Subject: Re: [RFC] send-email: UTF-8 encoding in subject line

From: Shreyansh Paliwal <[email-masked]>
Date: Sun, 22 Feb 2026 19:33:52 +0530

> > That makes sense, I tried it below.
> > I also wondered whether, in addition to this, it might be helpful to warn on
> > an invalid charset, and/or possibly fall back to UTF-8.
>
> Agreed on the first half of the statement, if we have an easy and
> portable way to tell if a given random string names a valid charset.
> I do not recommend to "fall back" to anything, if we are asking an
> input from the user.

Following up on this, I tried adding a warning when the provided charset
does not appear to be valid. Current flow is,

  Which 8bit encoding should I declare [UTF-8]? y
  Are you sure you want to use <y> [y/N]? y

With the additional check, it becomes,

  Which 8bit encoding should I declare [default: UTF-8]? y
  warning: 'y' does not appear to be a valid charset name.
  Are you sure you want to use <y> [y/N]?

This uses find_encoding() from Perl’s Encode module to detect any
unrecognized charset names.

Let me know what you think.
Also, is there any new test that should be added for this change?

Signed-off-by: Shreyansh Paliwal <[email-masked]>
---
 git-send-email.perl | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/git-send-email.perl b/git-send-email.perl
index cd4b316ddc..e62fa259ba 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -23,6 +23,7 @@
 use Git::LoadCPAN::Error qw(:try);
 use Git;
 use Git::I18N;
+use Encode qw(find_encoding);
 
 Getopt::Long::Configure qw/ pass_through /;
 
@@ -1044,9 +1045,25 @@ sub file_declares_8bit_cte {
 	foreach my $f (sort keys %broken_encoding) {
 		print "    $f\n";
 	}
-	$auto_8bit_encoding = ask(__("Which 8bit encoding should I declare [UTF-8]? "),
-				  valid_re => qr/.{4}/, confirm_only => 1,
-				  default => "UTF-8");
+	while (1) {
+		my $encoding = ask(__("Which 8bit encoding should I declare [default: UTF-8]? "),
+			valid_re => qr/^\S+$/,
+			default  => "UTF-8");
+		next unless defined $encoding;
+		if (find_encoding($encoding)) {
+			$auto_8bit_encoding = $encoding;
+			last;
+		}
+		printf STDERR __("warning: '%s' does not appear to be a valid charset name.\n"), $encoding;
+		my $yesno = ask(
+			sprintf(__("Are you sure you want to use <%s> [y/N]? "), $encoding),
+			valid_re => qr/^(?:y|n)/i,
+			default  => 'n');
+		if (defined $yesno && $yesno =~ /^y/i) {
+			$auto_8bit_encoding = $encoding;
+			last;
+		}
+	}
 }
 
 if (!$force) {
-- 
2.53.0