[PATCH] D50967: [Preamble] Fix an undefined behavior when checking an empty preamble can be reused.

[Haojian Wu via Phabricator via cfe-commits]

hokein updated this revision to Diff 161891.
hokein added a comment.

Use the std::equal to replace the memcmp.


Repository:
  rC Clang

https://reviews.llvm.org/D50967

Files:
  lib/Frontend/PrecompiledPreamble.cpp


Index: lib/Frontend/PrecompiledPreamble.cpp
===================================================================
--- lib/Frontend/PrecompiledPreamble.cpp
+++ lib/Frontend/PrecompiledPreamble.cpp
@@ -426,8 +426,8 @@
   // new main file.
   if (PreambleBytes.size() != Bounds.Size ||
       PreambleEndsAtStartOfLine != Bounds.PreambleEndsAtStartOfLine ||
-      memcmp(PreambleBytes.data(), MainFileBuffer->getBufferStart(),
-             Bounds.Size) != 0)
+      !std::equal(PreambleBytes.begin(), PreambleBytes.end(),
+                  MainFileBuffer->getBuffer().begin()))
     return false;
   // The preamble has not changed. We may be able to re-use the precompiled
   // preamble.


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