Remove VS 2015 support.

VS 2017 was released in March 2017, five years ago now. This means VS
2015 is now past our support window.

This will make the unmarked and "vs2017" configs in CI/CQ do the same
thing. I'll follow up with a separate CL in infra/config to switch the
test VS 2019 instead.

Update-Note: BoringSSL may no longer build with VS 2015. Consumers
should upgrade to the latest Visual Studio release. VS 2017 or later is
required.

Change-Id: I477759deb95a27efe132de76d9ed103826110df0
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/52085
Reviewed-by: Bob Beck <bbe@google.com>
Reviewed-by: Adam Langley <agl@google.com>

BUILDING.md

@@ -30,12 +30,10 @@ most recent stable version of each tool.
     by CMake, it may be configured explicitly by setting
     `CMAKE_ASM_NASM_COMPILER`.
 
-  * C and C++ compilers with C++11 support are required. On Windows, MSVC 14
-    (Visual Studio 2015) or later with Platform SDK 8.1 or later are supported,
-    but newer versions are recommended. We will drop support for Visual Studio
-    2015 in March 2022, five years after the release of Visual Studio 2017.
-    Recent versions of GCC (6.1+) and Clang should work on non-Windows
-    platforms, and maybe on Windows too.
+  * C and C++ compilers with C++11 support are required. On Windows, MSVC from
+    Visual Studio 2017 or later with Platform SDK 8.1 or later are supported,
+    but newer versions are recommended. Recent versions of GCC (6.1+) and Clang
+    should work on non-Windows platforms, and maybe on Windows too.
 
   * The most recent stable version of [Go](https://golang.org/dl/) is required.
     Note Go is exempt from the five year support window. If not found by CMake,

crypto/abi_self_test.cc

@@ -58,9 +58,10 @@ TEST(ABITest, SanityCheck) {
 #if defined(OPENSSL_WINDOWS)
     // The invalid epilog makes Windows believe the epilog starts later than it
     // actually does. As a result, immediately after the popq, it does not
-    // realize the stack has been unwound and repeats the work.
-    EXPECT_NONFATAL_FAILURE(CHECK_ABI_SEH(abi_test_bad_unwind_epilog),
-                            "unwound past starting frame");
+    // realize the stack has been unwound and repeats the popq. This will result
+    // in reading the wrong return address and fail to unwind. The exact failure
+    // may vary depending on what was on the stack before.
+    EXPECT_NONFATAL_FAILURE(CHECK_ABI_SEH(abi_test_bad_unwind_epilog), "");
     CHECK_ABI_NO_UNWIND(abi_test_bad_unwind_epilog);
 #endif  // OPENSSL_WINDOWS
   }

include/openssl/span.h

@@ -96,6 +96,16 @@ class Span : private internal::SpanBase<const T> {
  private:
   static const size_t npos = static_cast<size_t>(-1);
 
+  // Heuristically test whether C is a container type that can be converted into
+  // a Span by checking for data() and size() member functions.
+  //
+  // TODO(davidben): Require C++14 support and switch to std::enable_if_t.
+  // Perhaps even C++17 now?
+  template <typename C>
+  using EnableIfContainer = typename std::enable_if<
+      std::is_convertible<decltype(std::declval<C>().data()), T *>::value &&
+      std::is_integral<decltype(std::declval<C>().size())>::value>::type;
+
  public:
   constexpr Span() : Span(nullptr, 0) {}
   constexpr Span(T *ptr, size_t len) : data_(ptr), size_(len) {}
@@ -104,27 +114,12 @@ class Span : private internal::SpanBase<const T> {
   constexpr Span(T (&array)[N]) : Span(array, N) {}
 
   template <
-      typename C,
-      // TODO(davidben): Switch everything to std::enable_if_t when we remove
-      // support for MSVC 2015. Although we could write our own enable_if_t and
-      // MSVC 2015 has std::enable_if_t anyway, MSVC 2015's SFINAE
-      // implementation is problematic and does not work below unless we write
-      // the ::type at use.
-      //
-      // TODO(davidben): Move this and the identical copy below into an
-      // EnableIfContainer alias when we drop MSVC 2015 support. MSVC 2015's
-      // SFINAE support cannot handle type aliases.
-      typename = typename std::enable_if<
-          std::is_convertible<decltype(std::declval<C>().data()), T *>::value &&
-          std::is_integral<decltype(std::declval<C>().size())>::value>::type,
+      typename C, typename = EnableIfContainer<C>,
       typename = typename std::enable_if<std::is_const<T>::value, C>::type>
   Span(const C &container) : data_(container.data()), size_(container.size()) {}
 
   template <
-      typename C,
-      typename = typename std::enable_if<
-          std::is_convertible<decltype(std::declval<C>().data()), T *>::value &&
-          std::is_integral<decltype(std::declval<C>().size())>::value>::type,
+      typename C, typename = EnableIfContainer<C>,
       typename = typename std::enable_if<!std::is_const<T>::value, C>::type>
   explicit Span(C &container)
       : data_(container.data()), size_(container.size()) {}

ssl/handshake_server.cc

@@ -418,7 +418,7 @@ static bool is_probably_jdk11_with_tls13(const SSL_CLIENT_HELLO *client_hello) {
   // JDK 11 always sends extensions in a particular order.
   constexpr uint16_t kMaxFragmentLength = 0x0001;
   constexpr uint16_t kStatusRequestV2 = 0x0011;
-  static CONSTEXPR_ARRAY struct {
+  static constexpr struct {
     uint16_t id;
     bool required;
   } kJavaExtensions[] = {

ssl/internal.h

@@ -245,14 +245,6 @@ UniquePtr<T> MakeUnique(Args &&... args) {
   { abort(); }
 #endif
 
-// CONSTEXPR_ARRAY works around a VS 2015 bug where ranged for loops don't work
-// on constexpr arrays.
-#if defined(_MSC_VER) && !defined(__clang__) && _MSC_VER < 1910
-#define CONSTEXPR_ARRAY const
-#else
-#define CONSTEXPR_ARRAY constexpr
-#endif
-
 // Array<T> is an owning array of elements of |T|.
 template <typename T>
 class Array {

ssl/ssl_key_share.cc

@@ -290,7 +290,7 @@ class CECPQ2KeyShare : public SSLKeyShare {
   HRSS_private_key hrss_private_key_;
 };
 
-CONSTEXPR_ARRAY NamedGroup kNamedGroups[] = {
+constexpr NamedGroup kNamedGroups[] = {
     {NID_secp224r1, SSL_CURVE_SECP224R1, "P-224", "secp224r1"},
     {NID_X9_62_prime256v1, SSL_CURVE_SECP256R1, "P-256", "prime256v1"},
     {NID_secp384r1, SSL_CURVE_SECP384R1, "P-384", "secp384r1"},

util/bot/DEPS

@@ -19,7 +19,7 @@ vars = {
   'checkout_sde': False,
   'checkout_nasm': False,
   'checkout_libcxx': False,
-  'vs_version': '2015',
+  'vs_version': '2017',
 
   # Run the following command to see the latest builds in CIPD:
   #  cipd describe PACKAGE_NAME -version latest

util/bot/vs_toolchain.py

@@ -62,9 +62,6 @@ def FindDepotTools():
 def _GetDesiredVsToolchainHashes(version):
   """Load a list of SHA1s corresponding to the toolchains that we want installed
   to build with."""
-  if version == '2015':
-    # Update 3 final with 10.0.15063.468 SDK and no vctip.exe.
-    return ['f53e4598951162bad6330f7a167486c7ae5db1e5']
   if version == '2017':
     # VS 2017 Update 9 (15.9.12) with 10.0.18362 SDK, 10.0.17763 version of
     # Debuggers, and 10.0.17134 version of d3dcompiler_47.dll, with ARM64