[PATCH v4] [GSOC] cherry-pick: use better advice message

From: ZheNing Hu <adlternative@gmail.com>

In the past, git cherry-pick would print such advice when there was a conflict:

hint: after resolving the conflicts, mark the corrected paths hint: with 'git add <paths>' or 'git rm <paths>' hint: and commit the result with 'git commit'

But in fact, when we want to cherry-pick multiple commits, we should not use "git commit" after resolving conflicts, which will make Git generate some errors. We should recommend users to use `git cherry-pick --continue`, `git cherry-pick --abort`, just like git rebase does.

This is the improved advice:

hint: Resolve all conflicts manually, mark them as resolved with hint: "git add/rm <conflicted_files>", then run hint: "git cherry-pick --continue". hint: You can instead skip this commit: run "git cherry-pick --skip". hint: To abort and get back to the state before "git cherry-pick", hint: run "git cherry-pick --abort".

Similarly, this optimization can be applied to git revert:

hint: Resolve all conflicts manually, mark them as resolved with hint: "git add/rm <conflicted_files>", then run hint: "git revert --continue". hint: You can instead skip this commit: run "git revert --skip". hint: To abort and get back to the state before "git revert", hint: run "git revert --abort".

It is worth mentioning that now we use advice() to print the content of GIT_CHERRY_PICK_HELP in print_advice(), each line of output will start with "hint: ".

Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by Hariom Verma <hariom18599@gmail.com>:
Helped-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Hepled-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: ZheNing Hu <adlternative@gmail.com>
---
    [GSOC] cherry-pick: use better advice message
    
    Because git cherry-pick's past advice message is not good enough, it
    often misleads new users of Git, so this patch makes git chery-pick
    advice message better.
    
    v6:
    https://lore.kernel.org/git/pull.1010.v3.git.1628142482640.gitgitgadget@gmail.com/
    
    v6-->v7:
    
     1. Modify the advice order, respect git cherry-pick --no-commit advice.
     2. Let git revert also use better message.
     3. Use double quotes instead of single quotes for the test body.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1010%2Fadlternative%2Fcherry-pick-help-fix-3-v4
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1010/adlternative/cherry-pick-help-fix-3-v4
Pull-Request: https://github.com/gitgitgadget/git/pull/1010

Range-diff vs v3:

 1:  701645dde17 ! 1:  dc51c0b8c2b [GSOC] cherry-pick: use better advice message
     @@ Commit message
          hint: To abort and get back to the state before "git cherry-pick",
          hint: run "git cherry-pick --abort".
      
     +    Similarly, this optimization can be applied to git revert:
     +
     +    hint: Resolve all conflicts manually, mark them as resolved with
     +    hint: "git add/rm <conflicted_files>", then run
     +    hint: "git revert --continue".
     +    hint: You can instead skip this commit: run "git revert --skip".
     +    hint: To abort and get back to the state before "git revert",
     +    hint: run "git revert --abort".
     +
          It is worth mentioning that now we use advice() to print the content
          of GIT_CHERRY_PICK_HELP in print_advice(), each line of output will
          start with "hint: ".
     @@ sequencer.c: static void print_advice(struct repository *r, int show_hint,
       		 * A conflict has occurred but the porcelain
       		 * (typically rebase --interactive) wants to take care
      @@ sequencer.c: static void print_advice(struct repository *r, int show_hint,
     - 	}
     - 
     - 	if (show_hint) {
     --		if (opts->no_commit)
     -+		if (opts->action == REPLAY_PICK) {
     + 		if (opts->no_commit)
     + 			advise(_("after resolving the conflicts, mark the corrected paths\n"
     + 				 "with 'git add <paths>' or 'git rm <paths>'"));
     ++		else if (opts->action == REPLAY_PICK)
      +			advise(_("Resolve all conflicts manually, mark them as resolved with\n"
      +				 "\"git add/rm <conflicted_files>\", then run\n"
      +				 "\"git cherry-pick --continue\".\n"
      +				 "You can instead skip this commit: run \"git cherry-pick --skip\".\n"
      +				 "To abort and get back to the state before \"git cherry-pick\",\n"
      +				 "run \"git cherry-pick --abort\"."));
     -+		} else if (opts->no_commit)
     - 			advise(_("after resolving the conflicts, mark the corrected paths\n"
     - 				 "with 'git add <paths>' or 'git rm <paths>'"));
     ++		else if (opts->action == REPLAY_REVERT)
     ++			advise(_("Resolve all conflicts manually, mark them as resolved with\n"
     ++				 "\"git add/rm <conflicted_files>\", then run\n"
     ++				 "\"git revert --continue\".\n"
     ++				 "You can instead skip this commit: run \"git revert --skip\".\n"
     ++				 "To abort and get back to the state before \"git revert\",\n"
     ++				 "run \"git revert --abort\"."));
       		else
     + 			advise(_("after resolving the conflicts, mark the corrected paths\n"
     + 				 "with 'git add <paths>' or 'git rm <paths>'\n"
     +
     + ## t/t3501-revert-cherry-pick.sh ##
     +@@ t/t3501-revert-cherry-pick.sh: test_expect_success 'cherry-pick works with dirty renamed file' '
     + 	grep -q "^modified$" renamed
     + '
     + 
     ++test_expect_success 'advice from failed revert' '
     ++	echo dream >dream &&
     ++	git add dream &&
     ++	git commit -m "add dream" &&
     ++	dream_oid=$(git rev-parse --short HEAD) &&
     ++	cat <<-EOF >expected &&
     ++	error: could not revert $dream_oid... add dream
     ++	hint: Resolve all conflicts manually, mark them as resolved with
     ++	hint: "git add/rm <conflicted_files>", then run
     ++	hint: "git revert --continue".
     ++	hint: You can instead skip this commit: run "git revert --skip".
     ++	hint: To abort and get back to the state before "git revert",
     ++	hint: run "git revert --abort".
     ++	EOF
     ++	echo dream >>dream &&
     ++	git add dream &&
     ++	git commit -m "double-add dream" &&
     ++	test_must_fail git revert HEAD^ 2>actual &&
     ++	test_cmp expected actual
     ++'
     + test_done
      
       ## t/t3507-cherry-pick-conflict.sh ##
     -@@ t/t3507-cherry-pick-conflict.sh: test_expect_success 'advice from failed cherry-pick' "
     - 	picked=\$(git rev-parse --short picked) &&
     +@@ t/t3507-cherry-pick-conflict.sh: test_expect_success 'failed cherry-pick does not advance HEAD' '
     + 	test "$head" = "$newhead"
     + '
     + 
     +-test_expect_success 'advice from failed cherry-pick' "
     ++test_expect_success 'advice from failed cherry-pick' '
     + 	pristine_detach initial &&
     + 
     +-	picked=\$(git rev-parse --short picked) &&
     ++	picked=$(git rev-parse --short picked) &&
       	cat <<-EOF >expected &&
     - 	error: could not apply \$picked... picked
     +-	error: could not apply \$picked... picked
      -	hint: after resolving the conflicts, mark the corrected paths
      -	hint: with 'git add <paths>' or 'git rm <paths>'
      -	hint: and commit the result with 'git commit'
     ++	error: could not apply $picked... picked
      +	hint: Resolve all conflicts manually, mark them as resolved with
     -+	hint: \"git add/rm <conflicted_files>\", then run
     -+	hint: \"git cherry-pick --continue\".
     -+	hint: You can instead skip this commit: run \"git cherry-pick --skip\".
     -+	hint: To abort and get back to the state before \"git cherry-pick\",
     -+	hint: run \"git cherry-pick --abort\".
     ++	hint: "git add/rm <conflicted_files>", then run
     ++	hint: "git cherry-pick --continue".
     ++	hint: You can instead skip this commit: run "git cherry-pick --skip".
     ++	hint: To abort and get back to the state before "git cherry-pick",
     ++	hint: run "git cherry-pick --abort".
       	EOF
       	test_must_fail git cherry-pick picked 2>actual &&
       
     -@@ t/t3507-cherry-pick-conflict.sh: test_expect_success 'advice from failed cherry-pick --no-commit' "
     - 	picked=\$(git rev-parse --short picked) &&
     - 	cat <<-EOF >expected &&
     - 	error: could not apply \$picked... picked
     --	hint: after resolving the conflicts, mark the corrected paths
     --	hint: with 'git add <paths>' or 'git rm <paths>'
     -+	hint: Resolve all conflicts manually, mark them as resolved with
     -+	hint: \"git add/rm <conflicted_files>\", then run
     -+	hint: \"git cherry-pick --continue\".
     -+	hint: You can instead skip this commit: run \"git cherry-pick --skip\".
     -+	hint: To abort and get back to the state before \"git cherry-pick\",
     -+	hint: run \"git cherry-pick --abort\".
     - 	EOF
     - 	test_must_fail git cherry-pick --no-commit picked 2>actual &&
     + 	test_cmp expected actual
     +-"
     ++'
       
     + test_expect_success 'advice from failed cherry-pick --no-commit' "
     + 	pristine_detach initial &&

 sequencer.c                     | 16 +++++++++++++++-
 t/t3501-revert-cherry-pick.sh   | 20 ++++++++++++++++++++
 t/t3507-cherry-pick-conflict.sh | 17 ++++++++++-------
 3 files changed, 45 insertions(+), 8 deletions(-)