[llvm] ceb9379 - [ADT] Fix join_impl using the wrong size when calculating total length

[Nathan James via llvm-commits]

Author: Nathan James
Date: 2021-01-13T11:36:49Z
New Revision: ceb9379a90f5a320d19f5694ef00b4d1164fa7d6

URL: https://github.com/llvm/llvm-project/commit/ceb9379a90f5a320d19f5694ef00b4d1164fa7d6
DIFF: https://github.com/llvm/llvm-project/commit/ceb9379a90f5a320d19f5694ef00b4d1164fa7d6.diff

LOG: [ADT] Fix join_impl using the wrong size when calculating total length

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D83305

Added: 
    

Modified: 
    llvm/include/llvm/ADT/StringExtras.h

Removed: 
    


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diff  --git a/llvm/include/llvm/ADT/StringExtras.h b/llvm/include/llvm/ADT/StringExtras.h
index 1fea700efe0c..0178539bc402 100644
--- a/llvm/include/llvm/ADT/StringExtras.h
+++ b/llvm/include/llvm/ADT/StringExtras.h
@@ -384,13 +384,16 @@ inline std::string join_impl(IteratorT Begin, IteratorT End,
 
   size_t Len = (std::distance(Begin, End) - 1) * Separator.size();
   for (IteratorT I = Begin; I != End; ++I)
-    Len += (*Begin).size();
+    Len += I->size();
   S.reserve(Len);
+  size_t PrevCapacity = S.capacity();
+  (void)PrevCapacity;
   S += (*Begin);
   while (++Begin != End) {
     S += Separator;
     S += (*Begin);
   }
+  assert(PrevCapacity == S.capacity() && "String grew during building");
   return S;
 }