ident: reword empty ident error message

There's on point in printing the name, since it is by
definition the empty string if we have reached this code
path. Instead, let's be more clear that we are complaining
about the empty name, but still show the email address that
it is attached to (since that may provide some context to
the user).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ident: refactor NO_DATE flag in fmt_ident

As a short-hand, we extract this flag into the local
variable "name_addr_only". It's more accurate to simply
negate this and refer to it as "want_date", which will be
less confusing when we add more NO_* flags.

While we're touching this part of the code, let's move the
call to ident_default_date() only when we are actually going
to use it, not when we have NO_DATE set, or when we get a
date from the environment.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ident: let callers omit name with fmt_indent

Most callers want to see all of "$name <$email> $date", but
a few want only limited parts, omitting the date, or even
the name. We already have IDENT_NO_DATE to handle the date
part, but there's not a good option for getting just the
email. Callers have to done one of:

  1. Call ident_default_email; this does not respect
     environment variables, nor does it promise to trim
     whitespace or other crud from the result.

  2. Call git_{committer,author}_info; this returns the name
     and email, leaving the caller to parse out the wanted
     bits.

This patch adds IDENT_NO_NAME; it stops short of adding
IDENT_NO_EMAIL, as no callers want it (nor are likely to),
and it complicates the error handling of the function.

When no name is requested, the angle brackets (<>) around
the email address are also omitted.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
format-patch: use GIT_COMMITTER_EMAIL in message ids

Before commit 43ae9f4, we generated the tail of a message id
by calling git_committer_info and parsing the email out of
the result. 43ae9f4 changed to use ident_default_email
directly, so we didn't have to bother with parsing. As a
side effect, it meant we no longer used GIT_COMMITTER_EMAIL
at all.

In general, this is probably reasonable behavior. Either the
default email is sane on your system, or you are using
user.email to provide something sane. The exception is if
you rely on GIT_COMMITTER_EMAIL being set all the time to
override the bogus generated email.

This is unlikely to match anybody's real-life setup, but we
do use it in the test environment. And furthermore, it's
what we have always done, and the change in 43ae9f4 was
about cleaning up, not fixing any bug; we should be
conservative and keep the behavior identical.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ident: rename IDENT_ERROR_ON_NO_NAME to IDENT_STRICT

Callers who ask for ERROR_ON_NO_NAME are not so much
concerned that the name will be blank (because, after all,
we will fall back to using the username), but rather it is a
check to make sure that low-quality identities do not end up
in things like commit messages or emails (whereas it is OK
for them to end up in things like reflogs).

When future commits add more quality checks on the identity,
each of these callers would want to use those checks, too.
Rather than modify each of them later to add a new flag,
let's refactor the flag.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ident: reject bogus email addresses with IDENT_STRICT

If we come up with a hostname like "foo.(none)" because the
user's machine is not fully qualified, we should reject this
in strict mode (e.g., when we are making a commit object),
just as we reject an empty gecos username.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
format-patch: do not use bogus email addresses in message ids

We can ask git_committer_info to be strict about coming up
with an email, which will die automatically on a poorly
configured machine. This is better than letting invalid
message-ids into the wild.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>