From 9d4e460b298a39ee2be2443af97413e7063fa8d2 Mon Sep 17 00:00:00 2001
From: Fabian Homborg <FHomborg@gmail.com>
Date: Fri, 4 Jan 2019 08:45:53 +0100
Subject: [PATCH] string: Fix crash with _GLIBCXX_ASSERTIONS

This asserted because we accessed wcstring::front() when it was empty.

Instead, check explicitly for it being empty before.

Fixes #5479
---
 src/builtin_string.cpp | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/builtin_string.cpp b/src/builtin_string.cpp
index 6e810a32..bbc7e40c 100644
--- a/src/builtin_string.cpp
+++ b/src/builtin_string.cpp
@@ -622,9 +622,13 @@ class wildcard_matcher_t : public string_matcher_t {
             }
         }
         if (opts.entire) {
-            // If the pattern is empty, this becomes one ANY_STRING that matches everything.
-            if (wcpattern.front() != ANY_STRING) wcpattern.insert(0, 1, ANY_STRING);
-            if (wcpattern.back() != ANY_STRING) wcpattern.push_back(ANY_STRING);
+            if (!wcpattern.empty()) {
+                if (wcpattern.front() != ANY_STRING) wcpattern.insert(0, 1, ANY_STRING);
+                if (wcpattern.back() != ANY_STRING) wcpattern.push_back(ANY_STRING);
+            } else {
+                // If the pattern is empty, this becomes one ANY_STRING that matches everything.
+                wcpattern.push_back(ANY_STRING);
+            }
         }
     }
 
-- 
2.20.1