Fix ReosurcesMergingHelper wrongly modifing extensions of files having filename conflicts during export

Core/GDCore/IDE/Project/ResourcesMergingHelper.cpp

@@ -49,11 +49,25 @@ void ResourcesMergingHelper::SetNewFilename(gd::String oldFilename,
                                             gd::String newFilename) {
   if (oldFilenames.find(oldFilename) != oldFilenames.end()) return;
 
-  // Make sure that the new filename is not already used.
-  gd::String finalFilename = gd::NewNameGenerator::Generate(
-      newFilename, [this](const gd::String& name) {
-        return newFilenames.find(name) != newFilenames.end();
-      });
+  // Extract baseName and extension from the new filename
+  size_t extensionPos = newFilename.find_last_of(".");
+  gd::String extension =
+      extensionPos != gd::String::npos
+          ? newFilename.substr(extensionPos, newFilename.length())
+          : "";
+  gd::String baseName = newFilename.substr(0, extensionPos);
+
+  // Make sure that the new filename is not already used. Generate a
+  // new filename while there is a collision.
+  // Preserving extension is important.
+  gd::String finalFilename =
+      gd::NewNameGenerator::Generate(
+          baseName,
+          [this, extension](const gd::String& newBaseName) {
+            return newFilenames.find(newBaseName + extension) !=
+                   newFilenames.end();
+          }) +
+      extension;
 
   oldFilenames[oldFilename] = finalFilename;
   newFilenames[finalFilename] = oldFilename;

Core/GDCore/IDE/Project/ResourcesMergingHelper.h

@@ -18,8 +18,10 @@ class AbstractFileSystem;
 namespace gd {
 
 /**
- * \brief ResourcesMergingHelper is used (mainly during compilation) so
- * as to inventory resources and change their filenames
+ * \brief ResourcesMergingHelper is used (mainly during export)
+ * to list resources and generate new filenames, to allow them to be all copied
+ * in a single directory (potentially changing the filename to avoid conflicts,
+ * but preserving extensions).
  *
  * \see ArbitraryResourceWorker
  *
@@ -82,9 +84,9 @@ class GD_CORE_API ResourcesMergingHelper : public ArbitraryResourceWorker {
                                       ///< baseDirectory, will be preserved in
                                       ///< filenames.
   bool preserveAbsoluteFilenames;  ///< If set to true, the filenames which are
-                                   ///< absolute ( C:\MyFile.png ) will not be
-                                   ///< transformed into their filenames (
-                                   ///< MyFile.png ).
+                                   ///< absolute (C:\MyFile.png  will not be
+                                   ///< transformed into a relative filename
+                                   ///< (MyFile.png).
   gd::AbstractFileSystem&
       fs;  ///< The gd::AbstractFileSystem used to manipulate files.
 };