revision: make pseudo-opt flags read via stdin behave consistently

When reading revisions from stdin via git-rev-list(1)'s `--stdin` option
then these revisions never honor flags like `--not` which have been
passed on the command line. Thus, an invocation like e.g. `git rev-list
--all --not --stdin` will not treat all revisions read from stdin as
uninteresting. While this behaviour may be surprising to a user, it's
been this way ever since it has been introduced via 42cabc341c4 (Teach
rev-list an option to read revs from the standard input., 2006-09-05).

With that said, in c40f0b7877 (revision: handle pseudo-opts in `--stdin`
mode, 2023-06-15) we have introduced a new mode to read pseudo opts from
standard input where this behaviour is a lot more confusing. If you pass
`--not` via stdin, it will:

    - Influence subsequent revisions or pseudo-options passed on the
      command line.

    - Influence pseudo-options passed via standard input.

    - _Not_ influence normal revisions passed via standard input.

This behaviour is extremely inconsistent and bound to cause confusion.

While it would be nice to retroactively change the behaviour for how
`--not` and `--stdin` behave together, chances are quite high that this
would break existing scripts that expect the current behaviour that has
been around for many years by now. This is thus not really a viable
option to explore to fix the inconsistency.

Instead, we change the behaviour of how pseudo-opts read via standard
input influence the flags such that the effect is fully localized. With
this change, when reading `--not` via standard input, it will:

    - _Not_ influence subsequent revisions or pseudo-options passed on
      the command line, which is a change in behaviour.

    - Influence pseudo-options passed via standard input.

    - Influence normal revisions passed via standard input, which is a
      change in behaviour.

Thus, all flags read via standard input are fully self-contained to that
standard input, only.

While this is a breaking change as well, the behaviour has only been
recently introduced with Git v2.42.0. Furthermore, the current behaviour
can be regarded as a simple bug. With that in mind it feels like the
right thing to retroactively change it and make the behaviour sane.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Reported-by: Christian Couder <christian.couder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/revision.c b/revision.c
index 2f4c53e..a1f573c 100644
--- a/revision.c
+++ b/revision.c
@@ -2788,13 +2788,13 @@ static int handle_revision_pseudo_opt(struct rev_info *revs,
 }
 
 static void read_revisions_from_stdin(struct rev_info *revs,
-				      struct strvec *prune,
-				      int *flags)
+				      struct strvec *prune)
 {
 	struct strbuf sb;
 	int seen_dashdash = 0;
 	int seen_end_of_options = 0;
 	int save_warning;
+	int flags = 0;
 
 	save_warning = warn_on_object_refname_ambiguity;
 	warn_on_object_refname_ambiguity = 0;
@@ -2817,13 +2817,13 @@ static void read_revisions_from_stdin(struct rev_info *revs,
 				continue;
 			}
 
-			if (handle_revision_pseudo_opt(revs, argv, flags) > 0)
+			if (handle_revision_pseudo_opt(revs, argv, &flags) > 0)
 				continue;
 
 			die(_("invalid option '%s' in --stdin mode"), sb.buf);
 		}
 
-		if (handle_revision_arg(sb.buf, revs, 0,
+		if (handle_revision_arg(sb.buf, revs, flags,
 					REVARG_CANNOT_BE_FILENAME))
 			die("bad revision '%s'", sb.buf);
 	}
@@ -2906,7 +2906,7 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
 				}
 				if (revs->read_from_stdin++)
 					die("--stdin given twice?");
-				read_revisions_from_stdin(revs, &prune_data, &flags);
+				read_revisions_from_stdin(revs, &prune_data);
 				continue;
 			}