From 9e6b3783d13f5136c727e6a8247ce2398edc0bb5 Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Mon, 3 Jul 2017 23:52:06 +0300
Subject: Implement workaround for libc++ bug (#33681) in regex_replace_ex()

---
 libbutl/regex.txx | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

(limited to 'libbutl/regex.txx')

diff --git a/libbutl/regex.txx b/libbutl/regex.txx
index 9c6342b..52bddfd 100644
--- a/libbutl/regex.txx
+++ b/libbutl/regex.txx
@@ -3,7 +3,7 @@
 // license   : MIT; see accompanying LICENSE file
 
 #include <locale>
-#include <cstddef> // size_t
+#include <cstddef> // size_t, _LIBCPP_VERSION
 
 namespace butl
 {
@@ -34,10 +34,26 @@ namespace butl
     regex_it e;
     bool match (b != e);
 
+    // For libc++, the end-of-sequence regex iterator can never be reached
+    // for some regular expressions (LLVM bug #33681). We will check if the
+    // matching sequence start is the same as the one for the previous match
+    // and bail out if that's the case.
+    //
+#if defined(_LIBCPP_VERSION) && _LIBCPP_VERSION <= 4000
+    str_it pm;
+#endif
+
     for (regex_it i (b); i != e; ++i)
     {
       const match_results<str_it>& m (*i);
 
+#if defined(_LIBCPP_VERSION) && _LIBCPP_VERSION <= 4000
+      if (i != b && m[0].first == pm)
+        break;
+
+      pm = m[0].first;
+#endif
+
       // Copy the preceeding unmatched substring, save the beginning of the
       // one that follows.
       //
-- 
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