Have cant_happen() give more information.

1 files changed, 1 insertions, 1 deletions

diff --git a/re.c b/re.c
index fd134727..1caa57e9 100644
--- a/re.c
+++ b/re.c
@@ -144,7 +144,7 @@ make_regexp(const char *s, size_t len, bool ignorecase, bool dfa, bool canfatal)
 			case '7':
 				c2 = parse_escape(&src);
 				if (c2 < 0)
-					cant_happen();
+					cant_happen("received bad result %d from parse_escape()", c2);
 				/*
 				 * Unix awk treats octal (and hex?) chars
 				 * literally in re's, so escape regexp