Fix: https://github.com/Exiv2/exiv2/issues/521

conversions.sh reveals a (harmless) order change runTest exiv2 -M'set Xmp.xmp.ModifyDate 2015-04-17T18:10:22Z' v.xmp

include/exiv2/xmp_exiv2.hpp

@@ -209,13 +209,9 @@ namespace Exiv2 {
          */
         int add(const Xmpdatum& xmpdatum);
         /*!
-          @brief Delete the Xmpdatum at iterator position pos, return the
-                 position of the next Xmpdatum.
-
-          @note  Iterators into the metadata, including pos, are potentially
-                 invalidated by this call.
+          @brief Delete the Xmpdatum at iterator position pos and update pos
          */
-        iterator erase(iterator pos);
+        void erase(iterator& pos);
         //! Delete all Xmpdatum instances resulting in an empty container.
         void clear();
         //! Sort metadata by key

src/xmp.cpp

@@ -382,10 +382,20 @@ namespace Exiv2 {
         return xmpMetadata_.end();
     }
 
-    XmpData::iterator XmpData::erase(XmpData::iterator pos)
-    {
-        return xmpMetadata_.erase(pos);
+    void XmpData::erase(XmpData::iterator& pos)
+    {
+        // https://github.com/Exiv2/exiv2/issues/521
+        // delete 'children' of XMP composites (XmpSeq and XmpBag)
+        std::string key = pos->key();
+        while ( pos != end() ) {
+            if ( pos->key().find(key)==0 ) {
+                xmpMetadata_.erase(pos);
+            } else {
+                break ;
+            }
         }
+    }
+
 
     bool XmpParser::initialized_ = false;
     XmpParser::XmpLockFct XmpParser::xmpLockFct_ = 0;

test/data/conversions.out

@@ -149,18 +149,18 @@ Iptc.Envelope.CharacterSet                   String      3  %G
 
 Testcase 15
 ===========
+Xmp.xmp.ModifyDate                           XmpText    20  2015-04-17T18:10:22Z
 Xmp.exif.ExifVersion                         XmpText     4  2.21
 Xmp.exif.GPSVersionID                        XmpText     7  2.2.0.1
 Xmp.exif.GPSLatitude                         XmpText    12  3,8.4955752N
 Xmp.exif.GPSTimeStamp                        XmpText    29  2003-12-14T01:02:00.999999999
+Xmp.exif.ComponentsConfiguration             XmpSeq      4  YCbCr
 Xmp.exif.Flash                               XmpText     0  type="Struct"
 Xmp.exif.Flash/exif:Fired                    XmpText     4  True
 Xmp.exif.Flash/exif:Return                   XmpText     1  0
 Xmp.exif.Flash/exif:Mode                     XmpText     1  1
 Xmp.exif.Flash/exif:Function                 XmpText     5  False
 Xmp.exif.Flash/exif:RedEyeMode               XmpText     4  True
-Xmp.exif.ComponentsConfiguration             XmpSeq      4  YCbCr
-Xmp.xmp.ModifyDate                           XmpText    20  2015-04-17T18:10:22Z
 Xmp.photoshop.DateCreated                    XmpText    29  2003-12-14T12:01:44.999999999
 Exif.Image.DateTime                          Ascii      20  2015:04:18 02:10:22
 Exif.Image.ExifTag                           Long        1  70