[GSoC][PATCH v2] grep: fix worktree case in submodules

[Matheus Tavares <matheus.bernardino@usp.br>]

Running git-grep with --recurse-submodules results in a cached grep for
the submodules even when --cached is not used. This makes all
modifications in submodules' tracked files be always ignored when
grepping. Solve that making git-grep respect the cached option when
invoking grep_cache() inside grep_submodule(). Also, add tests to
ensure that the desired behavior is performed.

Reported-by: Daniel Zaoui <jackdanielz@eyomi.org>
Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
---
Changes in v2:
- repositioned the '/* ignored */' comment to avoid ambiguity
- joined `git clean` and `git reset` invokations in a single `git
  submodule foreach`. 

travis build: https://travis-ci.org/matheustavares/git/builds/565749070

builtin/grep.c                     | 10 ++++++----
 t/t7814-grep-recurse-submodules.sh | 20 ++++++++++++++++++++
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/builtin/grep.c b/builtin/grep.c
index 560051784e..d9866dd936 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -403,7 +403,7 @@ static int grep_tree(struct grep_opt *opt, const struct pathspec *pathspec,
 static int grep_submodule(struct grep_opt *opt,
 			  const struct pathspec *pathspec,
 			  const struct object_id *oid,
-			  const char *filename, const char *path)
+			  const char *filename, const char *path, int cached)
 {
 	struct repository subrepo;
 	struct repository *superproject = opt->repo;
@@ -475,7 +475,7 @@ static int grep_submodule(struct grep_opt *opt,
 		strbuf_release(&base);
 		free(data);
 	} else {
-		hit = grep_cache(&subopt, pathspec, 1);
+		hit = grep_cache(&subopt, pathspec, cached);
 	}
 
 	repo_clear(&subrepo);
@@ -523,7 +523,8 @@ static int grep_cache(struct grep_opt *opt,
 			}
 		} else if (recurse_submodules && S_ISGITLINK(ce->ce_mode) &&
 			   submodule_path_match(repo->index, pathspec, name.buf, NULL)) {
-			hit |= grep_submodule(opt, pathspec, NULL, ce->name, ce->name);
+			hit |= grep_submodule(opt, pathspec, NULL, ce->name,
+					      ce->name, cached);
 		} else {
 			continue;
 		}
@@ -598,7 +599,8 @@ static int grep_tree(struct grep_opt *opt, const struct pathspec *pathspec,
 			free(data);
 		} else if (recurse_submodules && S_ISGITLINK(entry.mode)) {
 			hit |= grep_submodule(opt, pathspec, &entry.oid,
-					      base->buf, base->buf + tn_len);
+					      base->buf, base->buf + tn_len,
+					      1 /* ignored */);
 		}
 
 		strbuf_setlen(base, old_baselen);
diff --git a/t/t7814-grep-recurse-submodules.sh b/t/t7814-grep-recurse-submodules.sh
index a11366b4ce..edb64690e6 100755
--- a/t/t7814-grep-recurse-submodules.sh
+++ b/t/t7814-grep-recurse-submodules.sh
@@ -408,4 +408,24 @@ test_expect_success 'grep --recurse-submodules with submodules without .gitmodul
 	test_cmp expect actual
 '
 
+reset_and_clean () {
+	git reset --hard &&
+	git clean -fd &&
+	git submodule foreach --recursive 'git reset --hard && git clean -fd'
+}
+
+test_expect_success 'grep --recurse-submodules without --cached considers worktree modifications' '
+	reset_and_clean &&
+	echo "A modified line in submodule" >>submodule/a &&
+	echo "submodule/a:A modified line in submodule" >expect &&
+	git grep --recurse-submodules "A modified line in submodule" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'grep --recurse-submodules with --cached ignores worktree modifications' '
+	reset_and_clean &&
+	echo "A modified line in submodule" >>submodule/a &&
+	test_must_fail git grep --recurse-submodules --cached "A modified line in submodule" >actual 2>&1 &&
+	test_must_be_empty actual
+'
 test_done
-- 
2.22.0