Reading CSV files with blank columns using VRT

[jduckles]

This is minor, but has had me scratching my head for a few minutes on two occasions. If you create a vrt for a .csv file which has trailing empty columns, the VRT driver fails ungracefully. I received data from a client exported from a spreadsheet which had empty columns (the extraneous commas at the end of each line) like:

lat,lon,wypt,,
44.0000,-88.0000,,
42.0000,-87.0000,,

Created a VRT file to use with ogr2ogr

<OGRVRTDataSource>
  <OGRVRTLayer name="test">
    <SrcDataSource>test.csv</SrcDataSource>
    <GeometryType>wkbPoint</GeometryType>
    <LayerSRS>WGS84</LayerSRS>
    <GeometryField encoding="PointFromColumns" x="lon" y="lat"/>
  </OGRVRTLayer>  
</OGRVRTDataSource>

Running a:

ogrinfo test.vrt

Gives:

ERROR 4: Update access not supported for VRT datasources.
ERROR 1: Unable to identify source X or Y field for PointFromColumns encoding.
FAILURE:

Removing the extra commas fixes the problem as a workaround, but it would be nice for OGR to gracefully handle this common situation.

[Even Rouault]

Fixed in trunk in r15197