Update Abseil to 20230125.3, raise minimum requirements to CMake 3.12 and C++14

CMakeLists.txt

@@ -2,10 +2,7 @@ if(WIN32)
     cmake_minimum_required(VERSION 3.15)
     cmake_policy(SET CMP0091 NEW)
 else()
-    cmake_minimum_required(VERSION 3.5)
-    if(POLICY CMP0069)
-        cmake_policy(SET CMP0069 NEW)
-    endif()
+    cmake_minimum_required(VERSION 3.12)
 endif()
 
 project(libsfizz

cmake/SfizzConfig.cmake

@@ -4,10 +4,9 @@ include(CheckCXXCompilerFlag)
 include(CheckCXXSourceCompiles)
 include(GNUWarnings)
 
-# TODO:
 # C++14 is the minimum standard version required by Abseil LTS 20230125.1 and later, see
 # https://github.com/abseil/abseil-cpp/releases/tag/20230125.1
-set(CMAKE_CXX_STANDARD 11 CACHE STRING "C++ standard to be used")
+set(CMAKE_CXX_STANDARD 14 CACHE STRING "C++ standard to be used")
 set(CMAKE_C_STANDARD 99 CACHE STRING "C standard to be used")
 
 # Export the compile_commands.json file

cmake/SfizzDeps.cmake

@@ -52,20 +52,16 @@ if(APPLE)
 endif()
 
 # Add Abseil
+
+# WARNING: When enabling SFIZZ_USE_SYSTEM_ABSEIL and the installed
+# library was built with C++17, the build fails if CMAKE_CXX_STANDARD
+# is set to 14. This happens at least with Archlinux and FreeBSD.
+# We'll need also to check if to set ABSL_PROPAGATE_CXX_STD=OFF in future versions.
 if(SFIZZ_USE_SYSTEM_ABSEIL)
     find_package(absl REQUIRED)
     if(absl_FOUND)
-        # FIXME:
-        # 1. Workaround for silent Abseil module, see #1117
+        # Workaround for silent Abseil module, see #1117
         message(STATUS "Found system Abseil libraries, version ${absl_VERSION}")
-        # 2. The current Abseil LTS version requires at least C++14, see
-        #    https://github.com/abseil/abseil-cpp/releases/tag/20230125.1
-        #    but results in errors by using std::string_view, optional etc.,
-        #    due to an ABI incompatibility with the installed system library
-        #    when built with C++17. This is happens at least with Archlinux and FreeBSD,
-        #    so in cases like these a -D CMAKE_CXX_STANDARD=17 is required.
-        # 3. We'll need also to check if to set ABSL_PROPAGATE_CXX_STD=OFF
-        #    in future versions because the above issue.
 
         # Make Abseil to be usable globally also for plugins project:
         # in CMake 3.24+ we can use `find_package(absl REQUIRED GLOBAL)`,