Change GDExtension's library_path back to an absolute path

[dsnopek]

In Godot 4.1, the library path is an absolute path to the library.

After PR #82603, it's no longer guaranteed to be absolute, but matches whatever path was given in the .gdextension file, which could be a res:// style path.

This PR should change it back to it being an absolute path.

Marking as a draft, so that the folks experiencing this problem can test and let me know if it fixes the issue for them!

[fuzzybinary]

Tested and this fixes my issue.

[maiself]

This seems to fix things when running the editor, but an exported project now receives an invalid path. open_dynamic_library() has a fourth argument that returns the true path to the library, but is unused after #82603. I think that needs to be reincorporated somehow to fix this properly.

[maiself]

diff of my attempt

diff --git a/core/extension/gdextension.cpp b/core/extension/gdextension.cpp
index 6c3d0a6148..908a7e8547 100644
--- a/core/extension/gdextension.cpp
+++ b/core/extension/gdextension.cpp
@@ -678,15 +678,16 @@ GDExtensionInterfaceFunctionPtr GDExtension::get_interface_function(StringName p
 }
 
 Error GDExtension::open_library(const String &p_path, const String &p_entry_symbol) {
-	library_path = p_path;
-
 	String abs_path = ProjectSettings::get_singleton()->globalize_path(p_path);
+
+	bool library_path_set = false;
+
 #if defined(WINDOWS_ENABLED) && defined(TOOLS_ENABLED)
 	// If running on the editor on Windows, we copy the library and open the copy.
 	// This is so the original file isn't locked and can be updated by a compiler.
 	if (Engine::get_singleton()->is_editor_hint()) {
 		if (!FileAccess::exists(abs_path)) {
-			ERR_PRINT("GDExtension library not found: " + library_path);
+			ERR_PRINT("GDExtension library not found: " + abs_path);
 			return ERR_FILE_NOT_FOUND;
 		}
 
@@ -701,7 +702,7 @@ Error GDExtension::open_library(const String &p_path, const String &p_entry_symb
 
 		Error copy_err = DirAccess::copy_absolute(abs_path, copy_path);
 		if (copy_err) {
-			ERR_PRINT("Error copying GDExtension library: " + library_path);
+			ERR_PRINT("Error copying GDExtension library: " + abs_path);
 			return ERR_CANT_CREATE;
 		}
 		FileAccess::set_hidden_attribute(copy_path, true);
@@ -709,12 +710,16 @@ Error GDExtension::open_library(const String &p_path, const String &p_entry_symb
 		// Save the copied path so it can be deleted later.
 		temp_lib_path = copy_path;
 
+		// Save the original path of the library.
+		library_path = abs_path;
+		library_path_set = true;
+
 		// Use the copy to open the library.
 		abs_path = copy_path;
 	}
 #endif
 
-	Error err = OS::get_singleton()->open_dynamic_library(abs_path, library, true);
+	Error err = OS::get_singleton()->open_dynamic_library(abs_path, library, true, library_path_set ? nullptr : &library_path);
 	if (err != OK) {
 		ERR_PRINT("GDExtension dynamic library not found: " + abs_path);
 		return err;

Caveat here is during editor runs on Windows library_path will point to the original library instead of the loaded copy. Not sure if that's actually an issue.

[dsnopek]

open_dynamic_library() has a fourth argument that returns the true path to the library, but is unused after #82603. I think that needs to be reincorporated somehow to fix this properly.

Ah, thanks, I didn't notice the change with regard to the 4th argument.

I haven't had a chance to test it yet, but my latest push attempts to incorporate that.

[maiself]

I haven't actually tested it, but the latest version looks good!

[dsnopek]

Alright, I finally got around to testing this! On Windows, it's now giving me the expected library path AND I've confirmed that this doesn't regress the fix from PR #82603. This one should be ready now!

[akien-mga]

Looks good to me.

[akien-mga]

Thanks!