[QGIS-Developer] QGIS3: reminder of an annoying bug

[Tobias Wendorff]

Dear developers!

Just before the upcoming freeze and the release of QGIS3, I would like
to remind you of a bug: https://github.com/OSGeo/proj.4/issues/571

Summary:
As part of the conversion to ETRS89 for national surveying within the
European Union, for example, the projection EPSG:25832 was used for
most of Germany. Unfortunately, the definition in the QGIS or PROJ.4
database shares the same parameters as EPSG:3044, so that shapefiles
(and maybe other formats, which don't have an explicite EPSG-tag)
that do not come from QGIS and are in EPSG:25832 are incorrectly
interpreted as EPSG:3044.

I was able to observe many users over the year, which do not correct
the projection neither for work within QGIS, nor for saving (they are
not aware of the problem) Worse still: when saving, EPSG:3044 is
written to the PRJ file (for shapefiles). Thus, the error manifests
itself permanently. There are also other

This, of course, also causes other problems: If a file has been
loaded into EPSG:3044 but a WMS does not know this projection, the
content  will not be displayed and/or there is an error message
(I had this several times in office).

This is probably related to the acutal (nearly outdated) PROJ.4 API
and might disappear when it is being updated (and integrated into
QGIS). Since EPSG:3044 comes earlier in the definition lists, QGIS
(or PROJ.4) machtes the first result and breaks.

Resulting problems:
On the one hand, this bug makes it difficult to interact with QGIS
and  other GIS (data exchange between different offices, authorities
and  companies) on a daily basis. On the other hand, it casts a bad
light  on QGIS itself... I am sure that the majority of QGIS users
do not understand that QGIS actually consists of many small libraries
(GDAL, PROJ. 4 etc.). Haters's will say: "priceless is useless".

Possible workaround:
We should check all SRS/CRS, where the parameters overlap. Then we
should order those "duplicates" by the frequency of use (for exaple
official projections first, follwed by historical projections).
Maybe  there's only a handful of projections that are affected.

Best regards,
Tobias