Merge tag 'v2.25.0-rc0' into git-po-master

Git 2.25-rc0

* tag 'v2.25.0-rc0': (531 commits)
  Git 2.25-rc0
  sparse-checkout: improve OS ls compatibility
  dir.c: use st_add3() for allocation size
  dir: consolidate similar code in treat_directory()
  dir: synchronize treat_leading_path() and read_directory_recursive()
  dir: fix checks on common prefix directory
  t4015: improve coverage of function context test
  commit: forbid --pathspec-from-file --all
  t3434: mark successful test as such
  notes.h: fix typos in comment
  t6030: don't create unused file
  t5580: don't create unused file
  t3501: don't create unused file
  bisect--helper: convert `*_warning` char pointers to char arrays.
  The sixth batch
  fix-typo: consecutive-word duplications
  Makefile: drop GEN_HDRS
  built-in add -p: show helpful hint when nothing can be staged
  built-in add -p: only show the applicable parts of the help text
  built-in add -p: implement the 'q' ("quit") command
  ...

1 files changed, 32 insertions, 0 deletions

diff --git a/diffcore.h b/diffcore.h
index b651061c0e..7c07347e42 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -28,6 +28,12 @@ struct userdiff_driver;
 
 #define MINIMUM_BREAK_SIZE     400 /* do not break a file smaller than this */
 
+/**
+ * the internal representation for a single file (blob).  It records the blob
+ * object name (if known -- for a work tree file it typically is a NUL SHA-1),
+ * filemode and pathname.  This is what the `diff_addremove()`, `diff_change()`
+ * and `diff_unmerge()` synthesize and feed `diff_queue()` function with.
+ */
 struct diff_filespec {
 	struct object_id oid;
 	char *path;
@@ -66,6 +72,17 @@ void diff_free_filespec_data(struct diff_filespec *);
 void diff_free_filespec_blob(struct diff_filespec *);
 int diff_filespec_is_binary(struct repository *, struct diff_filespec *);
 
+/**
+ * This records a pair of `struct diff_filespec`; the filespec for a file in
+ * the "old" set (i.e. preimage) is called `one`, and the filespec for a file
+ * in the "new" set (i.e. postimage) is called `two`.  A change that represents
+ * file creation has NULL in `one`, and file deletion has NULL in `two`.
+ *
+ * A `filepair` starts pointing at `one` and `two` that are from the same
+ * filename, but `diffcore_std()` can break pairs and match component filespecs
+ * with other filespecs from a different filepair to form new filepair. This is
+ * called 'rename detection'.
+ */
 struct diff_filepair {
 	struct diff_filespec *one;
 	struct diff_filespec *two;
@@ -77,6 +94,7 @@ struct diff_filepair {
 	unsigned done_skip_stat_unmatch : 1;
 	unsigned skip_stat_unmatch_result : 1;
 };
+
 #define DIFF_PAIR_UNMERGED(p) ((p)->is_unmerged)
 
 #define DIFF_PAIR_RENAME(p) ((p)->renamed_pair)
@@ -94,11 +112,25 @@ void diff_free_filepair(struct diff_filepair *);
 
 int diff_unmodified_pair(struct diff_filepair *);
 
+/**
+ * This is a collection of filepairs.  Notable members are:
+ *
+ * - `queue`:
+ * An array of pointers to `struct diff_filepair`. This dynamically grows as
+ * you add filepairs;
+ *
+ * - `alloc`:
+ * The allocated size of the `queue` array;
+ *
+ * - `nr`:
+ * The number of elements in the `queue` array.
+ */
 struct diff_queue_struct {
 	struct diff_filepair **queue;
 	int alloc;
 	int nr;
 };
+
 #define DIFF_QUEUE_CLEAR(q) \
 	do { \
 		(q)->queue = NULL; \