Require C++17

Policy information:
https://opensource.google/documentation/policies/cplusplus-support#c_language_standard
https://github.com/google/oss-policies-info/blob/main/foundational-cxx-support-matrix.md

PiperOrigin-RevId: 723589409
Change-Id: Ia8665c052ed40f2a78308f7eb0c330191b0cf981

Author: derekmauro

CMake/AbseilDll.cmake

@@ -731,10 +731,8 @@ int main() { return 0; }
 
 if(ABSL_INTERNAL_AT_LEAST_CXX20)
   set(ABSL_INTERNAL_CXX_STD_FEATURE cxx_std_20)
-elseif(ABSL_INTERNAL_AT_LEAST_CXX17)
-  set(ABSL_INTERNAL_CXX_STD_FEATURE cxx_std_17)
 else()
-  set(ABSL_INTERNAL_CXX_STD_FEATURE cxx_std_14)
+  set(ABSL_INTERNAL_CXX_STD_FEATURE cxx_std_17)
 endif()
 
 function(absl_internal_dll_contains)
@@ -899,7 +897,7 @@ Cflags: -I\${includedir}${PC_CFLAGS}\n")
   )
 
   if(ABSL_PROPAGATE_CXX_STD)
-    # Abseil libraries require C++14 as the current minimum standard. When
+    # Abseil libraries require C++17 as the current minimum standard. When
     # compiled with a higher minimum (either because it is the compiler's
     # default or explicitly requested), then Abseil requires that standard.
     target_compile_features(${_dll} PUBLIC ${ABSL_INTERNAL_CXX_STD_FEATURE})

CMake/AbseilHelpers.cmake

@@ -301,7 +301,7 @@ Cflags: -I\${includedir}${PC_CFLAGS}\n")
     endif()
 
     if(ABSL_PROPAGATE_CXX_STD)
-      # Abseil libraries require C++14 as the current minimum standard. When
+      # Abseil libraries require C++17 as the current minimum standard. When
       # compiled with a higher standard (either because it is the compiler's
       # default or explicitly requested), then Abseil requires that standard.
       target_compile_features(${_NAME} PUBLIC ${ABSL_INTERNAL_CXX_STD_FEATURE})
@@ -338,7 +338,7 @@ Cflags: -I\${includedir}${PC_CFLAGS}\n")
     target_compile_definitions(${_NAME} INTERFACE ${ABSL_CC_LIB_DEFINES})
 
     if(ABSL_PROPAGATE_CXX_STD)
-      # Abseil libraries require C++14 as the current minimum standard.
+      # Abseil libraries require C++17 as the current minimum standard.
       # Top-level application CMake projects should ensure a consistent C++
       # standard for all compiled sources by setting CMAKE_CXX_STANDARD.
       target_compile_features(${_NAME} INTERFACE ${ABSL_INTERNAL_CXX_STD_FEATURE})
@@ -450,7 +450,7 @@ function(absl_cc_test)
   set_property(TARGET ${_NAME} PROPERTY FOLDER ${ABSL_IDE_FOLDER}/test)
 
   if(ABSL_PROPAGATE_CXX_STD)
-    # Abseil libraries require C++14 as the current minimum standard.
+    # Abseil libraries require C++17 as the current minimum standard.
     # Top-level application CMake projects should ensure a consistent C++
     # standard for all compiled sources by setting CMAKE_CXX_STANDARD.
     target_compile_features(${_NAME} PUBLIC ${ABSL_INTERNAL_CXX_STD_FEATURE})

CMake/README.md

@@ -43,8 +43,8 @@ cmake_minimum_required(VERSION 3.16)
 project(my_app_project)
 
 # Pick the C++ standard to compile with.
-# Abseil currently supports C++14, C++17, and C++20.
-set(CMAKE_CXX_STANDARD 14)
+# Abseil currently supports C++17 and C++20.
+set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 add_subdirectory(abseil-cpp)

CMakeLists.txt

@@ -46,7 +46,7 @@ set(CMAKE_INSTALL_RPATH_USE_LINK_PATH ON)
 set(CMAKE_BUILD_RPATH_USE_ORIGIN ON)
 
 option(ABSL_PROPAGATE_CXX_STD
-  "Use CMake C++ standard meta features (e.g. cxx_std_14) that propagate to targets that link to Abseil"
+  "Use CMake C++ standard meta features (e.g. cxx_std_17) that propagate to targets that link to Abseil"
   ON)
 
 option(ABSL_USE_SYSTEM_INCLUDES

README.md

@@ -1,7 +1,7 @@
 # Abseil - C++ Common Libraries
 
 The repository contains the Abseil C++ library code. Abseil is an open-source
-collection of C++ code (compliant to C++14) designed to augment the C++
+collection of C++ code (compliant to C++17) designed to augment the C++
 standard library.
 
 ## Table of Contents
@@ -99,8 +99,8 @@ Abseil contains the following C++ library components:
   <br /> The `memory` library contains memory management facilities that augment
   C++'s `<memory>` library.
 * [`meta`](absl/meta/)
-  <br /> The `meta` library contains compatible versions of type checks
-  available within C++14 and C++17 versions of the C++ `<type_traits>` library.
+  <br /> The `meta` library contains type checks
+  similar to those available in the C++ `<type_traits>` library.
 * [`numeric`](absl/numeric/)
   <br /> The `numeric` library contains 128-bit integer types as well as
   implementations of C++20's bitwise math functions.
@@ -115,8 +115,7 @@ Abseil contains the following C++ library components:
   specifically `absl::Status` and `absl::StatusOr<T>`.
 * [`strings`](absl/strings/)
   <br /> The `strings` library contains a variety of strings routines and
-  utilities, including a C++14-compatible version of the C++17
-  `std::string_view` type.
+  utilities.
 * [`synchronization`](absl/synchronization/)
   <br /> The `synchronization` library contains concurrency primitives (Abseil's
   `absl::Mutex` class, an alternative to `std::mutex`) and a variety of
@@ -126,8 +125,7 @@ Abseil contains the following C++ library components:
   points in time, durations of time, and formatting and parsing time within
   time zones.
 * [`types`](absl/types/)
-  <br /> The `types` library contains non-container utility types, like a
-  C++14-compatible version of the C++17 `std::optional` type.
+  <br /> The `types` library contains non-container utility types.
 * [`utility`](absl/utility/)
   <br /> The `utility` library contains utility and helper code.
 

absl/base/policy_checks.h

@@ -71,15 +71,15 @@
 // C++ Version Check
 // -----------------------------------------------------------------------------
 
-// Enforce C++14 as the minimum.
+// Enforce C++17 as the minimum.
 #if defined(_MSVC_LANG)
-#if _MSVC_LANG < 201402L
-#error "C++ versions less than C++14 are not supported."
-#endif  // _MSVC_LANG < 201402L
+#if _MSVC_LANG < 201703L
+#error "C++ versions less than C++17 are not supported."
+#endif  // _MSVC_LANG < 201703L
 #elif defined(__cplusplus)
-#if __cplusplus < 201402L
-#error "C++ versions less than C++14 are not supported."
-#endif  // __cplusplus < 201402L
+#if __cplusplus < 201703L
+#error "C++ versions less than C++17 are not supported."
+#endif  // __cplusplus < 201703L
 #endif
 
 // -----------------------------------------------------------------------------

ci/linux_arm_clang-latest_libcxx_bazel.sh

@@ -25,7 +25,7 @@ if [[ -z ${ABSEIL_ROOT:-} ]]; then
 fi
 
 if [[ -z ${STD:-} ]]; then
-  STD="c++14 c++17 c++20"
+  STD="c++17 c++20"
 fi
 
 if [[ -z ${COMPILATION_MODE:-} ]]; then

ci/linux_clang-latest_libcxx_asan_bazel.sh

@@ -25,7 +25,7 @@ if [[ -z ${ABSEIL_ROOT:-} ]]; then
 fi
 
 if [[ -z ${STD:-} ]]; then
-  STD="c++14 c++17 c++20"
+  STD="c++17 c++20"
 fi
 
 if [[ -z ${COMPILATION_MODE:-} ]]; then

ci/linux_clang-latest_libcxx_bazel.sh

@@ -25,7 +25,7 @@ if [[ -z ${ABSEIL_ROOT:-} ]]; then
 fi
 
 if [[ -z ${STD:-} ]]; then
-  STD="c++14 c++17 c++20"
+  STD="c++17 c++20"
 fi
 
 if [[ -z ${COMPILATION_MODE:-} ]]; then

ci/linux_clang-latest_libcxx_tsan_bazel.sh

@@ -25,7 +25,7 @@ if [[ -z ${ABSEIL_ROOT:-} ]]; then
 fi
 
 if [[ -z ${STD:-} ]]; then
-  STD="c++14 c++17 c++20"
+  STD="c++17 c++20"
 fi
 
 if [[ -z ${COMPILATION_MODE:-} ]]; then