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runtime/vm/zone.cc

Index: runtime/vm/zone.cc
diff --git a/runtime/vm/zone.cc b/runtime/vm/zone.cc
index ea42f49055c2d6ce6d447feff7ec3b315a334cc7..7cb7977944dcbbc78dedecf334b15f109fe9c5bb 100644
--- a/runtime/vm/zone.cc
+++ b/runtime/vm/zone.cc
@@ -178,6 +178,21 @@ char* Zone::MakeCopyOfString(const char* str) {
 }
 
 
+char* Zone::ConcatStrings(const char* a, const char* b, char join) {
+  intptr_t a_len = (a == NULL) ? 0 : strlen(a);
+  const intptr_t b_len = strlen(b) + 1;  // '\0'-terminated.
+  const intptr_t len = a_len + b_len;
+  char* copy = Alloc<char>(len);
+  if (a_len > 0) {
+    strncpy(copy, a, a_len);
+    // Insert join character.
+    copy[a_len++] = join;
+  }
+  strncpy(&copy[a_len], b, b_len);
+  return copy;
+}
+
+
 #if defined(DEBUG)
 void Zone::DumpZoneSizes() {
   intptr_t size = 0;