grep: show non-empty lines before functions with -Wrs/include-comments-before-the-function-header

Non-empty lines before a function definition are most likely comments
for that function and thus relevant.  Include them in function context.

Such a non-empty line might also belong to the preceding function if
there is no separating blank line.  Stop extending the context upwards
also at the next function line to make sure only one extra function body
is shown at most.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 24 insertions, 5 deletions

diff --git a/grep.c b/grep.c
index 2c55d10c55..a69c05edc2 100644
--- a/grep.c
+++ b/grep.c
@@ -1476,33 +1476,52 @@ static void show_funcname_line(struct grep_opt *opt, struct grep_source *gs,
 	}
 }
 
+static int is_empty_line(const char *bol, const char *eol);
+
 static void show_pre_context(struct grep_opt *opt, struct grep_source *gs,
 			     char *bol, char *end, unsigned lno)
 {
 	unsigned cur = lno, from = 1, funcname_lno = 0, orig_from;
-	int funcname_needed = !!opt->funcname;
+	int funcname_needed = !!opt->funcname, comment_needed = 0;
 
 	if (opt->pre_context < lno)
 		from = lno - opt->pre_context;
 	if (from <= opt->last_shown)
 		from = opt->last_shown + 1;
 	orig_from = from;
-	if (opt->funcbody && !match_funcname(opt, gs, bol, end)) {
-		funcname_needed = 1;
+	if (opt->funcbody) {
+		if (match_funcname(opt, gs, bol, end))
+			comment_needed = 1;
+		else
+			funcname_needed = 1;
 		from = opt->last_shown + 1;
 	}
 
 	/* Rewind. */
 	while (bol > gs->buf && cur > from) {
+		char *next_bol = bol;
 		char *eol = --bol;
 
 		while (bol > gs->buf && bol[-1] != '\n')
 			bol--;
 		cur--;
+		if (comment_needed && (is_empty_line(bol, eol) ||
+				       match_funcname(opt, gs, bol, eol))) {
+			comment_needed = 0;
+			from = orig_from;
+			if (cur < from) {
+				cur++;
+				bol = next_bol;
+				break;
+			}
+		}
 		if (funcname_needed && match_funcname(opt, gs, bol, eol)) {
 			funcname_lno = cur;
 			funcname_needed = 0;
-			from = orig_from;
+			if (opt->funcbody)
+				comment_needed = 1;
+			else
+				from = orig_from;
 		}
 	}
 
diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index 632b905611..c02ca735b9 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -785,7 +785,7 @@ test_expect_success 'grep -W with userdiff' '
 	git grep -W echo >function-context-userdiff-actual
 '
 
-test_expect_failure ' includes preceding comment' '
+test_expect_success ' includes preceding comment' '
 	grep "# Say hello" function-context-userdiff-actual
 '