+sub has_no_changes {
+ my $commit = shift;
+
+ my @revs = split / /, command_oneline(
+ qw(rev-list --parents -1 -m), $commit);
+
+ # Commits with no parents, e.g. the start of a partial branch,
+ # have changes by definition.
+ return 1 if (@revs < 2);
+
+ # Commits with multiple parents, e.g a merge, have no changes
+ # by definition.
+ return 0 if (@revs > 2);
+
+ return (command_oneline("rev-parse", "$commit^{tree}") eq
+ command_oneline("rev-parse", "$commit~1^{tree}"));
+}
+
+# The GIT_DIR environment variable is not always set until after the command
+# line arguments are processed, so we can't memoize in a BEGIN block.
+{
+ my $memoized = 0;
+
+ sub memoize_svn_mergeinfo_functions {
+ return if $memoized;
+ $memoized = 1;
+
+ my $cache_path = "$ENV{GIT_DIR}/svn/.caches/";
+ mkpath([$cache_path]) unless -d $cache_path;
+
+ tie my %lookup_svn_merge_cache => 'Memoize::Storable',
+ "$cache_path/lookup_svn_merge.db", 'nstore';
+ memoize 'lookup_svn_merge',
+ SCALAR_CACHE => 'FAULT',
+ LIST_CACHE => ['HASH' => \%lookup_svn_merge_cache],
+ ;
+
+ tie my %check_cherry_pick_cache => 'Memoize::Storable',
+ "$cache_path/check_cherry_pick.db", 'nstore';
+ memoize 'check_cherry_pick',
+ SCALAR_CACHE => 'FAULT',
+ LIST_CACHE => ['HASH' => \%check_cherry_pick_cache],
+ ;
+
+ tie my %has_no_changes_cache => 'Memoize::Storable',
+ "$cache_path/has_no_changes.db", 'nstore';
+ memoize 'has_no_changes',
+ SCALAR_CACHE => ['HASH' => \%has_no_changes_cache],
+ LIST_CACHE => 'FAULT',
+ ;
+ }