diff mbox series

[v3,06/11] merge_bases_many(): pass on errors from `paint_down_to_common()`

Message ID 2ae6a54dd596c3192b5be32f0e4e2605f4aac6bd.1709040499.git.gitgitgadget@gmail.com (mailing list archive)
State Superseded
Headers show
Series The merge-base logic vs missing commit objects | expand

Commit Message

Johannes Schindelin Feb. 27, 2024, 1:28 p.m. UTC
From: Johannes Schindelin <johannes.schindelin@gmx.de>

The `paint_down_to_common()` function was just taught to indicate
parsing errors, and now the `merge_bases_many()` function is aware of
that, too.

One tricky aspect is that `merge_bases_many()` parses commits of its
own, but wants to gracefully handle the scenario where NULL is passed as
a merge head, returning the empty list of merge bases. The way this was
handled involved calling `repo_parse_commit(NULL)` and relying on it to
return an error. This has to be done differently now so that we can
handle missing commits correctly by producing a fatal error.

Next step: adjust the caller of `merge_bases_many()`:
`get_merge_bases_many_0()`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 commit-reach.c | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

Comments

Junio C Hamano Feb. 27, 2024, 6:29 p.m. UTC | #1
"Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
writes:

> From: Johannes Schindelin <johannes.schindelin@gmx.de>
>
> The `paint_down_to_common()` function was just taught to indicate
> parsing errors, and now the `merge_bases_many()` function is aware of
> that, too.
>
> One tricky aspect is that `merge_bases_many()` parses commits of its
> own, but wants to gracefully handle the scenario where NULL is passed as
> a merge head, returning the empty list of merge bases. The way this was
> handled involved calling `repo_parse_commit(NULL)` and relying on it to
> return an error. This has to be done differently now so that we can
> handle missing commits correctly by producing a fatal error.
>
> Next step: adjust the caller of `merge_bases_many()`:
> `get_merge_bases_many_0()`.
>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
>  commit-reach.c | 35 ++++++++++++++++++++++-------------
>  1 file changed, 22 insertions(+), 13 deletions(-)

This is the true gem of the series.  The next steps may have to be
noisy due to many callers adjusting to the new function signatures,
but split into these logical steps in a bottom-up way makes them
easier to follow.  Nice.

>
> diff --git a/commit-reach.c b/commit-reach.c
> index 9148a7dcbc0..2c74583c8e0 100644
> --- a/commit-reach.c
> +++ b/commit-reach.c
> @@ -131,41 +131,49 @@ static int paint_down_to_common(struct repository *r,
>  	return 0;
>  }
>  
> -static struct commit_list *merge_bases_many(struct repository *r,
> -					    struct commit *one, int n,
> -					    struct commit **twos)
> +static int merge_bases_many(struct repository *r,
> +			    struct commit *one, int n,
> +			    struct commit **twos,
> +			    struct commit_list **result)
>  {
>  	struct commit_list *list = NULL;
> -	struct commit_list *result = NULL;
>  	int i;
>  
>  	for (i = 0; i < n; i++) {
> -		if (one == twos[i])
> +		if (one == twos[i]) {
>  			/*
>  			 * We do not mark this even with RESULT so we do not
>  			 * have to clean it up.
>  			 */
> -			return commit_list_insert(one, &result);
> +			*result = commit_list_insert(one, result);
> +			return 0;
> +		}
>  	}
>  
> +	if (!one)
> +		return 0;
>  	if (repo_parse_commit(r, one))
> -		return NULL;
> +		return error(_("could not parse commit %s"),
> +			     oid_to_hex(&one->object.oid));
>  	for (i = 0; i < n; i++) {
> +		if (!twos[i])
> +			return 0;
>  		if (repo_parse_commit(r, twos[i]))
> -			return NULL;
> +			return error(_("could not parse commit %s"),
> +				     oid_to_hex(&twos[i]->object.oid));
>  	}
>  
>  	if (paint_down_to_common(r, one, n, twos, 0, 0, &list) < 0) {
>  		free_commit_list(list);
> -		return NULL;
> +		return -1;
>  	}
>  
>  	while (list) {
>  		struct commit *commit = pop_commit(&list);
>  		if (!(commit->object.flags & STALE))
> -			commit_list_insert_by_date(commit, &result);
> +			commit_list_insert_by_date(commit, result);
>  	}
> -	return result;
> +	return 0;
>  }
>  
>  struct commit_list *get_octopus_merge_bases(struct commit_list *in)
> @@ -410,10 +418,11 @@ static struct commit_list *get_merge_bases_many_0(struct repository *r,
>  {
>  	struct commit_list *list;
>  	struct commit **rslt;
> -	struct commit_list *result;
> +	struct commit_list *result = NULL;
>  	int cnt, i;
>  
> -	result = merge_bases_many(r, one, n, twos);
> +	if (merge_bases_many(r, one, n, twos, &result) < 0)
> +		return NULL;
>  	for (i = 0; i < n; i++) {
>  		if (one == twos[i])
>  			return result;
diff mbox series

Patch

diff --git a/commit-reach.c b/commit-reach.c
index 9148a7dcbc0..2c74583c8e0 100644
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -131,41 +131,49 @@  static int paint_down_to_common(struct repository *r,
 	return 0;
 }
 
-static struct commit_list *merge_bases_many(struct repository *r,
-					    struct commit *one, int n,
-					    struct commit **twos)
+static int merge_bases_many(struct repository *r,
+			    struct commit *one, int n,
+			    struct commit **twos,
+			    struct commit_list **result)
 {
 	struct commit_list *list = NULL;
-	struct commit_list *result = NULL;
 	int i;
 
 	for (i = 0; i < n; i++) {
-		if (one == twos[i])
+		if (one == twos[i]) {
 			/*
 			 * We do not mark this even with RESULT so we do not
 			 * have to clean it up.
 			 */
-			return commit_list_insert(one, &result);
+			*result = commit_list_insert(one, result);
+			return 0;
+		}
 	}
 
+	if (!one)
+		return 0;
 	if (repo_parse_commit(r, one))
-		return NULL;
+		return error(_("could not parse commit %s"),
+			     oid_to_hex(&one->object.oid));
 	for (i = 0; i < n; i++) {
+		if (!twos[i])
+			return 0;
 		if (repo_parse_commit(r, twos[i]))
-			return NULL;
+			return error(_("could not parse commit %s"),
+				     oid_to_hex(&twos[i]->object.oid));
 	}
 
 	if (paint_down_to_common(r, one, n, twos, 0, 0, &list) < 0) {
 		free_commit_list(list);
-		return NULL;
+		return -1;
 	}
 
 	while (list) {
 		struct commit *commit = pop_commit(&list);
 		if (!(commit->object.flags & STALE))
-			commit_list_insert_by_date(commit, &result);
+			commit_list_insert_by_date(commit, result);
 	}
-	return result;
+	return 0;
 }
 
 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
@@ -410,10 +418,11 @@  static struct commit_list *get_merge_bases_many_0(struct repository *r,
 {
 	struct commit_list *list;
 	struct commit **rslt;
-	struct commit_list *result;
+	struct commit_list *result = NULL;
 	int cnt, i;
 
-	result = merge_bases_many(r, one, n, twos);
+	if (merge_bases_many(r, one, n, twos, &result) < 0)
+		return NULL;
 	for (i = 0; i < n; i++) {
 		if (one == twos[i])
 			return result;