[PATCH 3/3] builtin/grep: allow implicit --no-index

[Thomas Gummerer <t.gummerer@gmail.com>]

Currently when git grep is used outside of a git repository without the
--no-index option git simply dies.  For convenience, implicitly make git
grep behave like git grep --no-index when it is called outside of a git
repository.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
---
 builtin/grep.c  | 32 ++++++++++++++++++++++++--------
 t/t7810-grep.sh | 41 ++++++++++++++++++++++++++++++++++++++---
 2 files changed, 62 insertions(+), 11 deletions(-)

diff --git a/builtin/grep.c b/builtin/grep.c
index 3a27bd5..a886af1 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -19,6 +19,9 @@
 #include "dir.h"
 #include "pathspec.h"
 
+#define GREP_NO_INDEX_EXPLICIT 1
+#define GREP_NO_INDEX_IMPLICIT 2
+
 static char const * const grep_usage[] = {
 	N_("git grep [<options>] [-e] <pattern> [<rev>...] [[--] <path>...]"),
 	NULL
@@ -632,7 +635,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		OPT_BOOL(0, "cached", &cached,
 			N_("search in index instead of in the work tree")),
 		OPT_BIT(0, "no-index", &no_index,
-			N_("find in contents not managed by git"), 1),
+			N_("find in contents not managed by git"),
+			GREP_NO_INDEX_EXPLICIT),
 		OPT_BOOL(0, "untracked", &untracked,
 			N_("search in both tracked and untracked files")),
 		OPT_SET_INT(0, "exclude-standard", &opt_exclude,
@@ -755,9 +759,13 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 			     PARSE_OPT_STOP_AT_NON_OPTION);
 	grep_commit_pattern_type(pattern_type_arg, &opt);
 
-	if (!no_index && !startup_info->have_repository)
-		/* die the same way as if we did it at the beginning */
-		setup_git_directory();
+	if (!no_index && !startup_info->have_repository) {
+		int nongit = 0;
+
+		setup_git_directory_gently(&nongit);
+		if (nongit)
+			no_index = GREP_NO_INDEX_IMPLICIT;
+	}
 
 	/*
 	 * skip a -- separator; we know it cannot be
@@ -873,13 +881,21 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 	if (!show_in_pager && !opt.status_only)
 		setup_pager();
 
-	if (no_index && (untracked || cached))
-		die(_("--cached or --untracked cannot be used with --no-index."));
+	if (untracked || cached) {
+		if (no_index == GREP_NO_INDEX_EXPLICIT)
+			die(_("--cached or --untracked cannot be used with --no-index."));
+		else if (no_index == GREP_NO_INDEX_IMPLICIT)
+			die(_("--cached or --untracked cannot be used outside a git repository."));
+	}
 
 	if (no_index || untracked) {
 		int use_exclude = (opt_exclude < 0) ? !no_index : !!opt_exclude;
-		if (list.nr)
-			die(_("--no-index or --untracked cannot be used with revs."));
+		if (list.nr) {
+			if (no_index == GREP_NO_INDEX_IMPLICIT)
+				die(_("cannot use revs outside of a git repository."));
+			else
+				die(_("--no-index or --untracked cannot be used with revs."));
+		}
 		hit = grep_directory(&opt, &pathspec, use_exclude);
 	} else if (0 <= opt_exclude) {
 		die(_("--[no-]exclude-standard cannot be used for tracked contents."));
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index ab94716..4ba955d 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -794,11 +794,9 @@ test_expect_success 'outside of git repository' '
 		GIT_CEILING_DIRECTORIES="$(pwd)/non" &&
 		export GIT_CEILING_DIRECTORIES &&
 		cd non/git &&
-		test_must_fail git grep o &&
 		git grep --no-index o >../actual.full &&
 		test_cmp ../expect.full ../actual.full
 		cd sub &&
-		test_must_fail git grep o &&
 		git grep --no-index o >../../actual.sub &&
 		test_cmp ../../expect.sub ../../actual.sub
 	) &&
@@ -808,7 +806,6 @@ test_expect_success 'outside of git repository' '
 		GIT_CEILING_DIRECTORIES="$(pwd)/non" &&
 		export GIT_CEILING_DIRECTORIES &&
 		cd non/git &&
-		test_must_fail git grep o &&
 		git grep --no-index --exclude-standard o >../actual.full &&
 		test_cmp ../expect.full ../actual.full &&
 
@@ -821,6 +818,44 @@ test_expect_success 'outside of git repository' '
 	)
 '
 
+test_expect_success 'outside of git repository without --no-index' '
+	rm -fr non &&
+	mkdir -p non/git/sub &&
+	echo hello >non/git/file1 &&
+	echo world >non/git/sub/file2 &&
+	{
+		echo file1:hello &&
+		echo sub/file2:world
+	} >non/expect.full &&
+	echo file2:world >non/expect.sub &&
+	(
+		GIT_CEILING_DIRECTORIES="$(pwd)/non" &&
+		export GIT_CEILING_DIRECTORIES &&
+		cd non/git &&
+		git grep o >../actual.full &&
+		test_cmp ../expect.full ../actual.full
+		cd sub &&
+		git grep o >../../actual.sub &&
+		test_cmp ../../expect.sub ../../actual.sub
+	) &&
+
+	echo ".*o*" >non/git/.gitignore &&
+	(
+		GIT_CEILING_DIRECTORIES="$(pwd)/non" &&
+		export GIT_CEILING_DIRECTORIES &&
+		cd non/git &&
+		git grep --exclude-standard o >../actual.full &&
+		test_cmp ../expect.full ../actual.full &&
+
+		{
+			echo ".gitignore:.*o*"
+			cat ../expect.full
+		} >../expect.with.ignored &&
+		git grep --no-exclude o >../actual.full &&
+		test_cmp ../expect.with.ignored ../actual.full
+	)
+'
+
 test_expect_success 'inside git repository but with --no-index' '
 	rm -fr is &&
 	mkdir -p is/git/sub &&
-- 
2.6.3.387.g749a69c.dirty