fix-cxx-standard.patch

diff --git a/CMake/abslConfig.cmake.in b/CMake/abslConfig.cmake.in
index 62d246d..00947cf 100644
--- a/CMake/abslConfig.cmake.in
+++ b/CMake/abslConfig.cmake.in
@@ -6,3 +6,5 @@ find_dependency(Threads)
 @PACKAGE_INIT@
 
 include ("${CMAKE_CURRENT_LIST_DIR}/@PROJECT_NAME@Targets.cmake")
+
+set(ABSL_USE_CXX17 @ABSL_USE_CXX17@)
\ No newline at end of file
diff --git a/CMakeLists.txt b/CMakeLists.txt
index f0af6f6..927f4ed 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -57,6 +57,23 @@ else()
   option(ABSL_ENABLE_INSTALL "Enable install rule" ON)
 endif()
 
+# CXX standard
+option(ABSL_USE_CXX17 "Enable CXX 17 standard" OFF)
+
+if (ABSL_USE_CXX17)
+    set(CMAKE_CXX_STANDARD 17)
+    set(STD_ANY 1)
+    set(STD_OPTIONAL 1)
+    set(STD_STRING_VIEW 1)
+    set(STD_VARIANT 1)
+else()
+    set(CMAKE_CXX_STANDARD 11)
+    set(STD_ANY 0)
+    set(STD_OPTIONAL 0)
+    set(STD_STRING_VIEW 0)
+    set(STD_VARIANT 0)
+endif()
+
 list(APPEND CMAKE_MODULE_PATH
   ${CMAKE_CURRENT_LIST_DIR}/CMake
   ${CMAKE_CURRENT_LIST_DIR}/absl/copts
diff --git a/absl/base/CMakeLists.txt b/absl/base/CMakeLists.txt
index 9ff5aa2..315bee4 100644
--- a/absl/base/CMakeLists.txt
+++ b/absl/base/CMakeLists.txt
@@ -87,6 +87,12 @@ absl_cc_library(
     absl::errno_saver
 )
 
+if (NOT EXISTS ${CMAKE_CURRENT_LIST_DIR}/options.h.in)
+    file(RENAME ${CMAKE_CURRENT_LIST_DIR}/options.h ${CMAKE_CURRENT_LIST_DIR}/options.h.in)
+endif()
+file(REMOVE ${CMAKE_CURRENT_LIST_DIR}/options.h)
+configure_file(${CMAKE_CURRENT_LIST_DIR}/options.h.in ${CMAKE_CURRENT_LIST_DIR}/options.h @ONLY)
+
 absl_cc_library(
   NAME
     config
diff --git a/absl/base/options.h b/absl/base/options.h
index 6a0fb07..54a9780 100644
--- a/absl/base/options.h
+++ b/absl/base/options.h
@@ -100,7 +100,7 @@
 // User code should not inspect this macro.  To check in the preprocessor if
 // absl::any is a typedef of std::any, use the feature macro ABSL_USES_STD_ANY.
 
-#define ABSL_OPTION_USE_STD_ANY 2
+#define ABSL_OPTION_USE_STD_ANY @STD_ANY@
 
 
 // ABSL_OPTION_USE_STD_OPTIONAL
@@ -127,7 +127,7 @@
 // absl::optional is a typedef of std::optional, use the feature macro
 // ABSL_USES_STD_OPTIONAL.
 
-#define ABSL_OPTION_USE_STD_OPTIONAL 2
+#define ABSL_OPTION_USE_STD_OPTIONAL @STD_OPTIONAL@
 
 
 // ABSL_OPTION_USE_STD_STRING_VIEW
@@ -154,7 +154,7 @@
 // absl::string_view is a typedef of std::string_view, use the feature macro
 // ABSL_USES_STD_STRING_VIEW.
 
-#define ABSL_OPTION_USE_STD_STRING_VIEW 2
+#define ABSL_OPTION_USE_STD_STRING_VIEW @STD_STRING_VIEW@
 
 // ABSL_OPTION_USE_STD_VARIANT
 //
@@ -180,7 +180,7 @@
 // absl::variant is a typedef of std::variant, use the feature macro
 // ABSL_USES_STD_VARIANT.
 
-#define ABSL_OPTION_USE_STD_VARIANT 2
+#define ABSL_OPTION_USE_STD_VARIANT @STD_VARIANT@
 
 
 // ABSL_OPTION_USE_INLINE_NAMESPACE