Simplified merge logic

PATCH In review Seija K. via GitGitGadget 2 participants 4 messages Nov 8, 2020 – Nov 17, 2020

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Seija K. via GitGitGadget

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2020-11-08 21:39 UTC #0 lore raw

PATCH 1/1 Simplified merge logic

From: pi1024e <[email protected]>

commit: Avoid extraneous boolean checking by simplifying the if statements.

Signed-off-by Seija <[email protected]>

---
Simplified merge logic

The logic for the merging is somewhat confusing. So I simplified it to be equivalent. I tested all my changes to ensure in practice they work.

The first thing I did was test out which branch would occur for every possible value of

remoteheads->nextcommon->nextoption_commitBranchTTTATTFATFTATFFAFTTCFTFC FFTBFFFAUsing this truth table, I was able to deduce that if the second branch ran, the if statement for the first branch was false. Taking the inverse, it was then found many of the checks were redundant, so the if statement was rewritten to have each branch run under the same exact conditions, except each value is evaluated as little as possible.

I hope you can approve of this and show me how to send it.

Thank you.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-911%2Fpi1024e%2Fmerge-cleanup-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-911/pi1024e/merge-cleanup-v1
Pull-Request: https://github.com/git/git/pull/911

 builtin/merge.c | 85 ++++++++++++++++++++++---------------------------
 1 file changed, 38 insertions(+), 47 deletions(-)

builtin/merge.c +38 ~~-47~~

index 4c133402a6..9664da6031 100644
@@ -853,9 +853,8 @@ static void prepare_to_commit(struct commit_list *remoteheads)
 	if (run_commit_hook(0 < option_edit, get_index_file(), "prepare-commit-msg",
 			    git_path_merge_msg(the_repository), "merge", NULL))
 		abort_commit(remoteheads, NULL);
-	if (0 < option_edit) {
-		if (launch_editor(git_path_merge_msg(the_repository), NULL, NULL))
-			abort_commit(remoteheads, NULL);
+	if (0 < option_edit && launch_editor(git_path_merge_msg(the_repository), NULL, NULL)) {
+		abort_commit(remoteheads, NULL);
 	}
 
 	if (!no_verify && run_commit_hook(0 < option_edit, get_index_file(),

@@ -1213,7 +1212,7 @@ static int merging_a_throwaway_tag(struct commit *commit)
 	if (!merge_remote_util(commit) ||
 	    !merge_remote_util(commit)->obj ||
 	    merge_remote_util(commit)->obj->type != OBJ_TAG)
-		return is_throwaway_tag;
+		return 0;
 
 	/*
 	 * Now we know we are merging a tag object.  Are we downstream

@@ -1459,13 +1458,12 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			fast_forward = FF_NO;
 	}
 
-	if (!use_strategies) {
-		if (!remoteheads)
-			; /* already up-to-date */
-		else if (!remoteheads->next)
-			add_strategies(pull_twohead, DEFAULT_TWOHEAD);
-		else
+	if (!use_strategies && remoteheads) {
+		/* not up-to-date */
+		if (remoteheads->next)
 			add_strategies(pull_octopus, DEFAULT_OCTOPUS);
+		else
+			add_strategies(pull_twohead, DEFAULT_TWOHEAD);
 	}
 
 	for (i = 0; i < use_strategies_nr; i++) {

@@ -1475,15 +1473,15 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			allow_trivial = 0;
 	}
 
-	if (!remoteheads)
-		; /* already up-to-date */
-	else if (!remoteheads->next)
-		common = get_merge_bases(head_commit, remoteheads->item);
-	else {
-		struct commit_list *list = remoteheads;
-		commit_list_insert(head_commit, &list);
-		common = get_octopus_merge_bases(list);
-		free(list);
+	if (remoteheads) {
+		/* not up-to-date */
+		if (remoteheads->next) {
+			struct commit_list *list = remoteheads;
+			commit_list_insert(head_commit, &list);
+			common = get_octopus_merge_bases(list);
+			free(list);
+		} else
+			common = get_merge_bases(head_commit, remoteheads->item);
 	}
 
 	update_ref("updating ORIG_HEAD", "ORIG_HEAD",

@@ -1542,31 +1540,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		finish(head_commit, remoteheads, &commit->object.oid, msg.buf);
 		remove_merge_branch_state(the_repository);
 		goto done;
-	} else if (!remoteheads->next && common->next)
-		;
-		/*
-		 * We are not doing octopus and not fast-forward.  Need
-		 * a real merge.
-		 */
-	else if (!remoteheads->next && !common->next && option_commit) {
-		/*
-		 * We are not doing octopus, not fast-forward, and have
-		 * only one common.
-		 */
-		refresh_cache(REFRESH_QUIET);
-		if (allow_trivial && fast_forward != FF_ONLY) {
-			/* See if it is really trivial. */
-			git_committer_info(IDENT_STRICT);
-			printf(_("Trying really trivial in-index merge...\n"));
-			if (!read_tree_trivial(&common->item->object.oid,
-					       &head_commit->object.oid,
-					       &remoteheads->item->object.oid)) {
-				ret = merge_trivial(head_commit, remoteheads);
-				goto done;
-			}
-			printf(_("Nope.\n"));
-		}
-	} else {
+	} else if (remoteheads->next || (!common->next && !option_commit)) {
 		/*
 		 * An octopus.  If we can reach all the remote we are up
 		 * to date.

@@ -1592,6 +1566,24 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			finish_up_to_date(_("Already up to date. Yeeah!"));
 			goto done;
 		}
+	} else if (!common->next) {
+		/*
+		 * We are not doing octopus, not fast-forward, and have
+		 * only one common.
+		 */
+		refresh_cache(REFRESH_QUIET);
+		if (allow_trivial && fast_forward != FF_ONLY) {
+			/* See if it is really trivial. */
+			git_committer_info(IDENT_STRICT);
+			printf(_("Trying really trivial in-index merge...\n"));
+			if (!read_tree_trivial(&common->item->object.oid,
+					       &head_commit->object.oid,
+					       &remoteheads->item->object.oid)) {
+				ret = merge_trivial(head_commit, remoteheads);
+				goto done;
+			}
+			printf(_("Nope.\n"));
+		}
 	}
 
 	if (fast_forward == FF_ONLY)

@@ -1685,9 +1677,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 				use_strategies[0]->name);
 		ret = 2;
 		goto done;
-	} else if (best_strategy == wt_strategy)
-		; /* We already have its result in the working tree. */
-	else {
+	} else if (best_strategy != wt_strategy) {
+		/* We do not have its result in the working tree. */
 		printf(_("Rewinding the tree to pristine...\n"));
 		restore_state(&head_commit->object.oid, &stash);
 		printf(_("Using the %s to prepare resolving by hand.\n"),

base-commit: 7f7ebe054af6d831b999d6c2241b9227c4e4e08d

Signature · 1 line

gitgitgadget

Junio C Hamano

2020-11-09 23:17 UTC #1 lore raw

Quoted 5 lines · Seija K. via GitGitGadget

From: pi1024e <[email protected]>
commit: Avoid extraneous boolean checking by simplifying the if statements.
Signed-off-by Seija <[email protected]>
---

Meh.

Admittedly, readability is somewhat subjective, but a rewrite like

        if (condition)                  if (!condition)
                do_when_true();                 do_when_false();
        else                       ==>  else
                do_when_false();                do_when_true();

while it may not be incorrect per-se needs more than a subjective "I think this is more readable" to justify the code churn.

Quoted 5 lines

builtin/merge.c +0 -0
index 4c133402a6..9664da6031 100644

builtin/merge.c static void prepare_to_commit(struct commit_list *remoteheads) · line 858

Quoted 9 lines

builtin/merge.c +2 -3

@@ -853,9 +853,8 @@ static void prepare_to_commit(struct commit_list *remoteheads)
 	if (run_commit_hook(0 < option_edit, get_index_file(), "prepare-commit-msg",
 			    git_path_merge_msg(the_repository), "merge", NULL))
 		abort_commit(remoteheads, NULL);
-	if (0 < option_edit) {
-		if (launch_editor(git_path_merge_msg(the_repository), NULL, NULL))
-			abort_commit(remoteheads, NULL);
+	if (0 < option_edit && launch_editor(git_path_merge_msg(the_repository), NULL, NULL)) {
+		abort_commit(remoteheads, NULL);
 	}

This may reduce the number of lines, but personally I find that

	if (are we editing?) {
		if (run editor---did we fail?)
			abort();
	}

is much easier to read.

And much more importantly, it would be much easier to extend later what hwppens when we decide to edit, than the new code proposed by this patch.

builtin/merge.c static int merging_a_throwaway_tag(struct commit *commit) · line 1215

Quoted 6 lines

builtin/merge.c +1 -1

@@ -1213,7 +1212,7 @@ static int merging_a_throwaway_tag(struct commit *commit)
 	if (!merge_remote_util(commit) ||
 	    !merge_remote_util(commit)->obj ||
 	    merge_remote_util(commit)->obj->type != OBJ_TAG)
-		return is_throwaway_tag;
+		return 0;

Likewise. If somebody _must_ touch this function to gain commit count without making the code harder to maintain, it may be an option to use "goto leave;" here and then create a "leave:" label before the other "return"---at least that may be worth considering, but not this---when everybody else in the function wants to maintain that the value in this variable is what is returned from the function.

Quoted 7 lines

builtin/merge.c +0 -3

@@ -1459,13 +1458,12 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			fast_forward = FF_NO;
 	}
 
-	if (!use_strategies) {
-		if (!remoteheads)
-			; /* already up-to-date */

builtin/merge.c int cmd_merge(int argc, const char **argv, const char *prefix) · line 1467

Quoted 10 lines

builtin/merge.c +5 -3

-		else if (!remoteheads->next)
-			add_strategies(pull_twohead, DEFAULT_TWOHEAD);
-		else
+	if (!use_strategies && remoteheads) {
+		/* not up-to-date */
+		if (remoteheads->next)
 			add_strategies(pull_octopus, DEFAULT_OCTOPUS);
+		else
+			add_strategies(pull_twohead, DEFAULT_TWOHEAD);
 	}

Likewise.

	if (do we have to choose strategies ourselves?) {
		... depending on the case, choose strategy ...
	}

is much easier to reason about than

	if (do we have to choose strategies ourselves?, oh by the
    	    way, don't forget that already up-to-date case we do not
	    have to choose) {
		... the remainder ...
	}

and extend when we need to add something to do in the up-to-date case as long as the end-user did not specify which strategy to use in the future. The reduced line count alone is not a good yardstick to use when talking about code restructuring for readability and maintainability.

Thanks.

Seija K. via GitGitGadget

author

2020-11-17 21:54 UTC #2 lore raw

PATCH v2 1/1 Simplify merge logic

In reply to Seija K. via GitGitGadget

From: Seija K <[email protected]>

commit: Avoid extraneous boolean checking by simplifying the if statements. This is so that the code can be clearer and avoid duplicate boolean checks.

Changes since v1: Undid if statement combos as suggested by Junio C Hamano.

The current logic for the merging is somewhat confusing. So I simplified said logic to be equivalent, but simpler. I tested all my changes to ensure in practice they work as well.

First, I tested out which branch would occur for every possible value below:

remoteheads->next | common->next | option_commit | Branch -- | -- | -- | --

T | T | T | A
T | T | F | A
T | F | T | A
T | F | F | A
F | T | T | C
F | T | F | C
F | F | T | B
F | F | F | A

Then, using this truth table, I was able to deduce that if the second branch ran, the if statement for the first branch would be false.

Then, taking the inverse, I found that many of the checks were redundant, so I rewrote the if statements to have each branch run under the same exact conditions, except each value is evaluated as little as possible.

I hope you find value in these changes.

Thank you!

Signed-off-by Seija K. <[email protected]>

---
Simplify merge logic

This is so that the code can be clearer and avoid duplicate boolean checks.

Changes since v1: Undid if statement combos as suggested by Junio C Hamano.

The current logic for the merging is somewhat confusing. So I simplified said logic to be equivalent, but simpler. I tested all my changes to ensure in practice they work as well.

First, I tested out which branch would occur for every possible value below:

remoteheads->nextcommon->nextoption_commitBranchTTTATTFATFTATFFAFTTCFTFC FFTBFFFAThen, using this truth table, I was able to deduce that if the second branch ran, the if statement for the first branch would be false.

I hope you find value in these changes.

Thank you!

Signed-off-by Seija K. [email protected] [[email protected]]

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-911%2Fpi1024e%2Fmerge-cleanup-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-911/pi1024e/merge-cleanup-v2
Pull-Request: https://github.com/git/git/pull/911

Range-diff vs v1:

1: 9b333c9872 ! 1: dd1c4dd678 Simplified merge logic

     @@
       ## Metadata ##
     -Author: pi1024e <[email protected]>
     +Author: Seija K <[email protected]>
      
       ## Commit message ##
     -    Simplified merge logic
     +    Simplify merge logic
      
          commit: Avoid extraneous boolean checking by simplifying the if statements.
     -    Signed-off-by: Seija <[email protected]>
     +    This is so that the code can be clearer and avoid duplicate boolean checks.
     +
     +    Changes since v1: Undid if statement combos as suggested by Junio C Hamano.
     +
     +    The current logic for the merging is somewhat confusing.
     +    So I simplified said logic to be equivalent, but simpler.
     +    I tested all my changes to ensure in practice they work as well.
     +
     +    First, I tested out which branch would occur for every possible value below:
     +
     +    remoteheads->next | common->next | option_commit | Branch
     +    -- | -- | -- | --
     +    T | T | T | A
     +    T | T | F | A
     +    T | F | T | A
     +    T | F | F | A
     +    F | T | T | C
     +    F | T | F | C
     +    F | F | T | B
     +    F | F | F | A
     +
     +    Then, using this truth table, I was able to deduce that if the second branch ran,
     +    the if statement for the first branch would be false.
     +
     +    Then, taking the inverse, I found that many of the checks were redundant,
     +    so I rewrote the if statements to have each branch run under the same exact conditions,
     +    except each value is evaluated as little as possible.
     +
     +    I hope you find value in these changes.
     +
     +    Thank you!
     +
     +    Signed-off-by: Seija K. <[email protected]>
      
       ## builtin/merge.c ##
     -@@ builtin/merge.c: static void prepare_to_commit(struct commit_list *remoteheads)
     - 	if (run_commit_hook(0 < option_edit, get_index_file(), "prepare-commit-msg",
     - 			    git_path_merge_msg(the_repository), "merge", NULL))
     - 		abort_commit(remoteheads, NULL);
     --	if (0 < option_edit) {
     --		if (launch_editor(git_path_merge_msg(the_repository), NULL, NULL))
     --			abort_commit(remoteheads, NULL);
     -+	if (0 < option_edit && launch_editor(git_path_merge_msg(the_repository), NULL, NULL)) {
     -+		abort_commit(remoteheads, NULL);
     - 	}
     - 
     - 	if (!no_verify && run_commit_hook(0 < option_edit, get_index_file(),
      @@ builtin/merge.c: static int merging_a_throwaway_tag(struct commit *commit)
       	if (!merge_remote_util(commit) ||
       	    !merge_remote_util(commit)->obj ||
     @@ builtin/merge.c: static int merging_a_throwaway_tag(struct commit *commit)
       	/*
       	 * Now we know we are merging a tag object.  Are we downstream
      @@ builtin/merge.c: int cmd_merge(int argc, const char **argv, const char *prefix)
     - 			fast_forward = FF_NO;
       	}
       
     --	if (!use_strategies) {
     + 	if (!use_strategies) {
      -		if (!remoteheads)
      -			; /* already up-to-date */
      -		else if (!remoteheads->next)
      -			add_strategies(pull_twohead, DEFAULT_TWOHEAD);
      -		else
     -+	if (!use_strategies && remoteheads) {
     -+		/* not up-to-date */
     -+		if (remoteheads->next)
     - 			add_strategies(pull_octopus, DEFAULT_OCTOPUS);
     -+		else
     -+			add_strategies(pull_twohead, DEFAULT_TWOHEAD);
     +-			add_strategies(pull_octopus, DEFAULT_OCTOPUS);
     ++		if (remoteheads) {
     ++			/* not up-to-date */
     ++			if (remoteheads->next)
     ++				add_strategies(pull_octopus, DEFAULT_OCTOPUS);
     ++			else
     ++				add_strategies(pull_twohead, DEFAULT_TWOHEAD);
     ++		}
       	}
       
       	for (i = 0; i < use_strategies_nr; i++) {

 builtin/merge.c | 82 +++++++++++++++++++++++--------------------------
 1 file changed, 38 insertions(+), 44 deletions(-)

builtin/merge.c +38 ~~-44~~

index 4c133402a6..148d08f8db 100644
@@ -1213,7 +1213,7 @@ static int merging_a_throwaway_tag(struct commit *commit)
 	if (!merge_remote_util(commit) ||
 	    !merge_remote_util(commit)->obj ||
 	    merge_remote_util(commit)->obj->type != OBJ_TAG)
-		return is_throwaway_tag;
+		return 0;
 
 	/*
 	 * Now we know we are merging a tag object.  Are we downstream

@@ -1460,12 +1460,13 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	}
 
 	if (!use_strategies) {
-		if (!remoteheads)
-			; /* already up-to-date */
-		else if (!remoteheads->next)
-			add_strategies(pull_twohead, DEFAULT_TWOHEAD);
-		else
-			add_strategies(pull_octopus, DEFAULT_OCTOPUS);
+		if (remoteheads) {
+			/* not up-to-date */
+			if (remoteheads->next)
+				add_strategies(pull_octopus, DEFAULT_OCTOPUS);
+			else
+				add_strategies(pull_twohead, DEFAULT_TWOHEAD);
+		}
 	}
 
 	for (i = 0; i < use_strategies_nr; i++) {

@@ -1475,15 +1476,15 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			allow_trivial = 0;
 	}
 
-	if (!remoteheads)
-		; /* already up-to-date */
-	else if (!remoteheads->next)
-		common = get_merge_bases(head_commit, remoteheads->item);
-	else {
-		struct commit_list *list = remoteheads;
-		commit_list_insert(head_commit, &list);
-		common = get_octopus_merge_bases(list);
-		free(list);
+	if (remoteheads) {
+		/* not up-to-date */
+		if (remoteheads->next) {
+			struct commit_list *list = remoteheads;
+			commit_list_insert(head_commit, &list);
+			common = get_octopus_merge_bases(list);
+			free(list);
+		} else
+			common = get_merge_bases(head_commit, remoteheads->item);
 	}
 
 	update_ref("updating ORIG_HEAD", "ORIG_HEAD",

@@ -1542,31 +1543,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		finish(head_commit, remoteheads, &commit->object.oid, msg.buf);
 		remove_merge_branch_state(the_repository);
 		goto done;
-	} else if (!remoteheads->next && common->next)
-		;
-		/*
-		 * We are not doing octopus and not fast-forward.  Need
-		 * a real merge.
-		 */
-	else if (!remoteheads->next && !common->next && option_commit) {
-		/*
-		 * We are not doing octopus, not fast-forward, and have
-		 * only one common.
-		 */
-		refresh_cache(REFRESH_QUIET);
-		if (allow_trivial && fast_forward != FF_ONLY) {
-			/* See if it is really trivial. */
-			git_committer_info(IDENT_STRICT);
-			printf(_("Trying really trivial in-index merge...\n"));
-			if (!read_tree_trivial(&common->item->object.oid,
-					       &head_commit->object.oid,
-					       &remoteheads->item->object.oid)) {
-				ret = merge_trivial(head_commit, remoteheads);
-				goto done;
-			}
-			printf(_("Nope.\n"));
-		}
-	} else {
+	} else if (remoteheads->next || (!common->next && !option_commit)) {
 		/*
 		 * An octopus.  If we can reach all the remote we are up
 		 * to date.

@@ -1592,6 +1569,24 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			finish_up_to_date(_("Already up to date. Yeeah!"));
 			goto done;
 		}
+	} else if (!common->next) {
+		/*
+		 * We are not doing octopus, not fast-forward, and have
+		 * only one common.
+		 */
+		refresh_cache(REFRESH_QUIET);
+		if (allow_trivial && fast_forward != FF_ONLY) {
+			/* See if it is really trivial. */
+			git_committer_info(IDENT_STRICT);
+			printf(_("Trying really trivial in-index merge...\n"));
+			if (!read_tree_trivial(&common->item->object.oid,
+					       &head_commit->object.oid,
+					       &remoteheads->item->object.oid)) {
+				ret = merge_trivial(head_commit, remoteheads);
+				goto done;
+			}
+			printf(_("Nope.\n"));
+		}
 	}
 
 	if (fast_forward == FF_ONLY)

@@ -1685,9 +1680,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 				use_strategies[0]->name);
 		ret = 2;
 		goto done;
-	} else if (best_strategy == wt_strategy)
-		; /* We already have its result in the working tree. */
-	else {
+	} else if (best_strategy != wt_strategy) {
+		/* We do not have its result in the working tree. */
 		printf(_("Rewinding the tree to pristine...\n"));
 		restore_state(&head_commit->object.oid, &stash);
 		printf(_("Using the %s to prepare resolving by hand.\n"),

base-commit: e31aba42fb12bdeb0f850829e008e1e3f43af500

Signature · 1 line

gitgitgadget

Seija K. via GitGitGadget

author

2020-11-17 22:06 UTC #3 lore raw

PATCH v3 1/1 Simplify merge logic

From: Seija K <[email protected]>

commit: Avoid extraneous boolean checking by simplifying the if statements. This is so that the code can be clearer and we can avoid duplicate checks.

Changes since v1: Undid if statement combos as suggested by Junio C Hamano.

Currently, the logic for merging is somewhat confusing. So I simplified said logic to be equivalent, but simpler. I tested all my changes to ensure in practice they work as well.

First, I tested out which branch would occur for every possible value below:

remoteheads->next | common->next | option_commit | Branch -- | -- | -- | --

T | T | T | A
T | T | F | A
T | F | T | A
T | F | F | A
F | T | T | C
F | T | F | C
F | F | T | B
F | F | F | A

Then, using this truth table, I was able to deduce that if the second branch ran, the if statement for the first branch would be false.

I hope you find value in these changes.

Thank you!

Signed-off-by Seija K. <[email protected]>

---
Simplify merge logic

commit: Avoid extraneous boolean checking by simplifying the if statements. This is so that the code can be clearer and we can avoid duplicate checks.

Changes since v1: Undid if statement combos as suggested by Junio C Hamano.

Currently, the logic for merging is somewhat confusing. So I simplified said logic to be equivalent, but simpler. I tested all my changes to ensure in practice they work as well.

First, I tested out which branch would occur for every possible value below:

I hope you find value in these changes.

Thank you!

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-911%2Fpi1024e%2Fmerge-cleanup-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-911/pi1024e/merge-cleanup-v3
Pull-Request: https://github.com/git/git/pull/911

Range-diff vs v2:

1: dd1c4dd678 ! 1: 92e0b7ec32 Simplify merge logic
@@ Commit message
Simplify merge logic

commit: Avoid extraneous boolean checking by simplifying the if statements.
- This is so that the code can be clearer and avoid duplicate boolean checks.
+ This is so that the code can be clearer and we can avoid duplicate checks.

Changes since v1: Undid if statement combos as suggested by Junio C Hamano.

- The current logic for the merging is somewhat confusing.
+ Currently, the logic for merging is somewhat confusing.
So I simplified said logic to be equivalent, but simpler. I tested all my changes to ensure in practice they work as well.

 builtin/merge.c | 82 +++++++++++++++++++++++--------------------------
 1 file changed, 38 insertions(+), 44 deletions(-)

builtin/merge.c +38 ~~-44~~

index 4c133402a6..148d08f8db 100644
@@ -1213,7 +1213,7 @@ static int merging_a_throwaway_tag(struct commit *commit)
 	if (!merge_remote_util(commit) ||
 	    !merge_remote_util(commit)->obj ||
 	    merge_remote_util(commit)->obj->type != OBJ_TAG)
-		return is_throwaway_tag;
+		return 0;
 
 	/*
 	 * Now we know we are merging a tag object.  Are we downstream

@@ -1460,12 +1460,13 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	}
 
 	if (!use_strategies) {
-		if (!remoteheads)
-			; /* already up-to-date */
-		else if (!remoteheads->next)
-			add_strategies(pull_twohead, DEFAULT_TWOHEAD);
-		else
-			add_strategies(pull_octopus, DEFAULT_OCTOPUS);
+		if (remoteheads) {
+			/* not up-to-date */
+			if (remoteheads->next)
+				add_strategies(pull_octopus, DEFAULT_OCTOPUS);
+			else
+				add_strategies(pull_twohead, DEFAULT_TWOHEAD);
+		}
 	}
 
 	for (i = 0; i < use_strategies_nr; i++) {

@@ -1475,15 +1476,15 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			allow_trivial = 0;
 	}
 
-	if (!remoteheads)
-		; /* already up-to-date */
-	else if (!remoteheads->next)
-		common = get_merge_bases(head_commit, remoteheads->item);
-	else {
-		struct commit_list *list = remoteheads;
-		commit_list_insert(head_commit, &list);
-		common = get_octopus_merge_bases(list);
-		free(list);
+	if (remoteheads) {
+		/* not up-to-date */
+		if (remoteheads->next) {
+			struct commit_list *list = remoteheads;
+			commit_list_insert(head_commit, &list);
+			common = get_octopus_merge_bases(list);
+			free(list);
+		} else
+			common = get_merge_bases(head_commit, remoteheads->item);
 	}
 
 	update_ref("updating ORIG_HEAD", "ORIG_HEAD",

@@ -1542,31 +1543,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		finish(head_commit, remoteheads, &commit->object.oid, msg.buf);
 		remove_merge_branch_state(the_repository);
 		goto done;
-	} else if (!remoteheads->next && common->next)
-		;
-		/*
-		 * We are not doing octopus and not fast-forward.  Need
-		 * a real merge.
-		 */
-	else if (!remoteheads->next && !common->next && option_commit) {
-		/*
-		 * We are not doing octopus, not fast-forward, and have
-		 * only one common.
-		 */
-		refresh_cache(REFRESH_QUIET);
-		if (allow_trivial && fast_forward != FF_ONLY) {
-			/* See if it is really trivial. */
-			git_committer_info(IDENT_STRICT);
-			printf(_("Trying really trivial in-index merge...\n"));
-			if (!read_tree_trivial(&common->item->object.oid,
-					       &head_commit->object.oid,
-					       &remoteheads->item->object.oid)) {
-				ret = merge_trivial(head_commit, remoteheads);
-				goto done;
-			}
-			printf(_("Nope.\n"));
-		}
-	} else {
+	} else if (remoteheads->next || (!common->next && !option_commit)) {
 		/*
 		 * An octopus.  If we can reach all the remote we are up
 		 * to date.

@@ -1592,6 +1569,24 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			finish_up_to_date(_("Already up to date. Yeeah!"));
 			goto done;
 		}
+	} else if (!common->next) {
+		/*
+		 * We are not doing octopus, not fast-forward, and have
+		 * only one common.
+		 */
+		refresh_cache(REFRESH_QUIET);
+		if (allow_trivial && fast_forward != FF_ONLY) {
+			/* See if it is really trivial. */
+			git_committer_info(IDENT_STRICT);
+			printf(_("Trying really trivial in-index merge...\n"));
+			if (!read_tree_trivial(&common->item->object.oid,
+					       &head_commit->object.oid,
+					       &remoteheads->item->object.oid)) {
+				ret = merge_trivial(head_commit, remoteheads);
+				goto done;
+			}
+			printf(_("Nope.\n"));
+		}
 	}
 
 	if (fast_forward == FF_ONLY)

@@ -1685,9 +1680,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 				use_strategies[0]->name);
 		ret = 2;
 		goto done;
-	} else if (best_strategy == wt_strategy)
-		; /* We already have its result in the working tree. */
-	else {
+	} else if (best_strategy != wt_strategy) {
+		/* We do not have its result in the working tree. */
 		printf(_("Rewinding the tree to pristine...\n"));
 		restore_state(&head_commit->object.oid, &stash);
 		printf(_("Using the %s to prepare resolving by hand.\n"),

base-commit: e31aba42fb12bdeb0f850829e008e1e3f43af500

Signature · 1 line

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