Fix for https://github.com/Exiv2/exiv2/issues/560 (eraseFamily() crashes in MSVC/Debug).

include/exiv2/xmp_exiv2.hpp

@@ -219,10 +219,10 @@ namespace Exiv2 {
         iterator erase(XmpData::iterator pos);
         /*!
           @brief Delete the Xmpdatum at iterator position pos and update pos
-                 eraseFamily erases data from the same family
+                 erases all following keys from the same family
                  See: https://github.com/Exiv2/exiv2/issues/521
          */
-        void eraseFamily(iterator &pos);
+        void eraseFamily(XmpData::iterator& pos);
         //! Delete all Xmpdatum instances resulting in an empty container.
         void clear();
         //! Sort metadata by key

src/actions.cpp

@@ -1615,7 +1615,7 @@ namespace Action {
         if (modifyCmd.metadataId_ == xmp) {
             Exiv2::XmpData::iterator pos;
             Exiv2::XmpKey xmpKey = Exiv2::XmpKey(modifyCmd.key_);
-            while((pos = xmpData.findKey(xmpKey)) != xmpData.end()) {
+            if((pos = xmpData.findKey(xmpKey)) != xmpData.end()) {
                 xmpData.eraseFamily(pos);
             }
         }

src/xmp.cpp

@@ -390,14 +390,26 @@ namespace Exiv2 {
     {
         // https://github.com/Exiv2/exiv2/issues/521
         // delete 'children' of XMP composites (XmpSeq and XmpBag)
-        std::string key = pos->key();
-        while ( pos != end() ) {
+
+        // I build a StringVector of keys to remove
+        // Then I remove them with erase(....)
+        // erase() has nasty side effects on its argument
+        // The side effects are avoided by the two-step approach
+        // https://github.com/Exiv2/exiv2/issues/560
+        std::string         key(pos->key());
+        Exiv2::StringVector keys;
+        while ( pos != xmpMetadata_.end() ) {
             if ( pos->key().find(key)==0 ) {
-                erase(pos);
+                keys.push_back(pos->key());
+                pos++;
             } else {
                 break;
             }
         }
+        // now erase the family!
+        for ( Exiv2::StringVector_i it = keys.begin() ; it != keys.end() ; it++ ) {
+            erase(findKey(Exiv2::XmpKey(*it)));
+        }
     }