Merge branch 'fc/pull-merge-rebase'

When a user does not tell "git pull" to use rebase or merge, the
command gives a loud message telling a user to choose between
rebase or merge but creates a merge anyway, forcing users who would
want to rebase to redo the operation.  Fix an early part of this
problem by tightening the condition to give the message---there is
no reason to stop or force the user to choose between rebase or
merge if the history fast-forwards.

* fc/pull-merge-rebase:
  pull: display default warning only when non-ff
  pull: correct condition to trigger non-ff advice
  pull: get rid of unnecessary global variable
  pull: give the advice for choosing rebase/merge much later
  pull: refactor fast-forward check

builtin/pull.c

@@ -324,7 +324,7 @@ static const char *config_get_ff(void)
  * looks for the value of "pull.rebase". If both configuration keys do not
  * exist, returns REBASE_FALSE.
  */
-static enum rebase_type config_get_rebase(void)
+static enum rebase_type config_get_rebase(int *rebase_unspecified)
 {
 	struct branch *curr_branch = branch_get("HEAD");
 	const char *value;
@@ -344,20 +344,7 @@ static enum rebase_type config_get_rebase(void)
 	if (!git_config_get_value("pull.rebase", &value))
 		return parse_config_rebase("pull.rebase", value, 1);
 
-	if (opt_verbosity >= 0 && !opt_ff) {
+	*rebase_unspecified = 1;
-		advise(_("Pulling without specifying how to reconcile divergent branches is\n"
-			 "discouraged. You can squelch this message by running one of the following\n"
-			 "commands sometime before your next pull:\n"
-			 "\n"
-			 "  git config pull.rebase false  # merge (the default strategy)\n"
-			 "  git config pull.rebase true   # rebase\n"
-			 "  git config pull.ff only       # fast-forward only\n"
-			 "\n"
-			 "You can replace \"git config\" with \"git config --global\" to set a default\n"
-			 "preference for all repositories. You can also pass --rebase, --no-rebase,\n"
-			 "or --ff-only on the command line to override the configured default per\n"
-			 "invocation.\n"));
-	}
 
 	return REBASE_FALSE;
 }
@@ -924,6 +911,36 @@ static int run_rebase(const struct object_id *newbase,
 	return ret;
 }
 
+static int get_can_ff(struct object_id *orig_head, struct object_id *orig_merge_head)
+{
+	int ret;
+	struct commit_list *list = NULL;
+	struct commit *merge_head, *head;
+
+	head = lookup_commit_reference(the_repository, orig_head);
+	commit_list_insert(head, &list);
+	merge_head = lookup_commit_reference(the_repository, orig_merge_head);
+	ret = repo_is_descendant_of(the_repository, merge_head, list);
+	free_commit_list(list);
+	return ret;
+}
+
+static void show_advice_pull_non_ff(void)
+{
+	advise(_("Pulling without specifying how to reconcile divergent branches is\n"
+		 "discouraged. You can squelch this message by running one of the following\n"
+		 "commands sometime before your next pull:\n"
+		 "\n"
+		 "  git config pull.rebase false  # merge (the default strategy)\n"
+		 "  git config pull.rebase true   # rebase\n"
+		 "  git config pull.ff only       # fast-forward only\n"
+		 "\n"
+		 "You can replace \"git config\" with \"git config --global\" to set a default\n"
+		 "preference for all repositories. You can also pass --rebase, --no-rebase,\n"
+		 "or --ff-only on the command line to override the configured default per\n"
+		 "invocation.\n"));
+}
+
 int cmd_pull(int argc, const char **argv, const char *prefix)
 {
 	const char *repo, **refspecs;
@@ -931,6 +948,8 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	struct object_id orig_head, curr_head;
 	struct object_id rebase_fork_point;
 	int autostash;
+	int rebase_unspecified = 0;
+	int can_ff;
 
 	if (!getenv("GIT_REFLOG_ACTION"))
 		set_reflog_message(argc, argv);
@@ -952,7 +971,7 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 		opt_ff = xstrdup_or_null(config_get_ff());
 
 	if (opt_rebase < 0)
-		opt_rebase = config_get_rebase();
+		opt_rebase = config_get_rebase(&rebase_unspecified);
 
 	if (read_cache_unmerged())
 		die_resolve_conflict("pull");
@@ -1026,6 +1045,13 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (opt_rebase && merge_heads.nr > 1)
 		die(_("Cannot rebase onto multiple branches."));
 
+	can_ff = get_can_ff(&orig_head, &merge_heads.oid[0]);
+
+	if (rebase_unspecified && !opt_ff && !can_ff) {
+		if (opt_verbosity >= 0)
+			show_advice_pull_non_ff();
+	}
+
 	if (opt_rebase) {
 		int ret = 0;
 		int ran_ff = 0;
@@ -1040,22 +1066,12 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 		    submodule_touches_in_range(the_repository, &upstream, &curr_head))
 			die(_("cannot rebase with locally recorded submodule modifications"));
 		if (!autostash) {
-			struct commit_list *list = NULL;
+			if (can_ff) {
-			struct commit *merge_head, *head;
-
-			head = lookup_commit_reference(the_repository,
-						       &orig_head);
-			commit_list_insert(head, &list);
-			merge_head = lookup_commit_reference(the_repository,
-							     &merge_heads.oid[0]);
-			if (repo_is_descendant_of(the_repository,
-						  merge_head, list)) {
 				/* we can fast-forward this without invoking rebase */
 				opt_ff = "--ff-only";
 				ran_ff = 1;
 				ret = run_merge();
 			}
-			free_commit_list(list);
 		}
 		if (!ran_ff)
 			ret = run_rebase(&newbase, &upstream);

t/t7601-merge-pull-config.sh

@@ -29,11 +29,8 @@ test_expect_success 'setup' '
 
 test_expect_success 'pull.rebase not set' '
 	git reset --hard c0 &&
-	git -c color.advice=always pull . c1 2>err &&
+	git pull . c1 2>err &&
-	test_decode_color <err >decoded &&
+	test_i18ngrep ! "Pulling without specifying how to reconcile" err
-	test_i18ngrep "<YELLOW>hint: " decoded &&
-	test_i18ngrep "Pulling without specifying how to reconcile" decoded
-
 '
 
 test_expect_success 'pull.rebase not set and pull.ff=true' '
@@ -87,6 +84,65 @@ test_expect_success 'pull.rebase not set and --ff-only given' '
 	test_i18ngrep ! "Pulling without specifying how to reconcile" err
 '
 
+test_expect_success 'pull.rebase not set (not-fast-forward)' '
+	git reset --hard c2 &&
+	git -c color.advice=always pull . c1 2>err &&
+	test_decode_color <err >decoded &&
+	test_i18ngrep "<YELLOW>hint: " decoded &&
+	test_i18ngrep "Pulling without specifying how to reconcile" decoded
+'
+
+test_expect_success 'pull.rebase not set and pull.ff=true (not-fast-forward)' '
+	git reset --hard c2 &&
+	test_config pull.ff true &&
+	git pull . c1 2>err &&
+	test_i18ngrep ! "Pulling without specifying how to reconcile" err
+'
+
+test_expect_success 'pull.rebase not set and pull.ff=false (not-fast-forward)' '
+	git reset --hard c2 &&
+	test_config pull.ff false &&
+	git pull . c1 2>err &&
+	test_i18ngrep ! "Pulling without specifying how to reconcile" err
+'
+
+test_expect_success 'pull.rebase not set and pull.ff=only (not-fast-forward)' '
+	git reset --hard c2 &&
+	test_config pull.ff only &&
+	test_must_fail git pull . c1 2>err &&
+	test_i18ngrep ! "Pulling without specifying how to reconcile" err
+'
+
+test_expect_success 'pull.rebase not set and --rebase given (not-fast-forward)' '
+	git reset --hard c2 &&
+	git pull --rebase . c1 2>err &&
+	test_i18ngrep ! "Pulling without specifying how to reconcile" err
+'
+
+test_expect_success 'pull.rebase not set and --no-rebase given (not-fast-forward)' '
+	git reset --hard c2 &&
+	git pull --no-rebase . c1 2>err &&
+	test_i18ngrep ! "Pulling without specifying how to reconcile" err
+'
+
+test_expect_success 'pull.rebase not set and --ff given (not-fast-forward)' '
+	git reset --hard c2 &&
+	git pull --ff . c1 2>err &&
+	test_i18ngrep ! "Pulling without specifying how to reconcile" err
+'
+
+test_expect_success 'pull.rebase not set and --no-ff given (not-fast-forward)' '
+	git reset --hard c2 &&
+	git pull --no-ff . c1 2>err &&
+	test_i18ngrep ! "Pulling without specifying how to reconcile" err
+'
+
+test_expect_success 'pull.rebase not set and --ff-only given (not-fast-forward)' '
+	git reset --hard c2 &&
+	test_must_fail git pull --ff-only . c1 2>err &&
+	test_i18ngrep ! "Pulling without specifying how to reconcile" err
+'
+
 test_expect_success 'merge c1 with c2' '
 	git reset --hard c1 &&
 	test -f c0.c &&