From: Christopher Dykes <cdykes@fb.com>
Date: Wed, 3 Aug 2016 22:09:04 +0000 (-0700)
Subject: Force the overflow in BitVectorCoding::skipTo to be 64-bit
X-Git-Tag: v2016.08.08.00~27
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=abb963a06d6f2b7f6d39bbe34c5b6d581d79480e;p=folly.git

Force the overflow in BitVectorCoding::skipTo to be 64-bit

Summary: This code was relying on the `- 1` overflowing as a 64-bit value, but MSVC (correctly in my opinion) was overflowing this as a 32-bit value, resulting in a segfault when trying to run the bitvector and eliasfano tests on MSVC.

Reviewed By: yfeldblum

Differential Revision: D3652343

fbshipit-source-id: 38a22abfc0d05ab2f070c450eebfa69af07d26af
---

diff --git a/folly/experimental/BitVectorCoding.h b/folly/experimental/BitVectorCoding.h
index d51b7b96..a7f711c2 100644
--- a/folly/experimental/BitVectorCoding.h
+++ b/folly/experimental/BitVectorCoding.h
@@ -346,8 +346,8 @@ class BitVectorReader {
 
     if (Encoder::skipQuantum > 0 && v - value_ > Encoder::skipQuantum) {
       size_t q = v / Encoder::skipQuantum;
-      position_ = folly::loadUnaligned<SkipValueType>(
-                      skipPointers_ + (q - 1) * sizeof(SkipValueType)) - 1;
+      position_ = size_t(folly::loadUnaligned<SkipValueType>(
+                      skipPointers_ + (q - 1) * sizeof(SkipValueType))) - 1;
 
       reposition(q * Encoder::skipQuantum);
     }