This reverts commit f5bfcc823ba242a46e20fb6f71c9fbf7ebb222fe, which made "git log -m" imply "--patch" by default. The logic was that "-m", which makes diff generation for merges perform a diff against each parent, has no use unless I am viewing the diff, so we could save the user some typing by turning on display of the resulting diff automatically. That wasn't expected to adversely affect scripts because scripts would either be using a command like "git diff-tree" that already emits diffs by default or would be combining -m with a diff generation option such as --name-status. By saving typing for interactive use without adversely affecting scripts in the wild, it would be a pure improvement. The problem is that although diff generation options are only relevant for the displayed diff, a script author can imagine them affecting path limiting. For example, I might run git log -w --format=%H -- README hoping to list commits that edited README, excluding whitespace-only changes. In fact, a whitespace-only change is not TREESAME so the use of -w here has no effect (since we don't apply these diff generation flags to the diff_options struct rev_info::pruning used for this purpose), but the documentation suggests that it should work Suppose you specified foo as the <paths>. We shall call commits that modify foo !TREESAME, and the rest TREESAME. (In a diff filtered for foo, they look different and equal, respectively.) and a script author who has not tested whitespace-only changes wouldn't notice. Similarly, a script author could include git log -m --first-parent --format=%H -- README to filter the first-parent history for commits that modified README. The -m is a no-op but it reflects the script author's intent. For example, until 1e20a407fe2 (stash list: stop passing "-m" to "git log", 2021-05-21), "git stash list" did this. As a result, we can't safely change "-m" to imply "-p" without fear of breaking such scripts. Restore the previous behavior. Noticed because Rust's src/bootstrap/bootstrap.py made use of this same construct: https://github.com/rust-lang/rust/pull/87513. That script has been updated to omit the unnecessary "-m" option, but we can expect other scripts in the wild to have similar expectations. Signed-off-by: Jonathan Nieder <jrnieder@xxxxxxxxx> --- Hi, Joshua Nelson wrote[1]: > Jonathan Nieder wrote: >> What happens if someone wants to build an older version of Rust? > > For what it's worth, almost no one builds old versions of rust from source > except for distros, and distros wouldn't ever set download-ci-llvm = true. So > this shouldn't affect anyone in practice now that we've removed `-m` on master. Thanks. With that out of the way, I started thinking more clearly about the intent behind this use of `-m` and I'm starting to think it wasn't a typo after all. As a result, in terms of >> a. Revert 'diff-merges: let "-m" imply "-p"'. This buys us time to >> make a more targeted change, make the change more gradually in a >> future release, or just stop encouraging use of "-m" in docs. >> >> b. Make "-m" imply "-p", except in some more 'script-ish' >> circumstances (e.g. when using log --format with a format string) >> >> c. Go ahead with the change and advertise it in release notes. now I lean toward (a). How about this patch? Thanks, Jonathan [1] https://lore.kernel.org/git/CAJ+j++Vj1gY93QuKDhDODXOJGXTiFFEzy0Oew+LWD7a5e7iaTA@xxxxxxxxxxxxxx/ Documentation/diff-options.txt | 8 ++++---- diff-merges.c | 1 - t/t4013-diff-various.sh | 4 ++-- 3 files changed, 6 insertions(+), 7 deletions(-) diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt index 0aebe832057..c89d530d3d1 100644 --- a/Documentation/diff-options.txt +++ b/Documentation/diff-options.txt @@ -49,9 +49,10 @@ ifdef::git-log[] --diff-merges=m::: -m::: This option makes diff output for merge commits to be shown in - the default format. The default format could be changed using + the default format. `-m` will produce the output only if `-p` + is given as well. The default format could be changed using `log.diffMerges` configuration parameter, which default value - is `separate`. `-m` implies `-p`. + is `separate`. + --diff-merges=first-parent::: --diff-merges=1::: @@ -61,8 +62,7 @@ ifdef::git-log[] --diff-merges=separate::: This makes merge commits show the full diff with respect to each of the parents. Separate log entry and diff is generated - for each parent. This is the format that `-m` produced - historically. + for each parent. + --diff-merges=combined::: --diff-merges=c::: diff --git a/diff-merges.c b/diff-merges.c index 0dfcaa1b11b..d897fd8a293 100644 --- a/diff-merges.c +++ b/diff-merges.c @@ -107,7 +107,6 @@ int diff_merges_parse_opts(struct rev_info *revs, const char **argv) if (!strcmp(arg, "-m")) { set_to_default(revs); - revs->merges_imply_patch = 1; } else if (!strcmp(arg, "-c")) { set_combined(revs); revs->merges_imply_patch = 1; diff --git a/t/t4013-diff-various.sh b/t/t4013-diff-various.sh index 7fadc985ccc..e561a8e4852 100755 --- a/t/t4013-diff-various.sh +++ b/t/t4013-diff-various.sh @@ -455,8 +455,8 @@ diff-tree --stat --compact-summary initial mode diff-tree -R --stat --compact-summary initial mode EOF -test_expect_success 'log -m matches log -m -p' ' - git log -m -p master >result && +test_expect_success 'log -m matches pure log' ' + git log master >result && process_diffs result >expected && git log -m >result && process_diffs result >actual && -- 2.32.0.605.g8dce9f2422-goog
