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Re: [PATCH 2/2] parse-options: adjust `parse_opt_unknown_cb()`s declared return type




"Johannes Schindelin via GitGitGadget" <gitgitgadget@xxxxxxxxx>
writes:

> From: Johannes Schindelin <johannes.schindelin@xxxxxx>
>
> In f41179f16ba2 (parse-options: avoid magic return codes, 2019-01-27),
> the signature of the low-level parse-opt callback function was changed
> to return an `enum`.
>
> And while the implementations were changed, one declaration was left
> unchanged, still claiming to return `int`.
>
> This can potentially lead to problems, as compilers are free to choose
> any integral type for an `enum` as long as it can represent all declared
> values.

The enum is meant to represent "these magic negative numbers", and
if the compiler chose "long" for it and the implementation of the
function returned a "long", while the caller thought it would yield
an "int", things will break.

Looks good to make callers' expectation and what callee does
consistent.

>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
> ---
>  parse-options.h | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/parse-options.h b/parse-options.h
> index bd00cf0049..cd756833a9 100644
> --- a/parse-options.h
> +++ b/parse-options.h
> @@ -286,7 +286,9 @@ int parse_opt_commit(const struct option *, const char *, int);
>  int parse_opt_tertiary(const struct option *, const char *, int);
>  int parse_opt_string_list(const struct option *, const char *, int);
>  int parse_opt_noop_cb(const struct option *, const char *, int);
> -int parse_opt_unknown_cb(struct parse_opt_ctx_t *ctx, const struct option *, const char *, int);
> +enum parse_opt_result parse_opt_unknown_cb(struct parse_opt_ctx_t *ctx,
> +					   const struct option *,
> +					   const char *, int);
>  int parse_opt_passthru(const struct option *, const char *, int);
>  int parse_opt_passthru_argv(const struct option *, const char *, int);