Re: [PATCH v4 24/27] builtin/rebase: do not assign default backend to non-constant field

> The `struct rebase_options::default_backend` field is a non-constant
> string, but is being assigned a constant via `REBASE_OPTIONS_INIT`.
> Refactor the code to initialize and release options via two functions
> `rebase_options_init()` and `rebase_options_release()`. Like this, we
> can easily adapt the former funnction to use `xstrdup()` on the default
> value without hiding it away in a macro.

> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>   builtin/rebase.c | 67 ++++++++++++++++++++++++++++--------------------
>   1 file changed, 39 insertions(+), 28 deletions(-)
> 
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 14d4f0a5e6..11f276012c 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -131,25 +131,40 @@ struct rebase_options {
>   	int config_update_refs;
>   };
>   
> -#define REBASE_OPTIONS_INIT {			  	\
> -		.type = REBASE_UNSPECIFIED,	  	\
> -		.empty = EMPTY_UNSPECIFIED,	  	\
> -		.keep_empty = 1,			\
> -		.default_backend = "merge",	  	\
> -		.flags = REBASE_NO_QUIET, 		\
> -		.git_am_opts = STRVEC_INIT,		\
> -		.exec = STRING_LIST_INIT_NODUP,		\
> -		.git_format_patch_opt = STRBUF_INIT,	\
> -		.fork_point = -1,			\
> -		.reapply_cherry_picks = -1,             \
> -		.allow_empty_message = 1,               \
> -		.autosquash = -1,                       \
> -		.rebase_merges = -1,                    \
> -		.config_rebase_merges = -1,             \
> -		.update_refs = -1,                      \
> -		.config_update_refs = -1,               \
> -		.strategy_opts = STRING_LIST_INIT_NODUP,\
> -	}
> +static void rebase_options_init(struct rebase_options *opts)
> +{
> +	memset(opts, 0, sizeof(*opts));
> +	opts->type = REBASE_UNSPECIFIED;
> +	opts->empty = EMPTY_UNSPECIFIED;
> +	opts->default_backend = xstrdup("merge");
> +	opts->keep_empty = 1;
> +	opts->flags = REBASE_NO_QUIET;
> +	strvec_init(&opts->git_am_opts);
> +	string_list_init_nodup(&opts->exec);
> +	strbuf_init(&opts->git_format_patch_opt, 0);
> +	opts->fork_point = -1;
> +	opts->reapply_cherry_picks = -1;
> +	opts->allow_empty_message = 1;
> +	opts->autosquash = -1;
> +	opts->rebase_merges = -1;
> +	opts->config_rebase_merges = -1;
> +	opts->update_refs = -1;
> +	opts->config_update_refs = -1;
> +	string_list_init_nodup(&opts->strategy_opts);
> +}
> +
> +static void rebase_options_release(struct rebase_options *opts)
> +{
> +	free(opts->default_backend);
> +	free(opts->reflog_action);
> +	free(opts->head_name);
> +	strvec_clear(&opts->git_am_opts);
> +	free(opts->gpg_sign_opt);
> +	string_list_clear(&opts->exec, 0);
> +	free(opts->strategy);
> +	string_list_clear(&opts->strategy_opts, 0);
> +	strbuf_release(&opts->git_format_patch_opt);
> +}
>   
>   static struct replay_opts get_replay_opts(const struct rebase_options *opts)
>   {
> @@ -796,6 +811,7 @@ static int rebase_config(const char *var, const char *value,
>   	}
>   
>   	if (!strcmp(var, "rebase.backend")) {
> +		FREE_AND_NULL(opts->default_backend);
>   		return git_config_string(&opts->default_backend, var, value);
>   	}
>   
> @@ -1045,7 +1061,7 @@ static int check_exec_cmd(const char *cmd)
>   
>   int cmd_rebase(int argc, const char **argv, const char *prefix)
>   {
> -	struct rebase_options options = REBASE_OPTIONS_INIT;
> +	struct rebase_options options;
>   	const char *branch_name;
>   	int ret, flags, total_argc, in_progress = 0;
>   	int keep_base = 0;
> @@ -1178,6 +1194,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   	};
>   	int i;
>   
> +	rebase_options_init(&options);
> +
>   	if (argc == 2 && !strcmp(argv[1], "-h"))
>   		usage_with_options(builtin_rebase_usage,
>   				   builtin_rebase_options);
> @@ -1833,14 +1851,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
>   cleanup:
>   	strbuf_release(&buf);
>   	strbuf_release(&revisions);
> -	free(options.reflog_action);
> -	free(options.head_name);
> -	strvec_clear(&options.git_am_opts);
> -	free(options.gpg_sign_opt);
> -	string_list_clear(&options.exec, 0);
> -	free(options.strategy);
> -	string_list_clear(&options.strategy_opts, 0);
> -	strbuf_release(&options.git_format_patch_opt);
> +	rebase_options_release(&options);
>   	free(squash_onto_name);
>   	free(keep_base_onto_name);
>   	return !!ret;