[PATCH] grep: do not do external grep on skip-worktree entries

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

Skip-worktree entries are not on disk. There is no reason to call
external grep in such cases.

A trace message is also added to aid debugging external grep cases.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 builtin-grep.c |   19 ++++++++++++++++++-
 1 files changed, 18 insertions(+), 1 deletions(-)

diff --git a/builtin-grep.c b/builtin-grep.c
index d582232..d49c637 100644
--- a/builtin-grep.c
+++ b/builtin-grep.c
@@ -488,17 +488,34 @@ static int grep_cache(struct grep_opt *opt, const char **paths, int cached,
 	read_cache();
 
 #if !NO_EXTERNAL_GREP
+	if (cached)
+		external_grep_allowed = 0;
+	if (external_grep_allowed) {
+		for (nr = 0; nr < active_nr; nr++) {
+			struct cache_entry *ce = active_cache[nr];
+			if (!S_ISREG(ce->ce_mode))
+				continue;
+			if (!pathspec_matches(paths, ce->name, opt->max_depth))
+				continue;
+			if (ce_skip_worktree(ce)) {
+				external_grep_allowed = 0;
+				break;
+			}
+		}
+	}
 	/*
 	 * Use the external "grep" command for the case where
 	 * we grep through the checked-out files. It tends to
 	 * be a lot more optimized
 	 */
-	if (!cached && external_grep_allowed) {
+	if (external_grep_allowed) {
 		hit = external_grep(opt, paths, cached);
 		if (hit >= 0)
 			return hit;
 		hit = 0;
 	}
+	else
+		trace_printf("grep: external grep not used\n");
 #endif
 
 	for (nr = 0; nr < active_nr; nr++) {
-- 
1.6.6.315.g1a406