vcpkg/ports/google-cloud-cpp/support_absl_cxx17.patch

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a0d07d1..18320b6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -43,6 +43,14 @@ if (APPLE AND NOT DEFINED CMAKE_CXX_STANDARD)
     set(CMAKE_CXX_STANDARD 14)
 endif ()
 
+find_package(absl CONFIG REQUIRED)
+
+# Use CMAKE_CXX_STANDARD=17 if ABSL_USE_CXX17 is set
+if (ABSL_USE_CXX17)
+    message(STATUS "Found absl uses CXX17, enable CXX17 feature.")
+    set(CMAKE_CXX_STANDARD 17)
+endif ()
+
 if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
     if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 7.3)
         message(
diff --git a/google/cloud/internal/port_platform.h b/google/cloud/internal/port_platform.h
index b61eb48..327278f 100644
--- a/google/cloud/internal/port_platform.h
+++ b/google/cloud/internal/port_platform.h
@@ -49,6 +49,8 @@
 // Abort compilation if the compiler does not support C++14.
 #if GOOGLE_CLOUD_CPP_CPP_VERSION < 201402L
 #  error "C++14 or newer is required"
+#elif defined(ABSL_USE_CXX17) && GOOGLE_CLOUD_CPP_CPP_VERSION < 201703L
+#  error "Compiled to use Abseil with C++17 support, but using with C++ < C++17"
 #endif  // GOOGLE_CLOUD_CPP_CPP_VERSION < 201402L
 
 // Abort the build if the version of the compiler is too old. This simplifies