Merge branch 'da/user-useconfigonly'

The "user.useConfigOnly" configuration variable can be used to
force the user to always set user.email & user.name configuration
variables, serving as a reminder for those who work on multiple
projects and do not want to put these in their $HOME/.gitconfig.

* da/user-useconfigonly:
  ident: add user.useConfigOnly boolean for when ident shouldn't be guessed
  fmt_ident: refactor strictness checks

Documentation/config.txt

@@ -2830,6 +2830,16 @@ user.name::
 	Can be overridden by the 'GIT_AUTHOR_NAME' and 'GIT_COMMITTER_NAME'
 	environment variables.  See linkgit:git-commit-tree[1].
 
+user.useConfigOnly::
+	Instruct Git to avoid trying to guess defaults for 'user.email'
+	and 'user.name', and instead retrieve the values only from the
+	configuration. 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 will prompt you to set up an email before
+	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

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) "&"
@@ -345,32 +348,40 @@ const char *fmt_ident(const char *name, const char *email,
 	int want_date = !(flag & IDENT_NO_DATE);
 	int want_name = !(flag & IDENT_NO_NAME);
 
-	if (want_name && !name)
-		name = ident_default_name();
-	if (!email)
-		email = ident_default_email();
-
-	if (want_name && !*name) {
-		struct passwd *pw;
-
-		if (strict) {
-			if (name == git_default_name.buf)
+	if (want_name) {
+		int using_default = 0;
+		if (!name) {
+			name = ident_default_name();
+			using_default = 1;
+			if (strict && default_name_is_bogus) {
 				fputs(env_hint, stderr);
-			die("empty ident name (for <%s>) not allowed", email);
+				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;
+			if (strict) {
+				if (using_default)
+					fputs(env_hint, stderr);
+				die("empty ident name (for <%s>) not allowed", email);
+			}
+			pw = xgetpwuid_self(NULL);
+			name = pw->pw_name;
 		}
-		pw = xgetpwuid_self(NULL);
-		name = pw->pw_name;
-	}
-
-	if (want_name && strict &&
-	    name == git_default_name.buf && default_name_is_bogus) {
-		fputs(env_hint, stderr);
-		die("unable to auto-detect name (got '%s')", name);
 	}
 
-	if (strict && email == git_default_email.buf && default_email_is_bogus) {
-		fputs(env_hint, stderr);
-		die("unable to auto-detect email address (got '%s')", email);
+	if (!email) {
+		email = ident_default_email();
+		if (strict && default_email_is_bogus) {
+			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);
@@ -444,6 +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);
@@ -451,6 +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;
 	}
 
@@ -461,6 +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;
 	}
 

t/t7517-per-repo-email.sh

@@ -0,0 +1,39 @@
+#!/bin/sh
+#
+# Copyright (c) 2016 Dan Aloni
+# Copyright (c) 2016 Jeff King
+#
+
+test_description='per-repo forced setting of email address'
+
+. ./test-lib.sh
+
+test_expect_success 'setup a likely user.useConfigOnly use case' '
+	# we want to make sure a reflog is written, since that needs
+	# a non-strict ident. So be sure we have an actual commit.
+	test_commit foo &&
+
+	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
+'
+
+test_expect_success 'fails committing if clone email is not set' '
+	test_must_fail git commit --allow-empty -m msg
+'
+
+test_expect_success 'fails committing if clone email is not set, but EMAIL set' '
+	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_config user.email "test@ok.com" &&
+	git commit --allow-empty -m msg
+'
+
+test_expect_success 'succeeds cloning if global email is not set' '
+	git clone . clone
+'
+
+test_done