"Elijah Newren via GitGitGadget" <gitgitgadget@xxxxxxxxx> writes:
> From: Elijah Newren <newren@xxxxxxxxx>
>
> Commit 4057523a40 ("submodule merge: update conflict error message",
> 2022-08-04) added a sub_flag variable that is used to store a value from
> enum conflict_and_info_types, but initializes it with an invalid value
> of -1. The code may never set it to a valid value, and use the invalid
> one. This can be surprising when reading over the code at first, but it
> was intentional. Add a comment making it clear that it is okay to be
> using an invalid value, due to how it is used later.
The current code uses -1 as the "suggest the default course of
action", so -1 is very much a "valid value" from the viewpoint of
the code that suggests how to resolve. It indeed is an invalid
value from the viewpoint of those who maintain conflict_and_info_types
enum.
> Signed-off-by: Elijah Newren <newren@xxxxxxxxx>
> ---
> merge-ort.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/merge-ort.c b/merge-ort.c
> index 67159fc6ef9..0a935a8135f 100644
> --- a/merge-ort.c
> +++ b/merge-ort.c
> @@ -1886,7 +1886,7 @@ cleanup:
> const char *abbrev;
>
> util = xmalloc(sizeof(*util));
> - util->flag = sub_flag;
> + util->flag = sub_flag; /* May still be -1 */
> util->abbrev = NULL;
> if (!sub_not_initialized) {
> abbrev = repo_find_unique_abbrev(&subrepo, b, DEFAULT_ABBREV);
This new comment may be a slight improvement, but a valid value of
sub_flag is used only to signal the situation where the code does
not know what to suggest, which feels backwards for longer-term code
evolution. Presumably, we would use the util->flag field to store
which of the known cases we know what to suggest as we know better.
I wonder if we should initialize the variable to the most generic
CONFLICT_SUBMODULE_FAILED_TO_MERGE instead of -1. The value would
mean "use the default suggestion", and the two known unworkable
values (not-initialized and history-not-available) are currently
handled according to what these two values mean. We may later add
more specialization based on other CONFLICT_SUBMODULE_* values.
Thanks.
