patchsend-email: clarify missing subject error

6 messages between Aug 9, 2026 and Aug 10, 2026, from Harald Nordgren via GitGitGadget, Junio C Hamano, Harald Nordgren.

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Harald Nordgren via GitGitGadgetAug 9, 2026, 09:23 UTC on lore

From: Harald Nordgren <haraldnordgren@gmail.com>

Explain the required Subject: prefix when a message file has no subject. Terminate the error with a newline so Perl does not append its internal source location.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    send-email: clarify missing subject error
    
    Explain the required Subject: prefix when a message file has no subject.
    Terminate the error with a newline so Perl does not append its internal
    source location.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2375%2FHaraldNordgren%2Ffix%2Fsend-email-subject-error-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2375/HaraldNordgren/fix/send-email-subject-error-v1
Pull-Request: https://github.com/git/git/pull/2375

 git-send-email.perl   |  3 ++-
 t/t9001-send-email.sh | 15 +++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

Show changes to 2 files +17 −1

git-send-email.perl, t/t9001-send-email.sh

diff --git a/git-send-email.perl b/git-send-email.perl
index bb8ddd1eef..4d76d53c49 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -863,7 +863,8 @@ sub get_patch_subject {
 		return "GIT: $1\n";
 	}
 	close $fh;
-	die sprintf(__("No subject line in %s?"), $fn);
+	die sprintf(__("No subject line in %s. " .
+		"The first line must start with \"Subject: \"\n"), $fn);
 }
 
 if ($compose) {
diff --git a/t/t9001-send-email.sh b/t/t9001-send-email.sh
index e9d814a34a..a403dd278b 100755
--- a/t/t9001-send-email.sh
+++ b/t/t9001-send-email.sh
@@ -1422,6 +1422,21 @@ test_expect_success $PREREQ 'detects ambiguous reference/file conflict' '
 	test_grep disambiguate errors
 '
 
+test_expect_success $PREREQ 'missing subject omits Perl location' '
+	cat >no-subject.patch <<-\EOF &&
+	This is the body.
+	EOF
+	test_must_fail git send-email \
+		--dry-run \
+		--from="Example <nobody@example.com>" \
+		--to=nobody@example.com \
+		no-subject.patch 2>actual &&
+	cat >expect <<-\EOF &&
+	No subject line in no-subject.patch. The first line must start with "Subject: "
+	EOF
+	test_cmp expect actual
+'
+
 test_expect_success $PREREQ 'feed two files' '
 	rm -fr outdir &&
 	git format-patch -2 -o outdir &&

base-commit: 010afd3166ddc64c9863b1506f12cbcdda0d4ea1

-- 
gitgitgadget

Junio C HamanoAug 9, 2026, 19:13 UTC in reply to Harald Nordgren via GitGitGadget on lore

Re: [PATCH] send-email: clarify missing subject error

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Harald Nordgren <haraldnordgren@gmail.com>
>
> Explain the required Subject: prefix when a message file has no subject.

Yes, get_patch_subject() is called from places where the caller wants to determine whether the given file has at least one line that begins with 'Subject:'. In that case, the subroutine returns the rest of that line; if it does not find any such line, it issues an error message and dies.

As a side note, the check is curiously case-sensitive. It is also curious that the scanning does not stop at the first blank line that terminates the email headers. However, do not change this behavior without studying the possible ramifications. People have learned to use various inputs that are not exactly what is output by 'git format-patch', so rejecting a 'malformed' file simply because it differs from typical 'git format-patch' output will break someone's established workflow.

> Terminate the error with a newline so Perl does not append its internal
> source location.

Very nice spotting. For an end-user facing script, the source location is not useful. The user is not debugging and fixing the send-email script after all ;-).

Show 12 quoted lines

> diff --git a/git-send-email.perl b/git-send-email.perl
> index bb8ddd1eef..4d76d53c49 100755
> --- a/git-send-email.perl
> +++ b/git-send-email.perl
> @@ -863,7 +863,8 @@ sub get_patch_subject {
>  		return "GIT: $1\n";
>  	}
>  	close $fh;
> -	die sprintf(__("No subject line in %s?"), $fn);
> +	die sprintf(__("No subject line in %s. " .
> +		"The first line must start with \"Subject: \"\n"), $fn);
>  }

An input file to the 'git send-email' program is often the output of 'git format-patch'. Such a file begins with a UNIX 'From ' line, followed by email headers such as 'From:', 'Date:', and 'Subject:'. The 'Subject:' line cannot be the first line of the file in this case, yet it is a valid input.

The only condition that this subroutine flags as an error is when the file lacks a subject line. "No 'Subject:' line in '%s'\n" is a clear message to display and is an improvement over the original.

However, the fact that the first line does not start with "Subject:" is irrelevant to the basis of the subroutine's decision to issue an error, I think.

Thanks.

Harald NordgrenAug 10, 2026, 09:48 UTC in reply to Junio C Hamano on lore

Re: [PATCH] send-email: clarify missing subject error

Show 13 quoted lines

> An input file to the 'git send-email' program is often the output
> of 'git format-patch'.  Such a file begins with a UNIX 'From '
> line, followed by email headers such as 'From:', 'Date:', and
> 'Subject:'.  The 'Subject:' line cannot be the first line of
> the file in this case, yet it is a valid input.
>
> The only condition that this subroutine flags as an error is when
> the file lacks a subject line.  "No 'Subject:' line in '%s'\n" is a
> clear message to display and is an improvement over the original.
>
> However, the fact that the first line does not start with
> "Subject:" is irrelevant to the basis of the subroutine's
> decision to issue an error, I think.

Yeah, that makes sense, so maybe we don't need to focus on it being the first line, but Subject needs to be there somewhere before the body.

Harald

Junio C HamanoAug 10, 2026, 15:28 UTC in reply to Harald Nordgren on lore

Re: [PATCH] send-email: clarify missing subject error

Harald Nordgren <haraldnordgren@gmail.com> writes:

Show 17 quoted lines

>> An input file to the 'git send-email' program is often the output
>> of 'git format-patch'.  Such a file begins with a UNIX 'From '
>> line, followed by email headers such as 'From:', 'Date:', and
>> 'Subject:'.  The 'Subject:' line cannot be the first line of
>> the file in this case, yet it is a valid input.
>>
>> The only condition that this subroutine flags as an error is when
>> the file lacks a subject line.  "No 'Subject:' line in '%s'\n" is a
>> clear message to display and is an improvement over the original.
>>
>> However, the fact that the first line does not start with
>> "Subject:" is irrelevant to the basis of the subroutine's
>> decision to issue an error, I think.
>
> Yeah, that makes sense, so maybe we don't need to focus on it being
> the first line, but Subject needs to be there somewhere before the
> body.

Yeah, the curious thing is that the subroutine with the loop is happy as long as it finds "^Subject: " somewhere, not necessarily before the first blank line.

That is why I said "No 'Subject: ' line in '%s'\n" is clear enough and an improvement over the original. Anything else will add lie to it.

Thanks.

Harald Nordgren via GitGitGadgetAug 10, 2026, 17:53 UTC in reply to Harald Nordgren via GitGitGadget on lore

[PATCH v2] send-email: clarify missing subject error

From: Harald Nordgren <haraldnordgren@gmail.com>

Clarify that a message file is missing a 'Subject:' line.

Terminate the error with a newline so Perl does not append its internal source location.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
---
    send-email: clarify missing subject error
    
    Explain the required Subject: prefix when a message file has no subject.
    Terminate the error with a newline so Perl does not append its internal
    source location.
    
    Changes in v2:
    
     * Remove the incorrect claim that Subject: must be the first line.
       Report the missing header directly as No 'Subject:' line in '<file>'.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2375%2FHaraldNordgren%2Ffix%2Fsend-email-subject-error-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2375/HaraldNordgren/fix/send-email-subject-error-v2
Pull-Request: https://github.com/git/git/pull/2375

Range-diff vs v1:

 1:  fe4171b0dc ! 1:  7002c5d5f1 send-email: clarify missing subject error
     @@ Metadata
       ## Commit message ##
          send-email: clarify missing subject error
      
     -    Explain the required Subject: prefix when a message file has no subject.
     +    Clarify that a message file is missing a 'Subject:' line.
     +
          Terminate the error with a newline so Perl does not append its internal
          source location.
      
     @@ git-send-email.perl: sub get_patch_subject {
       	}
       	close $fh;
      -	die sprintf(__("No subject line in %s?"), $fn);
     -+	die sprintf(__("No subject line in %s. " .
     -+		"The first line must start with \"Subject: \"\n"), $fn);
     ++	die sprintf(__("No 'Subject:' line in '%s'\n"), $fn);
       }
       
       if ($compose) {
     @@ t/t9001-send-email.sh: test_expect_success $PREREQ 'detects ambiguous reference/
      +		--to=nobody@example.com \
      +		no-subject.patch 2>actual &&
      +	cat >expect <<-\EOF &&
     -+	No subject line in no-subject.patch. The first line must start with "Subject: "
     ++	No '\''Subject:'\'' line in '\''no-subject.patch'\''
      +	EOF
      +	test_cmp expect actual
      +'

 git-send-email.perl   |  2 +-
 t/t9001-send-email.sh | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

Show changes to 2 files +16 −1

git-send-email.perl, t/t9001-send-email.sh

diff --git a/git-send-email.perl b/git-send-email.perl
index bb8ddd1eef..2071cff6ae 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -863,7 +863,7 @@ sub get_patch_subject {
 		return "GIT: $1\n";
 	}
 	close $fh;
-	die sprintf(__("No subject line in %s?"), $fn);
+	die sprintf(__("No 'Subject:' line in '%s'\n"), $fn);
 }
 
 if ($compose) {
diff --git a/t/t9001-send-email.sh b/t/t9001-send-email.sh
index e9d814a34a..d1393ef197 100755
--- a/t/t9001-send-email.sh
+++ b/t/t9001-send-email.sh
@@ -1422,6 +1422,21 @@ test_expect_success $PREREQ 'detects ambiguous reference/file conflict' '
 	test_grep disambiguate errors
 '
 
+test_expect_success $PREREQ 'missing subject omits Perl location' '
+	cat >no-subject.patch <<-\EOF &&
+	This is the body.
+	EOF
+	test_must_fail git send-email \
+		--dry-run \
+		--from="Example <nobody@example.com>" \
+		--to=nobody@example.com \
+		no-subject.patch 2>actual &&
+	cat >expect <<-\EOF &&
+	No '\''Subject:'\'' line in '\''no-subject.patch'\''
+	EOF
+	test_cmp expect actual
+'
+
 test_expect_success $PREREQ 'feed two files' '
 	rm -fr outdir &&
 	git format-patch -2 -o outdir &&

base-commit: 010afd3166ddc64c9863b1506f12cbcdda0d4ea1

-- 
gitgitgadget

Junio C HamanoAug 10, 2026, 21:09 UTC in reply to Harald Nordgren via GitGitGadget on lore

Re: [PATCH v2] send-email: clarify missing subject error

"Harald Nordgren via GitGitGadget" <gitgitgadget@gmail.com> writes:

Show 12 quoted lines

> +test_expect_success $PREREQ 'missing subject omits Perl location' '
> +	cat >no-subject.patch <<-\EOF &&
> +	This is the body.
> +	EOF
> +	test_must_fail git send-email \
> +		--dry-run \
> +		--from="Example <nobody@example.com>" \
> +		--to=nobody@example.com \
> +		no-subject.patch 2>actual &&
> +	cat >expect <<-\EOF &&
> +	No '\''Subject:'\'' line in '\''no-subject.patch'\''
> +	EOF

OK. We require the message to exactly be this one (not starting with this substring), which makes sure we are not getting the line numbers from die. Good.

Will queue.  This round looks perfect.  Let's mark it for 'next'.

Thanks.