From 8fa9dd51a4602b965d16b970611e04538e08967d Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sat, 9 Jun 2018 13:08:51 +0100
Subject: git-debrebase: Fix snagging

* Rename $snags_checked to $snags_summarised and make it a counter
  of the snags we have summarised in snags_maybe_bail.
* Introduce all_snags_summarised, which uses arithmetic to see if
  we have had new snags since the most recent snags_maybe_bail,
* Use this in run_deferred_updates rather than the existing
  approach; this means we can crash if there were new snags for
  which we should have bailed.
* Make snags_maybe_bail not produce a redundant identical summary.
* Initialise counters to 0 so arithmetic does not give undef warnings.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 git-debrebase | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

(limited to 'git-debrebase')

diff --git a/git-debrebase b/git-debrebase
index d174fe6..d9ceb20 100755
--- a/git-debrebase
+++ b/git-debrebase
@@ -102,17 +102,19 @@ sub fresh_workarea () {
     in_workarea sub { playtree_setup };
 }
 
-our $snags_forced;
-our $snags_tripped;
-our $snags_checked;
+our $snags_forced = 0;
+our $snags_tripped = 0;
+our $snags_summarised = 0;
 our @deferred_updates;
 our @deferred_update_messages;
 
+sub all_snags_summarised () {
+    $snags_forced + $snags_tripped == $snags_summarised;
+}
 sub run_deferred_updates ($) {
     my ($mrest) = @_;
 
-    confess 'dangerous internal error' if
-	!$snags_checked || $snags_tripped || $snags_forced;
+    confess 'dangerous internal error' unless all_snags_summarised();
 
     my @upd_cmd = (@git, qw(update-ref --stdin -m), "debrebase: $mrest");
     debugcmd '>|', @upd_cmd;
@@ -247,26 +249,30 @@ sub snag ($$) {
     }
 }
 
+# Important: all mainline code must call snags_maybe_bail after
+# any point where snag might be called, but before making changes
+# (eg before any call to run_deferred_updates).  snags_maybe_bail
+# may be called more than once if necessary (but this is not ideal
+# because then the messages about number of snags may be confusing).
 sub snags_maybe_bail () {
-    $snags_checked++;
+    return if all_snags_summarised();
     if ($snags_forced) {
 	printf STDERR
 	    "%s: snags: %d overriden by individual -f options\n",
 	    $us, $snags_forced;
-	$snags_forced=0;
     }
     if ($snags_tripped) {
 	if ($opt_force) {
 	    printf STDERR
 		"%s: snags: %d overriden by global --force\n",
 		$us, $snags_tripped;
-	    $snags_tripped=0;
 	} else {
 	    fail sprintf
   "%s: snags: %d blockers (you could -f<tag>, or --force)",
 		$us, $snags_tripped;
 	}
     }
+    $snags_summarised = $snags_forced + $snags_tripped;
 }
 sub any_snags () {
     return $snags_forced || $snags_tripped;
-- 
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