diff -ur doxygen-1.9.2.orig/src/dirdef.cpp doxygen-1.9.2/src/dirdef.cpp

--- doxygen-1.9.2.orig/src/dirdef.cpp	2021-08-17 19:10:43.000000000 +0200

+++ doxygen-1.9.2/src/dirdef.cpp	2021-09-12 21:25:51.878853938 +0200

@@ -47,7 +47,7 @@

     virtual bool isLinkableInProject() const;

     virtual bool isLinkable() const;

     virtual QCString displayName(bool=TRUE) const { return m_dispName; }

-    virtual const QCString &shortName() const { return m_shortName; }

+    virtual const QCString shortName() const { return m_shortName; }

     virtual void addSubDir(DirDef *subdir);

     virtual const FileList &getFiles() const { return m_fileList; }

     virtual void addFile(const FileDef *fd);

@@ -66,6 +66,7 @@

     virtual void setDiskName(const QCString &name) { m_diskName = name; }

     virtual void sort();

     virtual void setParent(DirDef *parent);

+    virtual void setDirCount(int count);

     virtual void setLevel();

     virtual void addUsesDependency(const DirDef *usedDir,const FileDef *srcFd,

                                    const FileDef *dstFd,bool inherited);

@@ -92,7 +93,7 @@

     QCString m_shortName;

     QCString m_diskName;

     FileList m_fileList;                 // list of files in the group

-    int m_dirCount;

+    int m_dirCount = -1;

     int m_level;

     DirDef *m_parent;

     UsedDirLinkedMap m_usedDirs;

@@ -107,8 +108,6 @@

 //----------------------------------------------------------------------

 // method implementation

-static int g_dirCount=0;

-

 DirDefImpl::DirDefImpl(const QCString &path) : DefinitionMixin(path,1,1,path)

 {

   bool fullPathNames = Config_getBool(FULL_PATH_NAMES);

@@ -132,7 +131,6 @@

     m_dispName = m_dispName.left(m_dispName.length()-1);

   }

-  m_dirCount   = g_dirCount++;

   m_level=-1;

   m_parent=0;

 }

@@ -163,6 +161,11 @@

    m_parent=p;

 }

+void DirDefImpl::setDirCount(int count)

+{

+  m_dirCount=count;

+}

+

 void DirDefImpl::addFile(const FileDef *fd)

 {

   m_fileList.push_back(fd);

@@ -993,7 +996,6 @@

   {

     for (const auto &fd : *fn)

     {

-      //printf("buildDirectories %s\n",qPrint(fd->name()));

       if (fd->getReference().isEmpty())

       {

         DirDef *dir;

@@ -1038,7 +1040,24 @@

   std::sort(Doxygen::dirLinkedMap->begin(),

             Doxygen::dirLinkedMap->end(),

             [](const auto &d1,const auto &d2)

-            { return qstricmp(d1->shortName(),d2->shortName()) < 0; });

+            {

+              QCString s1 = d1->shortName(), s2 = d2->shortName();

+              int i = qstricmp(s1,s2);

+              if (i==0) // if sort name are equal, sort on full path

+              {

+                QCString n1 = d1->name(), n2 = d2->name();

+                int n = qstricmp(n1,n2);

+                return n < 0;

+              }

+              return i < 0;

+            });

+

+  // set the directory count identifier

+  int dirCount=0;

+  for (const auto &dir : *Doxygen::dirLinkedMap)

+  {

+    dir->setDirCount(dirCount++);

+  }

   computeCommonDirPrefix();

 }

diff -ur doxygen-1.9.2.orig/src/dirdef.h doxygen-1.9.2/src/dirdef.h

--- doxygen-1.9.2.orig/src/dirdef.h	2021-05-12 20:51:20.000000000 +0200

+++ doxygen-1.9.2/src/dirdef.h	2021-09-12 21:25:42.394830066 +0200

@@ -95,7 +95,7 @@

     virtual bool isLinkableInProject() const = 0;

     virtual bool isLinkable() const = 0;

     virtual QCString displayName(bool=TRUE) const = 0;

-    virtual const QCString &shortName() const = 0;

+    virtual const QCString shortName() const = 0;

     virtual void addSubDir(DirDef *subdir) = 0;

     virtual const FileList &getFiles() const = 0;

     virtual void addFile(const FileDef *fd) = 0;

@@ -115,6 +115,7 @@

     virtual void writeTagFile(TextStream &t) = 0;

     virtual void setDiskName(const QCString &name) = 0;

+    virtual void setDirCount(int count) = 0;

     virtual void sort() = 0;

     virtual void setParent(DirDef *parent) = 0;

     virtual void setLevel() = 0;