Re: [PATCH] Clarify text filter merge conflict reduction docs
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Jun 29, 2010, 16:19 UTC
- Message-ID
- <7vk4phbyl5.fsf@alter.siamese.dyndns.org>
- In-Reply-To
- <0cd82ad22a6f240ebcde0c2f3a437a805dae5668.1277753114.git.eyvind.bernhardsen@gmail.com>
Eyvind Bernhardsen <eyvind.bernhardsen@gmail.com> writes:
> Signed-off-by: Eyvind Bernhardsen <eyvind.bernhardsen@gmail.com> > --- > How does this look?
Looks Ok (I didn't read _this_ patch but read a squashed-in result), thanks.
> +If you have added attributes to a file that cause... > +...To prevent these unnecessary merge conflicts,
This naturally calls for an optimization idea, doesn't it?
I wonder if ll_merge should gain another flag bit to disable the calls to normalize_file(), so that the whole thing can be skipped when the caller somehow knows .gitattributes files that govern the path didn't change.
That won't be a trivial optimization and my gut feeling is that it shouldn't be part of this series.
I do however wonder if this should be initially introduced as an experimental feature, guarded with a configuration option for brave souls to try it out, and flip the feature on by default after we gain confidence in it, both in performance and in correctness.
-- >8 -- Introduce "double conversion during merge" more gradually
This marks the recent improvement to the merge machinery that helps people who changed their mind between CRLF/LF an opt in feature, so that we can more easily release it early to everybody, without fear of breaking the majority of users (read: on POSIX) that don't need it.
Signed-off-by: Junio C Hamano <gitster@pobox.com> --- Documentation/config.txt | 10 ++++++++++ Documentation/gitattributes.txt | 5 +++-- cache.h | 1 + config.c | 5 +++++ environment.c | 1 + ll-merge.c | 8 +++++--- 6 files changed, 25 insertions(+), 5 deletions(-)
diff --git a/Documentation/config.txt b/Documentation/config.txt index 4c49104..ad2a27e 100644 --- a/Documentation/config.txt +++ b/Documentation/config.txt @@ -538,6 +538,16 @@ core.sparseCheckout:: Enable "sparse checkout" feature. See section "Sparse checkout" in linkgit:git-read-tree[1] for more information. +core.doubleConvert:: + Tell git that canonical representation of files in the repository + has changed over time (e.g. earlier commits record text files + with CRLF line endings, but recent ones use LF line endings). In + such a repository, git is forced to convert the data recorded in + commits twice before performing a merge to reduce unnecessary + conflicts. For more information, see section + "Merging branches with differing checkin/checkout attributes" in + linkgit:gitattributes[5]. + add.ignore-errors:: Tells 'git add' to continue adding files when some files cannot be added due to indexing errors. Equivalent to the '--ignore-errors' diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt index 22400c1..504d5ca 100644 --- a/Documentation/gitattributes.txt +++ b/Documentation/gitattributes.txt @@ -351,9 +351,10 @@ clean/smudge filter or text/eol/ident attributes, merging anything where the attribute is not in place would normally cause merge conflicts. -To prevent these unnecessary merge conflicts, git runs a virtual +To prevent these unnecessary merge conflicts, git can be told to run a virtual check-out and check-in of all three stages of a file when resolving a -three-way merge. This prevents changes caused by check-in conversion +three-way merge by setting `core.doubleConvert` configuration variable. +This prevents changes caused by check-in conversion from causing spurious merge conflicts when a converted file is merged with an unconverted file. diff --git a/cache.h b/cache.h index aa725b0..217f1e9 100644 --- a/cache.h +++ b/cache.h @@ -551,6 +551,7 @@ extern int read_replace_refs; extern int fsync_object_files; extern int core_preload_index; extern int core_apply_sparse_checkout; +extern int core_ll_merge_double_convert; enum safe_crlf { SAFE_CRLF_FALSE = 0, diff --git a/config.c b/config.c index cdcf583..bea054c 100644 --- a/config.c +++ b/config.c @@ -595,6 +595,11 @@ static int git_default_core_config(const char *var, const char *value) return 0; } + if (!strcmp(var, "core.doubleconvert")) { + core_ll_merge_double_convert = git_config_bool(var, value); + return 0; + } + /* Add other config variables here and to Documentation/config.txt. */ return 0; } diff --git a/environment.c b/environment.c index 83d38d3..a8f04e7 100644 --- a/environment.c +++ b/environment.c @@ -53,6 +53,7 @@ enum object_creation_mode object_creation_mode = OBJECT_CREATION_MODE; char *notes_ref_name; int grafts_replace_parents = 1; int core_apply_sparse_checkout; +int core_ll_merge_double_convert; /* Parallel index stat data preload? */ int core_preload_index = 0; diff --git a/ll-merge.c b/ll-merge.c index 28c6f54..8831631 100644 --- a/ll-merge.c +++ b/ll-merge.c @@ -344,9 +344,11 @@ int ll_merge(mmbuffer_t *result_buf, const struct ll_merge_driver *driver; int virtual_ancestor = flag & 01; - normalize_file(ancestor, path); - normalize_file(ours, path); - normalize_file(theirs, path); + if (core_ll_merge_double_convert) { + normalize_file(ancestor, path); + normalize_file(ours, path); + normalize_file(theirs, path); + } if (!git_path_check_merge(path, check)) { ll_driver_name = check[0].value; if (check[1].value) {