merge(3p/git): Merge git subtree at v2.29.2 r/1890

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

1 files changed, 91 insertions, 72 deletions

diff --git a/third_party/git/merge-recursive.h b/third_party/git/merge-recursive.h
index c2b7bb65c62f..0795a1d3ec18 100644
--- a/third_party/git/merge-recursive.h
+++ b/third_party/git/merge-recursive.h
@@ -1,104 +1,123 @@
 #ifndef MERGE_RECURSIVE_H
 #define MERGE_RECURSIVE_H
 
-#include "string-list.h"
-#include "unpack-trees.h"
+#include "strbuf.h"
 
 struct commit;
-
+struct commit_list;
+struct object_id;
 struct repository;
+struct tree;
 
+struct merge_options_internal;
 struct merge_options {
+	struct repository *repo;
+
+	/* ref names used in console messages and conflict markers */
 	const char *ancestor;
 	const char *branch1;
 	const char *branch2;
+
+	/* rename related options */
+	int detect_renames;
 	enum {
-		MERGE_RECURSIVE_NORMAL = 0,
-		MERGE_RECURSIVE_OURS,
-		MERGE_RECURSIVE_THEIRS
+		MERGE_DIRECTORY_RENAMES_NONE = 0,
+		MERGE_DIRECTORY_RENAMES_CONFLICT = 1,
+		MERGE_DIRECTORY_RENAMES_TRUE = 2
+	} detect_directory_renames;
+	int rename_limit;
+	int rename_score;
+	int show_rename_progress;
+
+	/* xdiff-related options (patience, ignore whitespace, ours/theirs) */
+	long xdl_opts;
+	enum {
+		MERGE_VARIANT_NORMAL = 0,
+		MERGE_VARIANT_OURS,
+		MERGE_VARIANT_THEIRS
 	} recursive_variant;
-	const char *subtree_shift;
+
+	/* console output related options */
+	int verbosity;
 	unsigned buffer_output; /* 1: output at end, 2: keep buffered */
+	struct strbuf obuf;     /* output buffer; if buffer_output == 2, caller
+				 * must handle and call strbuf_release */
+
+	/* miscellaneous control options */
+	const char *subtree_shift;
 	unsigned renormalize : 1;
-	long xdl_opts;
-	int verbosity;
-	int detect_directory_renames;
-	int diff_detect_rename;
-	int merge_detect_rename;
-	int diff_rename_limit;
-	int merge_rename_limit;
-	int rename_score;
-	int needed_rename_limit;
-	int show_rename_progress;
-	int call_depth;
-	struct strbuf obuf;
-	struct hashmap current_file_dir_set;
-	struct string_list df_conflict_file_set;
-	struct unpack_trees_options unpack_opts;
-	struct index_state orig_index;
-	struct repository *repo;
+
+	/* internal fields used by the implementation */
+	struct merge_options_internal *priv;
 };
 
+void init_merge_options(struct merge_options *opt, struct repository *repo);
+
+/* parse the option in s and update the relevant field of opt */
+int parse_merge_opt(struct merge_options *opt, const char *s);
+
 /*
- * For dir_rename_entry, directory names are stored as a full path from the
- * toplevel of the repository and do not include a trailing '/'.  Also:
- *
- *   dir:                original name of directory being renamed
- *   non_unique_new_dir: if true, could not determine new_dir
- *   new_dir:            final name of directory being renamed
- *   possible_new_dirs:  temporary used to help determine new_dir; see comments
- *                       in get_directory_renames() for details
+ * RETURN VALUES: All the merge_* functions below return a value as follows:
+ *   > 0     Merge was clean
+ *   = 0     Merge had conflicts
+ *   < 0     Merge hit an unexpected and unrecoverable problem (e.g. disk
+ *             full) and aborted merge part-way through.
  */
-struct dir_rename_entry {
-	struct hashmap_entry ent; /* must be the first member! */
-	char *dir;
-	unsigned non_unique_new_dir:1;
-	struct strbuf new_dir;
-	struct string_list possible_new_dirs;
-};
-
-struct collision_entry {
-	struct hashmap_entry ent; /* must be the first member! */
-	char *target_file;
-	struct string_list source_files;
-	unsigned reported_already:1;
-};
 
-static inline int merge_detect_rename(struct merge_options *o)
-{
-	return o->merge_detect_rename >= 0 ? o->merge_detect_rename :
-		o->diff_detect_rename >= 0 ? o->diff_detect_rename : 1;
-}
+/*
+ * rename-detecting three-way merge, no recursion.
+ *
+ * Outputs:
+ *   - See RETURN VALUES above
+ *   - opt->repo->index has the new index
+ *   - new index NOT written to disk
+ *   - The working tree is updated with results of the merge
+ */
+int merge_trees(struct merge_options *opt,
+		struct tree *head,
+		struct tree *merge,
+		struct tree *merge_base);
 
-/* merge_trees() but with recursive ancestor consolidation */
-int merge_recursive(struct merge_options *o,
+/*
+ * merge_recursive is like merge_trees() but with recursive ancestor
+ * consolidation.
+ *
+ * NOTE: empirically, about a decade ago it was determined that with more
+ *       than two merge bases, optimal behavior was found when the
+ *       merge_bases were passed in the order of oldest commit to newest
+ *       commit.  Also, merge_bases will be consumed (emptied) so make a
+ *       copy if you need it.
+ *
+ * Outputs:
+ *   - See RETURN VALUES above
+ *   - *result is treated as scratch space for temporary recursive merges
+ *   - opt->repo->index has the new index
+ *   - new index NOT written to disk
+ *   - The working tree is updated with results of the merge
+ */
+int merge_recursive(struct merge_options *opt,
 		    struct commit *h1,
 		    struct commit *h2,
-		    struct commit_list *ancestors,
+		    struct commit_list *merge_bases,
 		    struct commit **result);
 
-/* rename-detecting three-way merge, no recursion */
-int merge_trees(struct merge_options *o,
-		struct tree *head,
-		struct tree *merge,
-		struct tree *common,
-		struct tree **result);
-
 /*
- * "git-merge-recursive" can be fed trees; wrap them into
- * virtual commits and call merge_recursive() proper.
+ * merge_recursive_generic can operate on trees instead of commits, by
+ * wrapping the trees into virtual commits, and calling merge_recursive().
+ * It also writes out the in-memory index to disk if the merge is successful.
+ *
+ * Outputs:
+ *   - See RETURN VALUES above
+ *   - *result is treated as scratch space for temporary recursive merges
+ *   - opt->repo->index has the new index
+ *   - new index also written to $GIT_INDEX_FILE on disk
+ *   - The working tree is updated with results of the merge
  */
-int merge_recursive_generic(struct merge_options *o,
+int merge_recursive_generic(struct merge_options *opt,
 			    const struct object_id *head,
 			    const struct object_id *merge,
-			    int num_ca,
-			    const struct object_id **ca,
+			    int num_merge_bases,
+			    const struct object_id **merge_bases,
 			    struct commit **result);
 
-void init_merge_options(struct merge_options *o,
-			struct repository *repo);
-struct tree *write_tree_from_memory(struct merge_options *o);
-
-int parse_merge_opt(struct merge_options *out, const char *s);
-
 #endif