commit 290625979a9a458ea260c34233f13f3c02688f70
author Tom Stellard <tstellar@redhat.com> Wed Nov 15 00:21:20 2017 +0000
committer Tom Stellard <tstellar@redhat.com> Wed Nov 15 00:21:20 2017 +0000
tree d2013408ef18ac42daf57fef781031f83fd8e34e
parent 396abfea0eb5d32ef0da81c1274f8064018be078

Merging r313776:

------------------------------------------------------------------------
r313776 | marshall | 2017-09-20 10:34:11 -0700 (Wed, 20 Sep 2017) | 1 line

Fix a bit of UB in __independent_bits_engine. Fixes PR#34663
------------------------------------------------------------------------

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/branches/release_50@318236 91177308-0d34-0410-b5e6-96231b3b80d8

include/algorithm

diff --git a/include/algorithm b/include/algorithm
index 4542275..00db6d7 100644
--- a/include/algorithm
+++ b/include/algorithm
@@ -3013,6 +3013,7 @@
 _UIntType
 __independent_bits_engine<_Engine, _UIntType>::__eval(true_type)
 {
+    const size_t _WRt = numeric_limits<result_type>::digits;
     result_type _Sp = 0;
     for (size_t __k = 0; __k < __n0_; ++__k)
     {
@@ -3021,7 +3022,7 @@
         {
             __u = __e_() - _Engine::min();
         } while (__u >= __y0_);
-        if (__w0_ < _WDt)
+        if (__w0_ < _WRt)
             _Sp <<= __w0_;
         else
             _Sp = 0;
@@ -3034,7 +3035,7 @@
         {
             __u = __e_() - _Engine::min();
         } while (__u >= __y1_);
-        if (__w0_ < _WDt - 1)
+        if (__w0_ < _WRt - 1)
             _Sp <<= __w0_ + 1;
         else
             _Sp = 0;