doc: add documentation to all the public structs and enums

This makes them show up in the reference, even if the text itself isn't
the most descriptive.

These have been found with

    grep -Przon '\n\ntypedef struct.*?\{' -- include
    grep -Przon '\n\ntypedef enum.*?\{' -- include

include/git2/blame.h

@@ -67,7 +67,6 @@ typedef enum {
  *	- `max_line` is the last line in the file to blame.  The default is the last
  *	             line of the file.
  */
-
 typedef struct git_blame_options {
 	unsigned int version;
 

include/git2/cherrypick.h

@@ -20,14 +20,17 @@
  */
 GIT_BEGIN_DECL
 
+/**
+ * Cherry-pick options
+ */
 typedef struct {
 	unsigned int version;
 
 	/** For merge commits, the "mainline" is treated as the parent. */
 	unsigned int mainline;
 
-	git_merge_options merge_opts;
-	git_checkout_options checkout_opts;
+	git_merge_options merge_opts; /*< Options for the merging */
+	git_checkout_options checkout_opts; /*< Options for the checkout */
 } git_cherrypick_options;
 
 #define GIT_CHERRYPICK_OPTIONS_VERSION 1

include/git2/clone.h

@@ -100,7 +100,6 @@ typedef int (*git_repository_create_cb)(
  *
  *		git_clone_options opts = GIT_CLONE_OPTIONS_INIT;
  */
-
 typedef struct git_clone_options {
 	unsigned int version;
 

include/git2/common.h

@@ -123,7 +123,12 @@ typedef enum {
  */
 GIT_EXTERN(int) git_libgit2_features(void);
 
-
+/**
+ * Global library options
+ *
+ * These are used to select which global option to set or get and are
+ * used in `git_libgit2_opts()`.
+ */
 typedef enum {
 	GIT_OPT_GET_MWINDOW_SIZE,
 	GIT_OPT_SET_MWINDOW_SIZE,

include/git2/config.h

@@ -55,15 +55,21 @@ typedef enum {
 	GIT_CONFIG_HIGHEST_LEVEL = -1,
 } git_config_level_t;
 
+/**
+ * An entry in a configuration file
+ */
 typedef struct {
-	const char *name;
-	const char *value;
-	git_config_level_t level;
+	const char *name; /*< Name of the entry (normalised) */
+	const char *value; /*< String value of the entry */
+	git_config_level_t level; /*< Which config file this was found in */
 } git_config_entry;
 
 typedef int  (*git_config_foreach_cb)(const git_config_entry *, void *);
 typedef struct git_config_iterator git_config_iterator;
 
+/**
+ * Config var type
+ */
 typedef enum {
 	GIT_CVAR_FALSE = 0,
 	GIT_CVAR_TRUE = 1,
@@ -71,6 +77,9 @@ typedef enum {
 	GIT_CVAR_STRING
 } git_cvar_t;
 
+/**
+ * Mapping from config variables to values.
+ */
 typedef struct {
 	git_cvar_t cvar_type;
 	const char *str_match;

include/git2/filter.h

@@ -35,6 +35,9 @@ typedef enum {
 	GIT_FILTER_CLEAN = GIT_FILTER_TO_ODB,
 } git_filter_mode_t;
 
+/**
+ * Filter option flags.
+ */
 typedef enum {
 	GIT_FILTER_OPT_DEFAULT = 0u,
 	GIT_FILTER_OPT_ALLOW_UNSAFE = (1u << 0),

include/git2/index.h

@@ -75,6 +75,9 @@ typedef struct git_index_entry {
 #define GIT_IDXENTRY_STAGEMASK (0x3000)
 #define GIT_IDXENTRY_STAGESHIFT 12
 
+/**
+ * Flags for index entries
+ */
 typedef enum {
 	GIT_IDXENTRY_EXTENDED  = (0x4000),
 	GIT_IDXENTRY_VALID     = (0x8000),

include/git2/merge.h

@@ -110,20 +110,26 @@ typedef enum {
 	GIT_MERGE_FILE_FAVOR_UNION = 3,
 } git_merge_file_favor_t;
 
+/**
+ * File merging flags
+ */
 typedef enum {
-	/* Defaults */
+	/** Defaults */
 	GIT_MERGE_FILE_DEFAULT = 0,
 
-	/* Create standard conflicted merge files */
+	/** Create standard conflicted merge files */
 	GIT_MERGE_FILE_STYLE_MERGE = (1 << 0),
 
-	/* Create diff3-style files */
+	/** Create diff3-style files */
 	GIT_MERGE_FILE_STYLE_DIFF3 = (1 << 1),
 
-	/* Condense non-alphanumeric regions for simplified diff file */
+	/** Condense non-alphanumeric regions for simplified diff file */
 	GIT_MERGE_FILE_SIMPLIFY_ALNUM = (1 << 2),
 } git_merge_file_flags_t;
 
+/**
+ * Options for merging a file
+ */
 typedef struct {
 	unsigned int version;
 
@@ -168,6 +174,9 @@ GIT_EXTERN(int) git_merge_file_init_options(
 	git_merge_file_options *opts,
 	unsigned int version);
 
+/**
+ * Information about file-level merging
+ */
 typedef struct {
 	/**
 	 * True if the output was automerged, false if the output contains
@@ -191,6 +200,9 @@ typedef struct {
 	size_t len;
 } git_merge_file_result;
 
+/**
+ * Merging options
+ */
 typedef struct {
 	unsigned int version;
 	git_merge_tree_flag_t flags;
@@ -270,8 +282,11 @@ typedef enum {
 	GIT_MERGE_ANALYSIS_UNBORN = (1 << 3),
 } git_merge_analysis_t;
 
+/**
+ * The user's stated preference for merges.
+ */
 typedef enum {
-	/*
+	/**
 	 * No configuration was found that suggests a preferred behavior for
 	 * merge.
 	 */

include/git2/net.h

@@ -21,12 +21,13 @@ GIT_BEGIN_DECL
 
 #define GIT_DEFAULT_PORT "9418"
 
-/*
+/**
+ * Direction of the connection.
+ *
  * We need this because we need to know whether we should call
  * git-upload-pack or git-receive-pack on the remote end when get_refs
  * gets called.
  */
-
 typedef enum {
 	GIT_DIRECTION_FETCH = 0,
 	GIT_DIRECTION_PUSH  = 1

include/git2/rebase.h

@@ -21,6 +21,11 @@
  */
 GIT_BEGIN_DECL
 
+/**
+ * Rebase options
+ *
+ * Use to tell the rebase machinery how to operate.
+ */
 typedef struct {
 	unsigned int version;
 
@@ -40,7 +45,9 @@ typedef struct {
 	const char *rewrite_notes_ref;
 } git_rebase_options;
 
-/** Type of rebase operation in-progress after calling `git_rebase_next`. */
+/**
+ * Type of rebase operation in-progress after calling `git_rebase_next`.
+ */
 typedef enum {
 	/**
 	 * The given commit is to be cherry-picked.  The client should commit
@@ -82,6 +89,12 @@ typedef enum {
 #define GIT_REBASE_OPTIONS_VERSION 1
 #define GIT_REBASE_OPTIONS_INIT {GIT_REBASE_OPTIONS_VERSION}
 
+/**
+ * A rebase operation
+ *
+ * Describes a single instruction/operation to be performed during the
+ * rebase.
+ */
 typedef struct {
 	/** The type of rebase operation. */
 	git_rebase_operation_t type;

include/git2/refs.h

@@ -629,7 +629,13 @@ GIT_EXTERN(int) git_reference_is_tag(const git_reference *ref);
  */
 GIT_EXTERN(int) git_reference_is_note(const git_reference *ref);
 
+/**
+ * Normalization options for reference lookup
+ */
 typedef enum {
+	/**
+	 * No particular normalization.
+	 */
 	GIT_REF_FORMAT_NORMAL = 0u,
 
 	/**

include/git2/remote.h

@@ -555,6 +555,11 @@ GIT_EXTERN(const git_remote_callbacks *) git_remote_get_callbacks(git_remote *re
  */
 GIT_EXTERN(const git_transfer_progress *) git_remote_stats(git_remote *remote);
 
+/**
+ * Automatic tag following option
+ *
+ * Lets us select the --tags option to use.
+ */
 typedef enum {
 	GIT_REMOTE_DOWNLOAD_TAGS_AUTO = 0,
 	GIT_REMOTE_DOWNLOAD_TAGS_NONE = 1,

include/git2/repository.h

@@ -661,6 +661,12 @@ GIT_EXTERN(int) git_repository_detach_head(
 	const git_signature *signature,
 	const char *reflog_message);
 
+/**
+ * Repository state
+ *
+ * These values represent possible states for the repository to be in,
+ * based on the current operation which is ongoing.
+ */
 typedef enum {
 	GIT_REPOSITORY_STATE_NONE,
 	GIT_REPOSITORY_STATE_MERGE,

include/git2/revert.h

@@ -20,14 +20,17 @@
  */
 GIT_BEGIN_DECL
 
+/**
+ * Options for revert
+ */
 typedef struct {
 	unsigned int version;
 
 	/** For merge commits, the "mainline" is treated as the parent. */
 	unsigned int mainline;
 
-	git_merge_options merge_opts;
-	git_checkout_options checkout_opts;
+	git_merge_options merge_opts; /*< Options for the merging */
+	git_checkout_options checkout_opts; /*< Options for the checkout */
 } git_revert_options;
 
 #define GIT_REVERT_OPTIONS_VERSION 1

include/git2/stash.h

@@ -18,21 +18,30 @@
  */
 GIT_BEGIN_DECL
 
+/**
+ * Stash flags
+ */
 typedef enum {
+	/**
+	 * No option, default
+	 */
 	GIT_STASH_DEFAULT = 0,
 
-	/* All changes already added to the index
-	 * are left intact in the working directory
+	/**
+	 * All changes already added to the index are left intact in
+	 * the working directory
 	 */
 	GIT_STASH_KEEP_INDEX = (1 << 0),
 
-	/* All untracked files are also stashed and then
-	 * cleaned up from the working directory
+	/**
+	 * All untracked files are also stashed and then cleaned up
+	 * from the working directory
 	 */
 	GIT_STASH_INCLUDE_UNTRACKED = (1 << 1),
 
-	/* All ignored files are also stashed and then
-	 * cleaned up from the working directory
+	/**
+	 * All ignored files are also stashed and then cleaned up from
+	 * the working directory
 	 */
 	GIT_STASH_INCLUDE_IGNORED = (1 << 2),
 } git_stash_flags;

include/git2/sys/diff.h

@@ -61,10 +61,13 @@ GIT_EXTERN(int) git_diff_print_callback__to_file_handle(
 	void *payload); /*< payload must be a `FILE *` */
 
 
+/**
+ * Performance data from diffing
+ */
 typedef struct {
 	unsigned int version;
-	size_t stat_calls;
-	size_t oid_calculations;
+	size_t stat_calls; /*< Number of stat() calls performed */
+	size_t oid_calculations; /*< Number of ID calculations */
 } git_diff_perfdata;
 
 #define GIT_DIFF_PERFDATA_VERSION 1

include/git2/sys/hashsig.h

@@ -16,6 +16,9 @@ GIT_BEGIN_DECL
  */
 typedef struct git_hashsig git_hashsig;
 
+/**
+ * Options for hashsig calculation
+ */
 typedef enum {
 	GIT_HASHSIG_NORMAL = 0, /* use all data */
 	GIT_HASHSIG_IGNORE_WHITESPACE = 1, /* ignore whitespace */

include/git2/sys/transport.h

@@ -21,6 +21,11 @@
 
 GIT_BEGIN_DECL
 
+/**
+ * Flags to pass to transport
+ *
+ * Currently unused.
+ */
 typedef enum {
 	GIT_TRANSPORTFLAGS_NONE = 0,
 } git_transport_flags_t;
@@ -286,12 +291,20 @@ typedef int (*git_smart_subtransport_cb)(
 	git_smart_subtransport **out,
 	git_transport* owner);
 
+/**
+ * Definition for a "subtransport"
+ *
+ * This is used to let the smart protocol code know about the protocol
+ * which you are implementing.
+ */
 typedef struct git_smart_subtransport_definition {
-	/* The function to use to create the git_smart_subtransport */
+	/** The function to use to create the git_smart_subtransport */
 	git_smart_subtransport_cb callback;
 
-	/* True if the protocol is stateless; false otherwise. For example,
-	 * http:// is stateless, but git:// is not. */
+	/**
+	 * True if the protocol is stateless; false otherwise. For example,
+	 * http:// is stateless, but git:// is not.
+	 */
 	unsigned rpc;
 } git_smart_subtransport_definition;