commit 493d5cbedda8690d17a323d3532acfb1fb1845ad
author David Benjamin <davidben@google.com> Mon Apr 18 17:20:27 2022 -0400
committer Boringssl LUCI CQ <boringssl-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed Apr 20 17:23:50 2022 +0000
tree 131c305ccfd0c318ba0eaf3a4e4da338edad1244
parent edbdc240ecb6a2d5a500b8e2eedfe3e6a2423c0a

Try to require C++14.

Now that we've dropped MSVC 2015, I believe we can rely on C++14 (which
is now seven years old). This switches the build to require C++14. I've
gone ahead and switched code in both public headers and within the
library, but if the public headers are a problem, we can revert those
separately.

C++14 doesn't get us quite as much as C++17, but see if we can get to
C++14 first. Still, std::enable_if_t and the less restricted constexpr
are nice wins.

Update-Note: C++14 is now required to build BoringSSL. If the build
breaks, make sure your compiler is C++14-capable and is not passing
-std=c++11. If this is causing problems for your project, let us know.

Change-Id: If03a88e3f8a11980180781f95b806e7f3c3cb6c3
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/52246
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

include/openssl/span.h

diff --git a/include/openssl/span.h b/include/openssl/span.h
index 38e9a96..67a1a5c 100644
--- a/include/openssl/span.h
+++ b/include/openssl/span.h
@@ -99,12 +99,11 @@
   // 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?
+  // TODO(davidben): Require C++17 support for std::is_convertible_v, etc.
   template <typename C>
-  using EnableIfContainer = typename std::enable_if<
+  using EnableIfContainer = std::enable_if_t<
       std::is_convertible<decltype(std::declval<C>().data()), T *>::value &&
-      std::is_integral<decltype(std::declval<C>().size())>::value>::type;
+      std::is_integral<decltype(std::declval<C>().size())>::value>;
 
  public:
   constexpr Span() : Span(nullptr, 0) {}
@@ -113,14 +112,12 @@
   template <size_t N>
   constexpr Span(T (&array)[N]) : Span(array, N) {}
 
-  template <
-      typename C, typename = EnableIfContainer<C>,
-      typename = typename std::enable_if<std::is_const<T>::value, C>::type>
+  template <typename C, typename = EnableIfContainer<C>,
+            typename = std::enable_if_t<std::is_const<T>::value, C>>
   Span(const C &container) : data_(container.data()), size_(container.size()) {}
 
-  template <
-      typename C, typename = EnableIfContainer<C>,
-      typename = typename std::enable_if<!std::is_const<T>::value, C>::type>
+  template <typename C, typename = EnableIfContainer<C>,
+            typename = std::enable_if_t<!std::is_const<T>::value, C>>
   explicit Span(C &container)
       : data_(container.data()), size_(container.size()) {}