CSFML D: Missing symbol errors - graphics

Question

I am using the official (dynamic) D bindings to CSFML (https://github.com/BindBC/bindbc-sfml).
As a prerequisite, I installed CSFML 2.5 using the following command (my operating system is Linux):
sudo apt-get install libcsfml-dev
I then imported the dynamic libraries into my project typed in the following code to get started...
Main code:
import std.stdio;
import bindbc.sfml;
import bindbc.loader;
import std.string;
import std.conv;
import loader = bindbc.loader.sharedlib;
void loadDyn() {
if (!loadSFML()) {
string[] messages;
foreach (const(ErrorInfo) err; loader.errors) {
string errorStr = to!string(err.error);
string messageStr = to!string(err.message);
messages ~= format("Error: %s, Message: %s", errorStr, messageStr);
}
throw new Exception(format("Fatal error(s) encountered whilst calling `loadSFML()` function: %s %s %s", messages, loadedSFMLSystemVersion(), loadedSFMLGraphicsVersion()));
}
}
void main() {
loadDyn();
sfContextSettings* settings;
sfRenderWindow* window = sfRenderWindow_create(sfVideoMode(640, 480), "Hi", sfWindowStyle.sfDefaultStyle, settings);
while (window.sfRenderWindow_isOpen()) {
sfEvent event;
while (window.sfRenderWindow_pollEvent(&event)) {
if (event.type == sfEventType.sfEvtClosed) {
window.sfRenderWindow_close();
}
}
window.sfRenderWindow_clear(sfBlack);
window.sfRenderWindow_display();
}
}
dub.json
{
"authors": [
"Tom"
],
"dependencies": {
"bindbc-sfml": "~>1.0.1",
"bindbc-loader": "~>1.0.0"
},
"versions": [
"SFML_Audio",
"SFML_Graphics",
"SFML_250"
],
"description": "A minimal D application.",
"license": "proprietary",
"name": "sfml"
}
Running the program, I get the following errors:
object.Exception#source/app.d(20):
Fatal error(s) encountered whilst calling `loadSFML()` function: [
"Error: Missing Symbol, Message: sfRenderTexture_createWithSettings",
"Error: Missing Symbol, Message: sfRenderTexture_getMaximumAntialiasingLevel",
"Error: Missing Symbol, Message: sfText_getLineSpacing",
"Error: Missing Symbol, Message: sfText_getLineSpacing"
] sfml250 sfml240
----------------
source/app.d:20 void app.loadDyn() [0x55d6ef8b19c2]
source/app.d:25 _Dmain [0x55d6ef8b19e4]
Program exited with code 1
I asked for help about this issue online, and the owner of the library told me to check my SFML system and SFML graphics versions by calling the loadedSFMLSystemVersion() and loadedSFMLGraphicsVersion() functions.
The loadedSFMLSystemVersion() function returned 2.5.0 whilst the loadedSFMLGraphicsVersion() returned 2.4.0. There is a version conflict.
The owner of the bindings had this to say about the problem:
Usually, a failure to load the configured version is because a lower version of the C library is installed (as in, you've asked for 2.5, but only have 2.4 installed). But that's not always the case. It could also be because there's a bug in the binding, or because the shared library was compiled without support for specific functions, or maybe the shared library has somehow become corrupt.
So, back to your specific case. Though it's possible that a CSFML apt package would bundle one version of the CSFML graphics library and another version of everything else, it seems rather unlikely. CSFML 2.5 means 2.5 of everything. And looking at the official apt repository lists, they show the package has 2.5 of everything. You could verify this by looking for the shared libraries on your system, but there's no need. I'm sure you have 2.5 installed.
Furthermore:
My first thought at this stage would be to look for a bug in the binding. Perhaps the function names are misspelled. But that's not the case. Everything is spelled correctly.
So my next thought would be to check the shared library. Maybe the build was misconfigured so that the missing functions weren't properly exported.
The owner of the library is suggesting that the version conflict is due to an internal issue/bug, which I am unable to properly find as it's out of my scope.
For some reason, downgrading to version 2.4 fixes this issue, but I would like to use version 2.5 which I am unable to due to these errors.

Answer 1

Looking at the code that sets the system version
It looks like the value returned by loadedSFMLSystemVersion will always be whatever you have defined for the version (it just sets the value to the enum defined in config.d), regardless of the support of the library.
So I don't think this mismatch is indicative of the error. What seems to be happening is that the code that loads the graphics binding isn't finding one or more of the functions that it requires to declare that 2.5 is supported.
See the list of functions here, at least one of these isn't loading.
Looking at your first error message, it's the first function in the list. Indeed, I'd say it really does appear that the library is not the 2.5 version, but the 2.4 version.
I am not familiar with this library, but the first thing I would check is whether you have the right .so file. To do this try:
dpkg -L libcsfml-dev
This might tell you what library version you have installed.
If you do think this is the right version, try using nm on the .so file, and see if you can find that symbol defined there. If not, then the built library just doesn't include that function. Perhaps that's because the function name is incorrect in the bindbc binding, and perhaps it's as the author says -- the library wasn't built with that function.