[PATCH v3] [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".

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.
    
    v5:
    https://lore.kernel.org/git/pull.1010.git.1627714877.gitgitgadget@gmail.com/
    
    v5-->v6:
    
     1. Deleted the first patch, which could have made git cherry-pick not
        delete CHERRY_PICK_HEAD when using GIT_CHERRY_PICK_HELP, but both
        Junio and Phillip believe that this design does not need to be
        changed.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1010%2Fadlternative%2Fcherry-pick-help-fix-3-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1010/adlternative/cherry-pick-help-fix-3-v3
Pull-Request: https://github.com/gitgitgadget/git/pull/1010

Range-diff vs v2:

 1:  5d2fd55c580 < -:  ----------- [GSOC] cherry-pick: fix bug when used with GIT_CHERRY_PICK_HELP
 2:  5279bca7a79 ! 1:  701645dde17 [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".
      
     +    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>
     @@ Commit message
          Signed-off-by: ZheNing Hu <adlternative@gmail.com>
      
       ## sequencer.c ##
     -@@ sequencer.c: static void print_advice(struct replay_opts *opts, int show_hint)
     +@@ sequencer.c: static void print_advice(struct repository *r, int show_hint,
     + 	char *msg = getenv("GIT_CHERRY_PICK_HELP");
     + 
       	if (msg) {
     - 		advise("%s\n", msg);
     - 	} else if (show_hint) {
     +-		fprintf(stderr, "%s\n", msg);
     ++		advise("%s\n", msg);
     + 		/*
     + 		 * 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) {
      +			advise(_("Resolve all conflicts manually, mark them as resolved with\n"
     @@ sequencer.c: static void print_advice(struct replay_opts *opts, int show_hint)
      +				 "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>'"));

 sequencer.c                     | 11 +++++++++--
 t/t3507-cherry-pick-conflict.sh | 17 ++++++++++++-----
 2 files changed, 21 insertions(+), 7 deletions(-)