Thread (6 messages) 6 messages, 3 authors, 2023-11-13

Re: [PATCH] format-patch: fix ignored encode_email_headers for cover letter

From: Jeff King <hidden>
Date: 2023-11-09 18:35:10

On Thu, Nov 09, 2023 at 11:19:56AM +0000, Simon Ser wrote:
When writing the cover letter, the encode_email_headers option was
ignored. That is, UTF-8 subject lines and email addresses were
written out as-is, without any Q-encoding, even if
--encode-email-headers was passed on the command line.

This is due to encode_email_headers not being copied over from
struct rev_info to struct pretty_print_context. Fix that and add
a test.
That makes sense, and your patch looks the right thing to do as an
immediate fix. But I have to wonder:

  1. Are there other bits that need to be copied? Grepping for other
     code that does the same thing, I see that show_log() and
     cmd_format_patch() copy a lot more. (For that matter, why doesn't
     make_cover_letter() just use the context set up by
     cmd_format_patch()?).

  2. Why are we copying this stuff at all? When we introduced the
     pretty-print context back in 6bf139440c (clean up calling
     conventions for pretty.c functions, 2011-05-26), the idea was just
     to keep all of the format options together. But later, 6d167fd7cc
     (pretty: use fmt_output_email_subject(), 2017-03-01) added a
     pointer to the rev_info directly. So could/should we just be using
     pp->rev->encode_email_headers here?

     Or if that field is not always set (or we want to override some
     elements), should there be a single helper function to initialize
     the pretty_print_context from a rev_info, that could be shared
     between spots like show_log() and make_cover_letter()?

I don't think that answering those questions needs to hold up your
patch. We can take it as a quick fix for a real bug, and then anybody
interested can dig further as a separate topic on top.
quoted hunk ↗ jump to hunk
diff --git a/builtin/log.c b/builtin/log.c
index ba775d7b5cf8..87fd1c8560de 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -1364,6 +1364,7 @@ static void make_cover_letter(struct rev_info *rev, int use_separate_file,
 	pp.date_mode.type = DATE_RFC2822;
 	pp.rev = rev;
 	pp.print_email_subject = 1;
+	pp.encode_email_headers = rev->encode_email_headers;
 	pp_user_info(&pp, NULL, &sb, committer, encoding);
 	prepare_cover_text(&pp, description_file, branch_name, &sb,
 			   encoding, need_8bit_cte);
This part looks obviously good.
+test_expect_success 'cover letter with --cover-from-description subject (UTF-8 subject line)' '
+	test_config branch.rebuild-1.description "Café?
+
+body" &&
+	git checkout rebuild-1 &&
+	git format-patch --stdout --cover-letter --cover-from-description subject --encode-email-headers main >actual &&
+	grep "^Subject: \[PATCH 0/2\] =?UTF-8?q?Caf=C3=A9=3F?=$" actual &&
+	! grep "Café" actual
+'
The test looks correct to me.

Some of these long lines (and the in-string newlines!) make this ugly
and hard to read. But it is also just copying the already-ugly style of
nearby tests. So I'm OK with that. But a prettier version might be:

  test_expect_success 'cover letter respects --encode-email-headers' '
        test_config branch.rebuild-1.description "Café?" &&
        git checkout rebuild-1 &&
        git format-patch --stdout --encode-email-headers \
                --cover-letter --cover-from-description=subject \
                main >actual &&
        ...
  '

I also wondered if we could be just be testing this much more easily
with another header like "--to". But I guess that would be found in both
the cover letter and the actual patches (we also don't seem to encode
it even in the regular patches; is that a bug?).

-Peff
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