VS 2019 16.8 Preview 3 toolset update (microsoft#1290)

* VSO-1035737 has been fixed.

* Update toolset to VS 2019 16.8 Preview 3.

README.md

@@ -143,7 +143,7 @@ Just try to follow these rules, so we can spend more time fixing bugs and implem
 The STL uses boost-math headers to provide P0226R1 Mathematical Special Functions. We recommend using [vcpkg][] to
 acquire this dependency.
 
-1. Install Visual Studio 2019 16.8 Preview 2 or later.
+1. Install Visual Studio 2019 16.8 Preview 3 or later.
     * We recommend selecting "C++ CMake tools for Windows" in the VS Installer.
     This will ensure that you're using supported versions of CMake and Ninja.
     * Otherwise, install [CMake][] 3.17 or later, and [Ninja][] 1.8.2 or later.
@@ -158,7 +158,7 @@ acquire this dependency.
 
 # How To Build With A Native Tools Command Prompt
 
-1. Install Visual Studio 2019 16.8 Preview 2 or later.
+1. Install Visual Studio 2019 16.8 Preview 3 or later.
     * We recommend selecting "C++ CMake tools for Windows" in the VS Installer.
     This will ensure that you're using supported versions of CMake and Ninja.
     * Otherwise, install [CMake][] 3.17 or later, and [Ninja][] 1.8.2 or later.

azure-pipelines.yml

@@ -4,7 +4,7 @@
 # Build STL targeting x86, x64, arm, arm64
 
 variables:
-  agentPool: 'StlBuild-2020-08-26'
+  agentPool: 'StlBuild-2020-09-14'
   tmpDir: 'D:\Temp'
 
 stages:

tests/libcxx/expected_results.txt

@@ -489,9 +489,6 @@ std/thread/futures/futures.task/futures.task.members/make_ready_at_thread_exit.p
 # Compiler bug: DevCom-409222 "Constructing rvalue reference from non-reference-related lvalue reference"
 std/utilities/meta/meta.unary/meta.unary.prop/is_constructible.pass.cpp:0 FAIL
 
-# Compiler bug: VSO-1035737 "constexpr pointers-by-reference"
-std/iterators/predef.iterators/move.iterators/move.iter.ops/move.iter.op.index/difference_type.pass.cpp:0 FAIL
-
 # Compiler bug: DevCom-876860 "conditional operator errors" blocks readable<volatile int*>.
 std/containers/views/span.cons/ptr_len.pass.cpp:0 FAIL
 std/containers/views/span.cons/ptr_ptr.pass.cpp:0 FAIL

tests/libcxx/skipped_tests.txt

@@ -489,9 +489,6 @@ thread\futures\futures.task\futures.task.members\make_ready_at_thread_exit.pass.
 # Compiler bug: DevCom-409222 "Constructing rvalue reference from non-reference-related lvalue reference"
 utilities\meta\meta.unary\meta.unary.prop\is_constructible.pass.cpp
 
-# Compiler bug: VSO-1035737 "constexpr pointers-by-reference"
-iterators\predef.iterators\move.iterators\move.iter.ops\move.iter.op.index\difference_type.pass.cpp
-
 # Compiler bug: DevCom-876860 "conditional operator errors" blocks readable<volatile int*>.
 containers\views\span.cons\ptr_len.pass.cpp
 containers\views\span.cons\ptr_ptr.pass.cpp