[PATCH v7 2/2] ident: add user.useConfigOnly boolean for when ident shouldn't be guessed

[Dan Aloni <alonid@gmail.com>]

It used to be that:

   git config --global user.email "(none)"

was a viable way for people to force themselves to set user.email in
each repository.  This was helpful for people with more than one
email address, targeting different email addresses for different
clones, as it barred git from creating commit unless the user.email
config was set in the per-repo config to the correct email address.

A recent change, 19ce497c (ident: keep a flag for bogus
default_email, 2015-12-10), however declared that an explicitly
configured user.email is not bogus, no matter what its value is, so
this hack no longer works.

Provide the same functionality by adding a new configuration
variable user.useConfigOnly; when this variable is set, the
user must explicitly set user.email configuration.

Signed-off-by: Dan Aloni <alonid@gmail.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Cc: Eric Sunshine <sunshine@sunshineco.com>
---
 Documentation/config.txt  | 10 +++++++++
 ident.c                   | 16 ++++++++++++++
 t/t9904-per-repo-email.sh | 55 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 81 insertions(+)
 create mode 100755 t/t9904-per-repo-email.sh

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 02bcde6bb596..0d168d92fd79 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -2821,6 +2821,16 @@ user.name::
 	Can be overridden by the 'GIT_AUTHOR_NAME' and 'GIT_COMMITTER_NAME'
 	environment variables.  See linkgit:git-commit-tree[1].
 
+user.useConfigOnly::
+	This instructs Git to avoid trying to guess defaults for 'user.email'
+	and 'user.name' other than strictly from config. For example, if
+	you have multiple email addresses and would like to use a different
+	one for each repository, then with this configuration option set
+	to `true` in the global config along with a name, Git would prompt
+	for you for setting up an email upon making new commits in a newly
+	cloned repository.
+	Defaults to `false`.
+
 user.signingKey::
 	If linkgit:git-tag[1] or linkgit:git-commit[1] is not selecting the
 	key you want it to automatically when creating a signed tag or
diff --git a/ident.c b/ident.c
index f3a431f738cc..6e125821f056 100644
--- a/ident.c
+++ b/ident.c
@@ -13,11 +13,14 @@ static struct strbuf git_default_date = STRBUF_INIT;
 static int default_email_is_bogus;
 static int default_name_is_bogus;
 
+static int ident_use_config_only;
+
 #define IDENT_NAME_GIVEN 01
 #define IDENT_MAIL_GIVEN 02
 #define IDENT_ALL_GIVEN (IDENT_NAME_GIVEN|IDENT_MAIL_GIVEN)
 static int committer_ident_explicitly_given;
 static int author_ident_explicitly_given;
+static int ident_config_given;
 
 #ifdef NO_GECOS_IN_PWENT
 #define get_gecos(ignored) "&"
@@ -354,6 +357,9 @@ const char *fmt_ident(const char *name, const char *email,
 				fputs(env_hint, stderr);
 				die("unable to auto-detect name (got '%s')", name);
 			}
+			if (strict && ident_use_config_only
+			    && !(ident_config_given & IDENT_NAME_GIVEN))
+				die("user.useConfigOnly set but no name given");
 		}
 		if (!*name) {
 			struct passwd *pw;
@@ -373,6 +379,9 @@ const char *fmt_ident(const char *name, const char *email,
 			fputs(env_hint, stderr);
 			die("unable to auto-detect email address (got '%s')", email);
 		}
+		if (strict && ident_use_config_only
+		    && !(ident_config_given & IDENT_MAIL_GIVEN))
+			die("user.useConfigOnly set but no mail given");
 	}
 
 	strbuf_reset(&ident);
@@ -446,6 +455,11 @@ int author_ident_sufficiently_given(void)
 
 int git_ident_config(const char *var, const char *value, void *data)
 {
+	if (!strcmp(var, "user.useconfigonly")) {
+		ident_use_config_only = git_config_bool(var, value);
+		return 0;
+	}
+
 	if (!strcmp(var, "user.name")) {
 		if (!value)
 			return config_error_nonbool(var);
@@ -453,6 +467,7 @@ int git_ident_config(const char *var, const char *value, void *data)
 		strbuf_addstr(&git_default_name, value);
 		committer_ident_explicitly_given |= IDENT_NAME_GIVEN;
 		author_ident_explicitly_given |= IDENT_NAME_GIVEN;
+		ident_config_given |= IDENT_NAME_GIVEN;
 		return 0;
 	}
 
@@ -463,6 +478,7 @@ int git_ident_config(const char *var, const char *value, void *data)
 		strbuf_addstr(&git_default_email, value);
 		committer_ident_explicitly_given |= IDENT_MAIL_GIVEN;
 		author_ident_explicitly_given |= IDENT_MAIL_GIVEN;
+		ident_config_given |= IDENT_MAIL_GIVEN;
 		return 0;
 	}
 
diff --git a/t/t9904-per-repo-email.sh b/t/t9904-per-repo-email.sh
new file mode 100755
index 000000000000..f2b33881e46b
--- /dev/null
+++ b/t/t9904-per-repo-email.sh
@@ -0,0 +1,55 @@
+#!/bin/sh
+#
+# Copyright (c) 2016 Dan Aloni
+#
+
+test_description='per-repo forced setting of email address'
+
+. ./test-lib.sh
+
+reprepare () {
+	git reset --hard initial
+}
+
+test_expect_success setup '
+	# Initial repo state
+	echo "Initial" >foo &&
+	git add foo &&
+	git commit -m foo &&
+	git tag initial &&
+
+	# Setup a likely user.useConfigOnly use case
+	sane_unset GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL &&
+	sane_unset GIT_COMMITTER_NAME GIT_COMMITTER_EMAIL &&
+	git config user.name "test" &&
+	git config --global user.useConfigOnly true &&
+
+	reprepare
+'
+
+test_expect_success 'fails committing if clone email is not set' '
+	test_when_finished reprepare &&
+
+	test_must_fail git commit --allow-empty -m msg
+'
+
+test_expect_success 'fails committing if clone email is not set, but EMAIL set' '
+	test_when_finished reprepare &&
+
+	test_must_fail env EMAIL=test@fail.com git commit --allow-empty -m msg
+'
+
+test_expect_success 'succeeds committing if clone email is set' '
+	test_when_finished reprepare &&
+
+	test_config user.email "test@ok.com" &&
+	git commit --allow-empty -m msg
+'
+
+test_expect_success 'succeeds cloning if global email is not set' '
+	test_when_finished reprepare &&
+
+	git clone . clone
+'
+
+test_done
-- 
2.5.0