "toto.hpp" for a custom folder that was not setup in the system, you can use G-WAN's #pragma include "../my_folder" directive to specify its PATH or you can explicitely specify it in each include: #include "../my_folder/toto.hpp".
Nothing fancy there, only C/C++ dependancy rules apply (and G-WAN really helps by providing alternate ways that do not involve system settings).
For libraries (see the G-WAN examples for SQLite, Cairo, mySQL, cURL, etc.) you can either use pre-installed libraries that exported their location in SYSTEM variables... or put your library in the /gwan/libraries folder and their include file in the /gwan/include folder.
When writing your own libraries, remember that they need to be pre-compiled. This means that you obviously cannot use G-WAN symbols since your compiler may #include "gwan.h" (to have the definitions) but your linker will not know from where G-WAN symbols can be found. The way around is to always use the G-WAN API from the G-WAN scripts. Your custom libraries must either be general-purpose or buffer any payload intended to be used by G-WAN. No-double copy is needed since G-WAN provides the set_reply() call to let G-WAN use persistent replies built without the reply xbuffer provided by G-WAN servlets.
Now, a last word about linking (which was not the cause of your trouble but could participate to the confusion). If you mix C and C++, use extern C {} to wrap your C++ prototypes called from C (otherwise you will really have "unresolved symbols").
With all this information, you should be ready to face every possible situation.
the issue of referencing gwan.h symbols inside #include files can also be solved by moving all code into the header file, whether its .h or .hpp
its ungraceful but a fix nevertheless. and good enough for the simple extension i wanted.
looking into the /libraries/sqlite3/sqlite.h helped.
#gil, thanks for your time.
Related
Basically, I get a console window I don't want to see while writing SDL-windowed applications.
In C, the answer is simple: change your linker SubSystem to Windows; then SDL does the rest. It has a macro that redefines your main to SDL_main, which it calls from inside its own hidden WinMain function. Just make sure you take arguments in your main function and all goes smoothly.
In D, I'm having a little more trouble with it. Upon simply changing the subsystem by passing -L/SUBSYSTEM:WINDOWS to the linker, it informs me that I have declared main, SDL has declared WinMain, and it doesn't know how to deal. I thought changing the signature from void main() to extern(C) int SDL_main(int argc, char*[] argv) would solve the problem, but then the linker says it can't locate any of D's runtime symbols. Might have something to do with the entry point being written in C?
On the other side, my problem might be with how I have set up Derelict. I am working from this repository, which is a live-updated amalgam of all the different Derelict repositories on GitHub. In my VisualD solution, I have three relevant projects: a home-brewed Derelict project containing the source to SDL2 and the Utilities library, and the C-API SDL2 and SDL2main projects as found here. I compile and link to all three resulting libraries -- Derelict and SDL2main are static, SDL2 is dynamic. I am less inclined to say this setup is to blame, because it works just fine save the undying console window.
In the command line passed to DMD, add the linker option -L/SUBSYSTEM:WINDOWS
In case you use dub (which i recommend) and gdc, insert the following into your dub.json file:
"dflags": ["-Wl,--subsystem,windows"]
I have a dll file, irig106.dll, that I produced from a compile in Visual Studio 2010. (The source code is here). Notice the multitude of .h files in there; the main one is called irig106ch10.h, as far as I can tell.
I would like to import it into MATLAB via loadlibrary. I put all the .h files into their own folder, called "headers". Here's what I get:
loadlibrary('irig106.dll', 'headers\irig106ch10.h', 'addheader', 'config', 'addheader', 'stdint', 'includepath', '.\headers');
Warning: Warnings messages were produced while parsing. Check the functions you intend to use for correctness. Warning text can be viewed using:
[notfound,warnings]=loadlibrary(...)
Error using loadlibrary (line 418)
There was an error loading the library
"mydir\irig106.dll"
mydir\irig106.dll
is not a valid Win32 application.
So I'm not sure of a few things:
Why is loadlibrary claiming that the dll is not a valid Win32 application? It looks like based on my Visual Studio settings, I am compiling for Win32.
Per the loadlibrary documentation, I need to explicitly use addheader for each header file I want to include, and those headers need to be #included in the base header file. In this case, I only include config.h and stdint.h in irig106ch10.h but I'd like to use all those other headers. Do I need to make a "header header" file where I include everything?
I guess I'm looking for a tutorial on how to use loadlibrary for complicated dlls with multiple headers like this, because there really isn't much in the way of examples on the internet. I'd love to see someone build the .dll (uncomment the #define IRIG_NETWORKING in config.h) and give a step-by-step.
I've run into trouble in the past when I've tried porting some C++ code written on Mac OS X to a Linux system, or trying to compile code written against an older version of gcc/g++ with a newer one:
It seems that some (older?) versions of gcc/g++ would automatically include some header files for you.
For example, code that uses printf should require #include <stdio.h>. And code that uses memcpy should require #include <string.h>. But depending on the version of gcc I'm using, it will occasionally include these for me.
It wreaks havoc when I forget to include something and then never get errors until I go to compile the code on another system. At that point it's a game of running all over the project and fixing the includes.
Has anyone else run into this? Is there a way to force gcc to autoinclude or to not autoinclude? Or, is there a way to know what it's autoincluding?
-include file
Process file as if #include "file" appeared as the first line of the primary source file. However, the first directory searched for file is the preprocessor's working directory instead of the directory containing the main source file. If not found there, it is searched for in the remainder of the #include "..." search chain as normal.
If multiple -include options are given, the files are included in the order they appear on the command line.
http://gcc.gnu.org/onlinedocs/gcc/Preprocessor-Options.html
Are you sure it's not other headers pulling those one's in, and on the other platforms not doing so?
When compiling on different systems, you might meet different problems and not only includes.
I would suggest investing in a continuous build system that will compile on all OS you need after each update of the code, so you are rapidly aware of any portability issue.
You can also put all common system header files inside a specific header file you will write and systematically include it in all your files.
I have a project compiled using __cdecl calling convention (msvc2010) and I compiled boost using the same compiler using the default settings.
The project linked with boost but I at runtime I got an assert message like this:
File: ...\boost\boost\program_options\detail\parsers.hpp
Line: 79
Run-Time Check Failure #0 - The value of ESP was not properly saved across a function call. This is usually a result of calling a function declared with one calling convention with a function pointer declared with a different calling convention.
There are the following questions:
what calling convention does boost build with by default on Windows (msvc2010)
how to I compile boost with __cdecl calling convention
why boost wasn't able to prevent linking with code with different calling conventions? I understood that boost has really smart library auto-inclusion code.
Update #1
It looks that boost does compile and link with proper calling convention, still at runtime I get the above problem. I did a sample application using the same code and it works but in my application it fails. The only difference could be from project configuration or includes/stdafx.h
Just use
bjam ... **cxxflags=/Zp4**
while building boost libraries.
As far as I know there's not way to make C++ use cdecl calling conventions (see MSDN Calling Convention). The C++ method calling is just different from C. The only opportunity that you have to use one of the C calling conventions is for functions, which include class static functions in C++. If you know that's the case you can try forcing the option when building by adding the option during the build:
bjam cxxflags=/Gd ...
(see BBv2 Builtin features)
Or to make it "permanent" set up a user-config.jam with your compiler and add it to the build options for all BBv2 msvc builds (see BBv2 Configuration and related docs). As for you other questions:
Boost uses the default calling convention MSVC uses, except for cases where it overrides it at the code level. I don't know where those are as they are library specific. So you'd have to search the code for the "__*" code decorators.
See above for partial answer.
Detection; there are two reasons: There is a limit to how many different options we can reasonably detect for for building as it's an exponential growth of different possible variations so we limit it to the most important cases. And in the case of calling convention, it's not actually possible since it's something that can be changed on a per function basis.
I found the cause of the problem inside one of the shared property files: <StructMemberAlignment>4Bytes</StructMemberAlignment>
If I remove it the code will work. Still, I'm not sure why this is happening and how could I solve it without removing the above code (that was required by another library).
I added another question regarding boost and structure member alignment.
I'm using Visual Studio .NET 2003, and I'm trying to port code I've written and compiled/run successfully in Linux GCC to Windows.
I'm a newbie when using VS. I've created a new project, and added all the .c and .h files I have into the project by Project -> Add Existing Items, then chose all the .c and .h files.
I'm not familiar with how exactly compilers and linkers etc work, but is there a difference between how VS and gcc compile/link #include files? My habit of programming in Linux has been to have one main.c file, and #include all other .h or .c files that I need. Then I would only compile the main.c file. But in VS, it seems as if the #include files are not "seen" by the program, because I'm getting errors that tell me certain structures or variables were not declared, even though they are in my user-defined header files.
I'm also getting errors like DIR is an undeclared identifier. I've included , so why can't it recognize DIR?
Thank you.
Regards,
Rayne
Consider compiling your program with windows port of gcc (from Mingw32 or Cygwin) first. This will provide you with more familiar environment. If you'll still have to compile everything with VC++, you'll have more incremental process of porting.
Also, it is not evident from your post, but it seems you are trying to use dirent.h. Note that dirent.h (and corresponding libs) is not included with VC++.
One of the best ways to learn would be to start with the smallest application that you can compile on both. Expand this working and portable application step by step into the more fully featured application you desire.
Remember to add all .c/.cpp files to the 'Source Files' directory in the project as they won't be compiled otherwise.
Restrict any non-portable code (that you will need) to a single place. For example if you need to create threads, have a common create thread function used throughout (but implemented differently). Using portable libraries such as Boost can help here.