Error management: revise error codes and expose them to the public API

[rouault]

Fixes #2482

Three classes of errors are defined:

/** Error codes typically related to coordinate operation initalization
 * Note: some of them can also be emitted during coordinate transformation,
 * like PROJ_ERR_INVALID_OP_FILE_NOT_FOUND_OR_INVALID in case the resource loading
 * is differed until it is really needed.
 */
#define PROJ_ERR_INVALID_OP                           1024                        /* other/unspecified error related to coordinate operation initialization */
#define PROJ_ERR_INVALID_OP_WRONG_SYNTAX              (PROJ_ERR_INVALID_OP+1)     /* invalid pipeline structure, missing +proj argument, etc */
#define PROJ_ERR_INVALID_OP_MISSING_ARG               (PROJ_ERR_INVALID_OP+2)     /* missing required operation parameter */
#define PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE         (PROJ_ERR_INVALID_OP+3)     /* one of the operation parameter has an illegal value */
#define PROJ_ERR_INVALID_OP_MUTUALLY_EXCLUSIVE_ARGS   (PROJ_ERR_INVALID_OP+4)     /* mutually exclusive arguments */
#define PROJ_ERR_INVALID_OP_FILE_NOT_FOUND_OR_INVALID (PROJ_ERR_INVALID_OP+5)     /* file not found (particular case of PROJ_ERR_INVALID_OP_ILLEGAL_ARG_VALUE) */

/** Error codes related to transformation on a specific coordinate */
#define PROJ_ERR_COORD_TRANSFM                           2048                           /* other error related to coordinate transformation */
#define PROJ_ERR_COORD_TRANSFM_INVALID_COORD             (PROJ_ERR_COORD_TRANSFM+1)     /* for e.g lat > 90deg */
#define PROJ_ERR_COORD_TRANSFM_OUTSIDE_PROJECTION_DOMAIN (PROJ_ERR_COORD_TRANSFM+2)     /* coordinate is outside of the projection domain. e.g approximate mercator with |longitude - lon_0| > 90deg, or iterative convergence method failed */
#define PROJ_ERR_COORD_TRANSFM_NO_OPERATION              (PROJ_ERR_COORD_TRANSFM+3)     /* no operation found, e.g if no match the required accuracy, or if ballpark transformations were asked to not be used and they would be only such candidate */
#define PROJ_ERR_COORD_TRANSFM_OUTSIDE_GRID              (PROJ_ERR_COORD_TRANSFM+4)     /* point to transform falls outside grid or subgrid */
#define PROJ_ERR_COORD_TRANSFM_GRID_AT_NODATA            (PROJ_ERR_COORD_TRANSFM+5)     /* point to transform falls in a grid cell that evaluates to nodata */

/** Other type of errors */
#define PROJ_ERR_OTHER                                   4096
#define PROJ_ERR_OTHER_API_MISUSE                        (PROJ_ERR_OTHER+1)             /* error related to a misuse of PROJ API */
#define PROJ_ERR_OTHER_NO_INVERSE_OP                     (PROJ_ERR_OTHER+2)             /* no inverse method available */
#define PROJ_ERR_OTHER_NETWORK_ERROR                     (PROJ_ERR_OTHER+3)             /* failure when accessing a network resource */

And also add proj_context_errno_string()

Revise gie 'expect failure errno XXXX' strings

Other related changes:

• Move proj_log_XXX() functions from internal.cpp to log.cpp
• Remove ancient no longer used implementation of pj_ell_set()
• tmerc exact: set errno to PROJ_ERR_COORD_TRANSFM_OUTSIDE_PROJECTION_DOMAIN when it returns invalid coordinate
• proj_trans_array(): make it transform all coordinates even when an error occurs

[kbevers]

There's a lot go through here. For this initial review I've only added a few comments in the start. Some of them will be relevant throughout the PR since they are a bit fundamental to how errors and loggin should be handled.

God job so far. It's a big project to change all of this to the better!

[rouault]

@kbevers Do you wish to review more things in this PR ?

[kbevers]

No, I think this looks good as it is!