grep: die gracefully when outside repository

Die gracefully when `git grep --no-index` is run outside of a Git
repository and the path is outside the directory tree.

If you are not in a Git repository and say:

    git grep --no-index search ..

You trigger a `BUG`:

    BUG: environment.c:213: git environment hasn't been setup
    Aborted (core dumped)

Because `..` is a valid path which is treated as a pathspec. Then
`pathspec` figures out that it is not in the current directory tree. The
`BUG` is triggered when `pathspec` tries to advise the user about how the
path is not in the current (non-existing) repository.

Reported-by: ks1322 ks1322 <[email protected]>
Helped-by: Junio C Hamano <[email protected]>
Signed-off-by: Kristoffer Haugsbakk <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: LemmingAvalanche

pathspec.c

@@ -467,7 +467,12 @@ static void init_pathspec_item(struct pathspec_item *item, unsigned flags,
 		match = prefix_path_gently(prefix, prefixlen,
 					   &prefixlen, copyfrom);
 		if (!match) {
-			const char *hint_path = get_git_work_tree();
+			const char *hint_path;
+
+			if (!have_git_dir())
+				die(_("'%s' is outside the directory tree"),
+				    copyfrom);
+			hint_path = get_git_work_tree();
 			if (!hint_path)
 				hint_path = get_git_dir();
 			die(_("%s: '%s' is outside repository at '%s'"), elt,

t/t7810-grep.sh

@@ -1234,6 +1234,33 @@ test_expect_success 'outside of git repository with fallbackToNoIndex' '
 	)
 '
 
+test_expect_success 'no repository with path outside $cwd' '
+	test_when_finished rm -fr non &&
+	rm -fr non &&
+	mkdir -p non/git/sub non/tig &&
+	(
+		GIT_CEILING_DIRECTORIES="$(pwd)/non" &&
+		export GIT_CEILING_DIRECTORIES &&
+		cd non/git &&
+		test_expect_code 128 git grep --no-index search .. 2>error &&
+		grep "is outside the directory tree" error
+	) &&
+	(
+		GIT_CEILING_DIRECTORIES="$(pwd)/non" &&
+		export GIT_CEILING_DIRECTORIES &&
+		cd non/git &&
+		test_expect_code 128 git grep --no-index search ../tig 2>error &&
+		grep "is outside the directory tree" error
+	) &&
+	(
+		GIT_CEILING_DIRECTORIES="$(pwd)/non" &&
+		export GIT_CEILING_DIRECTORIES &&
+		cd non/git &&
+		test_expect_code 128 git grep --no-index search ../non 2>error &&
+		grep "no such path in the working tree" error
+	)
+'
+
 test_expect_success 'inside git repository but with --no-index' '
 	rm -fr is &&
 	mkdir -p is/git/sub &&