[Question] Replacing enums

[lnicola]

I'm trying to produce bindings that support multiple versions of a library. It generally went smoothly, but I hit a snag. The library used to have this definition:

typedef int OGRErr;

#define OGRERR_NONE                0
#define OGRERR_NOT_ENOUGH_DATA     1    /* not enough data to deserialize */
#define OGRERR_NOT_ENOUGH_MEMORY   2
#define OGRERR_UNSUPPORTED_GEOMETRY_TYPE 3
#define OGRERR_UNSUPPORTED_OPERATION 4
#define OGRERR_CORRUPT_DATA        5
#define OGRERR_FAILURE             6
#define OGRERR_UNSUPPORTED_SRS     7
#define OGRERR_INVALID_HANDLE      8

which was later replaced by:

#ifdef STRICT_OGRERR_TYPE
/** Type for a OGR error */
typedef enum
{
    OGRERR_NONE,                       /**< Success */
    OGRERR_NOT_ENOUGH_DATA,            /**< Not enough data to deserialize */
    OGRERR_NOT_ENOUGH_MEMORY,          /**< Not enough memory */
    OGRERR_UNSUPPORTED_GEOMETRY_TYPE,  /**< Unsupported geometry type */
    OGRERR_UNSUPPORTED_OPERATION,      /**< Unsupported operation */
    OGRERR_CORRUPT_DATA,               /**< Corrupt data */
    OGRERR_FAILURE,                    /**< Failure */
    OGRERR_UNSUPPORTED_SRS,            /**< Unsupported SRS */
    OGRERR_INVALID_HANDLE,             /**< Invalid handle */
    OGRERR_NON_EXISTING_FEATURE        /**< Non existing feature. Added in GDAL 2.0 */
} OGRErr;
#else
/** Type for a OGR error */
typedef int OGRErr;

#define OGRERR_NONE                0       /**< Success */
#define OGRERR_NOT_ENOUGH_DATA     1       /**< Not enough data to deserialize */
#define OGRERR_NOT_ENOUGH_MEMORY   2       /**< Not enough memory */
#define OGRERR_UNSUPPORTED_GEOMETRY_TYPE 3 /**< Unsupported geometry type */
#define OGRERR_UNSUPPORTED_OPERATION 4     /**< Unsupported operation */
#define OGRERR_CORRUPT_DATA        5       /**< Corrupt data */
#define OGRERR_FAILURE             6       /**< Failure */
#define OGRERR_UNSUPPORTED_SRS     7       /**< Unsupported SRS */
#define OGRERR_INVALID_HANDLE      8       /**< Invalid handle */
#define OGRERR_NON_EXISTING_FEATURE 9      /**< Non existing feature. Added in GDAL 2.0 */

#endif

The other enumerations in the library really are enums. I used the constified_enum_module option for them, and I wanted to also use it for the one above. However, I can't find a way to produce code that works with both versions of the library.

One approach I tried was to provide a replacement for the OGRErr definition:

/**
 * <div rustbindgen replaces="OGRErr"></div>
 */
typedef enum
{
    OGRERR_NONE,                       /**< Success */
    OGRERR_NOT_ENOUGH_DATA,            /**< Not enough data to deserialize */
    OGRERR_NOT_ENOUGH_MEMORY,          /**< Not enough memory */
    OGRERR_UNSUPPORTED_GEOMETRY_TYPE,  /**< Unsupported geometry type */
    OGRERR_UNSUPPORTED_OPERATION,      /**< Unsupported operation */
    OGRERR_CORRUPT_DATA,               /**< Corrupt data */
    OGRERR_FAILURE,                    /**< Failure */
    OGRERR_UNSUPPORTED_SRS,            /**< Unsupported SRS */
    OGRERR_INVALID_HANDLE,             /**< Invalid handle */
    OGRERR_NON_EXISTING_FEATURE        /**< Non existing feature. Added in GDAL 2.0 */
} StrictOGRErr;

But that doesn't work because it redefines the enum values and rustbingen replaces doesn't seem to consider them:

/**
 * <div rustbindgen replaces="OGRErr"></div>
 */
typedef enum
{
    /**
    * <div rustbindgen replaces="OGRERR_NONE"></div>
    */
    STRICT_OGRERR_NONE                       /**< Success */
} StrictOGRErr;

produces:

pub mod OGRErr {
    /// <div rustbindgen replaces="OGRErr"></div>
    pub type Type = u32;
    /// < Success
    pub const STRICT_OGRERR_NONE: Type = 0;
}

Is there a better way to do this?

[emilio]

I guess the issue why you need to use STRICT_OGRERR_NONE instead of just OGRERR_NONE is because otherwise the C code doesn't build due to name clashes? That's indeed annoying :(.

We can add an annotation to rename enum variants, would that work for you?

[lnicola]

Yes, I think that would work.

[emilio]

#1268 Should fix it. Feel free to give it a try if you want until it gets review :)