grep: fix worktree case in submodules

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>

builtin/grep.c

@@ -400,10 +400,14 @@ static int grep_tree(struct grep_opt *opt, const struct pathspec *pathspec,
 		     struct tree_desc *tree, struct strbuf *base, int tn_len,
 		     int check_attr);
 
+/*
+ * The cached bit is only meaningful when a NULL oid is given (i.e. when not
+ * grepping inside a tree object).
+ */
 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 +479,7 @@ 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 +527,8 @@ 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 +603,7 @@ 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);
 		}
 
 		strbuf_setlen(base, old_baselen);

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