Heads up: I'm going to add typedef apr_array_header_t svn_merge_rangelist_t;
There's no major impact; it doesn't change anything functionally. The rest of the details: The immediate reason is to improve the debugging experience: I can then make GDB display 'rangelist' values in a simple human-readable form, whereas presently the best it can do is recognize that it is an APR array and display something like "array of 2 items". Beyond that, it makes sense from a coding abstraction point of view: it fills in the gap in this hierarchy of types (quoting from svn_mergeinfo.h): /** Terminology for data structures that contain mergeinfo. * * Subversion commonly uses several data structures to represent * mergeinfo in RAM: * * (a) Strings (@c svn_string_t *) containing "unparsed mergeinfo". * * (b) A "rangelist". An array (@c apr_array_header_t *) of non-overlapping * merge ranges (@c svn_merge_range_t *), sorted as said by * @c svn_sort_compare_ranges(). An empty range list is [...]. * * (c) @c svn_mergeinfo_t, called "mergeinfo". A hash mapping merge * source paths (@c const char *, starting with slashes) to * non-empty rangelist arrays. A @c NULL hash is used to [...]. * * (d) @c svn_mergeinfo_catalog_t, called a "mergeinfo catalog". A hash * mapping paths (@c const char *) to @c svn_mergeinfo_t. * * Both @c svn_mergeinfo_t and @c svn_mergeinfo_catalog_t are just * typedefs for @c apr_hash_t *; there is no static type-checking, and * you still use standard @c apr_hash_t functions to interact with * them. [...] */ typedef apr_hash_t *svn_mergeinfo_t; typedef apr_hash_t *svn_mergeinfo_catalog_t; The new type will be public. Because it's just a typedef, the C API will be backward-compatible and it won't change the ABI. (Can someone confirm that?) As mentioned in that doc string, using such a typedef doesn't provide any static type-checking. svn_merge_rangelist_t is not going to be a pointer like svn_mergeinfo_t and svn_mergeinfo_catalog_t are, since that is a poor idiom leading to inability to declare a parameter as "pointer to a const rangelist". - Julian
