commit e6435d8f03f5310b07425d7d0acee7f0b8f52d8c
from: Stefan Sperling <stsp@stsp.name>
date: Sat Oct 17 14:37:41 2020 UTC

search for prototypes above, not at, the first line touched by the diff chunk

commit - 13e2caa3edcc68a62e29b4d5503254cd5bf80b2b
commit + e6435d8f03f5310b07425d7d0acee7f0b8f52d8c
blob - 5101e49206dbcf9bfcd8df71242aec39ed8f57a0
blob + 56fa5047632143a80c4e6c2514162e5a9dc18f88
--- lib/diff_output.c
+++ lib/diff_output.c
@@ -255,12 +255,12 @@ diff_output_match_function_prototype(char **prototype,
 
 	*prototype = NULL;
 
-	if (result->left.atoms.len > 0) {
+	if (result->left.atoms.len > 0 && cc->left.start > 0) {
 		data = &result->left;
-		start_atom = &data->atoms.head[cc->left.start];
-	} else if (result->right.atoms.len > 0) {
+		start_atom = &data->atoms.head[cc->left.start - 1];
+	} else if (result->right.atoms.len > 0 && cc->right.start > 0) {
 		data = &result->right;
-		start_atom = &data->atoms.head[cc->right.start];
+		start_atom = &data->atoms.head[cc->right.start - 1];
 	} else
 		return DIFF_RC_OK;