Remove support for PROJ < 6

Require PROJ >= 6.1 (6.0 was not supported)
6.1 was released in May 2019, 4 years ago. None of our CI tests PROJ < 6
anymore.

cmake/FindProj.cmake

@@ -6,7 +6,7 @@
 #    PROJ_LIBRARY
 
 
-FIND_PATH(PROJ_INCLUDE_DIR NAMES proj.h proj_api.h)
+FIND_PATH(PROJ_INCLUDE_DIR NAMES proj.h)
 
 FIND_LIBRARY(PROJ_LIBRARY NAMES proj proj_i)
 
@@ -20,21 +20,19 @@ IF (PROJ_INCLUDE_DIR AND PROJ_LIBRARY)
 ENDIF (PROJ_INCLUDE_DIR AND PROJ_LIBRARY)
 
 IF (PROJ_FOUND)
-   IF (EXISTS ${PROJ_INCLUDE_DIR}/proj.h)
      FILE(READ ${PROJ_INCLUDE_DIR}/proj.h proj_version)
      STRING(REGEX REPLACE "^.*PROJ_VERSION_MAJOR +([0-9]+).*$" "\\1" PROJ_VERSION_MAJOR "${proj_version}")
      STRING(REGEX REPLACE "^.*PROJ_VERSION_MINOR +([0-9]+).*$" "\\1" PROJ_VERSION_MINOR "${proj_version}")
      STRING(REGEX REPLACE "^.*PROJ_VERSION_PATCH +([0-9]+).*$" "\\1" PROJ_VERSION_PATCH "${proj_version}")
 
      MESSAGE(STATUS "Found Proj ${PROJ_VERSION_MAJOR}.${PROJ_VERSION_MINOR}")
 
+     IF (PROJ_VERSION_MAJOR EQUAL 6 AND PROJ_VERSION_MINOR EQUAL 0)
+        MESSAGE (FATAL_ERROR "PROJ 6.0 is not supported. Use 6.1.0 or higher.")
+     ENDIF()
      IF ((PROJ_VERSION_MAJOR EQUAL 6) AND (PROJ_VERSION_MINOR EQUAL 3) AND (PROJ_VERSION_PATCH EQUAL 0))
         MESSAGE (FATAL_ERROR "MapServer known to crash with PROJ 6.3.0. Use 6.3.1 or higher.")
-     ENDIF ((PROJ_VERSION_MAJOR EQUAL 6) AND (PROJ_VERSION_MINOR EQUAL 3) AND (PROJ_VERSION_PATCH EQUAL 0))
+     ENDIF()
 
      ADD_DEFINITIONS(-DPROJ_VERSION_MAJOR=${PROJ_VERSION_MAJOR})
-  ELSE()
-     MESSAGE(STATUS "Found Proj 4.x")
-     ADD_DEFINITIONS(-DPROJ_VERSION_MAJOR=4)
-  ENDIF()
 ENDIF (PROJ_FOUND)

mapogr.cpp

@@ -1000,9 +1000,7 @@ static int msOGRSpatialRef2ProjectionObj(OGRSpatialReferenceH hSRS,
     return MS_SUCCESS;
   }
 
-#if PROJ_VERSION_MAJOR >= 6
-  // This could be done also in the < 6 case, but would be useless.
-  // Here this helps avoiding going through potentially lossy PROJ4 strings
+  // This helps avoiding going through potentially lossy PROJ4 strings
   const char* pszAuthName = OSRGetAuthorityName(hSRS, NULL);
   if( pszAuthName && EQUAL(pszAuthName, "EPSG") )
   {
@@ -1018,7 +1016,6 @@ static int msOGRSpatialRef2ProjectionObj(OGRSpatialReferenceH hSRS,
         return msLoadProjectionString(proj, szInitStr) == 0 ? MS_SUCCESS : MS_FAILURE;
     }
   }
-#endif
 
   // Export OGR SRS to a PROJ4 string
   char *pszProj = NULL;