Update project to C++17

- Bump CMake to minimum version 3.8
- Set C++ standard to 17
- Remove CMAKE_LEGACY_CYGWIN_WIN32 compatibility mode
- Remove C++11 stuff
- Update documentation

Signed-off-by: Thomas Lauf <thomas.lauf@tngtech.com>

CMakeLists.txt

@@ -1,5 +1,5 @@
-cmake_minimum_required (VERSION 2.8.12)
+cmake_minimum_required (VERSION 3.8)
-set (CMAKE_LEGACY_CYGWIN_WIN32 0) # Remove when CMake >= 2.8.4 is required
+set (CMAKE_CXX_STANDARD 17)
 set (CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake")
 set (HAVE_CMAKE true)
 

CONTRIBUTING.md

@@ -206,5 +206,5 @@ To be a little more explicit, the common elements across the languages are:
 
 We target Python 3 so that our test suite runs on the broadest set of platforms.
 
-We can safely target C++14 because all the default compilers on our supported platforms are ready.
+We can safely target C++17 because all the default compilers on our supported platforms are ready.
-Feel free to use C++17 and C++20 provided that all build platforms support this.
+Feel free to use C++20 provided that all build platforms support this.

ChangeLog

@@ -11,6 +11,7 @@
 -         Use local man pages in tests
           (thanks to Maxim Beder)
 -         Cleanup CMake files
+-         Update project to C++17
 
 ------ current release ---------------------------
 

INSTALL

@@ -11,9 +11,9 @@ In order to build Timewarrior, you will need:
   - make
   - asciidoctor (for building documentation)
 
-You will need a C++ compiler that supports full C++14, which includes:
+You will need a C++ compiler that supports full C++17, which includes:
-  - gcc 6.1
+  - gcc 8
-  - clang 3.4
+  - clang 5
 
 
 # Basic Installation

README.md

@@ -38,9 +38,9 @@ Thanks to the community, there are binary packages available [here](https://time
 Building Timewarrior yourself requires
 
 * git
-* cmake
+* cmake (>= 3.8)
 * make
-* C++ compiler with full C++14 support, currently gcc 6.1+ or clang 3.4+ 
+* C++ compiler with full C++17 support, currently gcc 8+ or clang 5+ 
 * Python 3 (for running the testsuite)
 * Asciidoctor (for creating documentation)
 

cmake/CXXSniffer.cmake

@@ -1,30 +1,10 @@
-message ("-- Configuring C++11")
 message ("-- System: ${CMAKE_SYSTEM_NAME}")
 
-include (CheckCXXCompilerFlag)
-
-# NOTE: Phase out -std=gnu++0x and --std=c++0x as soon as realistically possible.
-CHECK_CXX_COMPILER_FLAG("-std=c++11"   _HAS_CXX11)
-CHECK_CXX_COMPILER_FLAG("-std=c++0x"   _HAS_CXX0X)
-CHECK_CXX_COMPILER_FLAG("-std=gnu++0x" _HAS_GNU0X)
-
-if (_HAS_CXX11)
-  set (_CXX11_FLAGS "-std=c++11")
-elseif (_HAS_CXX0X)
-  message (WARNING "Enabling -std=c++0x draft compile flag. Your compiler does not support the standard '-std=c++11' option.  Consider upgrading.")
-  set (_CXX11_FLAGS "-std=c++0x")
-elseif (_HAS_GNU0X)
-  message (WARNING "Enabling -std=gnu++0x draft compile flag. Your compiler does not support the standard '-std=c++11' option. Consider upgrading.")
-  set (_CXX11_FLAGS "-std=gnu++0x")
-else (_HAS_CXX11)
- message (FATAL_ERROR "C++11 support missing. Try upgrading your C++ compiler. If you have a good reason for using an outdated compiler, please let us know at support@gothenburgbitfactory.org.")
-endif (_HAS_CXX11)
-
 if (${CMAKE_SYSTEM_NAME} MATCHES "Linux")
   set (LINUX true)
 elseif (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
   set (DARWIN true)
-  set (_CXX11_FLAGS "${_CXX11_FLAGS} -stdlib=libc++")
+  set (CMAKE_CXX_FLAGS "-stdlib=libc++ ${CMAKE_CXX_FLAGS}")
 elseif (${CMAKE_SYSTEM_NAME} MATCHES "kFreeBSD")
   set (KFREEBSD true)
 elseif (${CMAKE_SYSTEM_NAME} MATCHES "FreeBSD")
@@ -41,13 +21,8 @@ elseif (${CMAKE_SYSTEM_NAME} STREQUAL "GNU")
   set (GNUHURD true)
 elseif (${CMAKE_SYSTEM_NAME} STREQUAL "CYGWIN")
   set (CYGWIN true)
-  # NOTE: Not setting -std=gnu++0x leads to compile errors even with
-  #       GCC 4.8.3, and debugging those leads to insanity. Adding this
-  #       workaround instead of fixing Cygwin.
-  set (_CXX11_FLAGS "-std=gnu++0x")
 else (${CMAKE_SYSTEM_NAME} MATCHES "Linux")
   set (UNKNOWN true)
 endif (${CMAKE_SYSTEM_NAME} MATCHES "Linux")
 
-set (CMAKE_CXX_FLAGS "${_CXX11_FLAGS} ${CMAKE_CXX_FLAGS}")
 set (CMAKE_CXX_FLAGS "-Wall -Wextra -Wsign-compare -Wreturn-type ${CMAKE_CXX_FLAGS}")

doc/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required (VERSION 2.8.12)
+cmake_minimum_required (VERSION 3.8)
 
 message ("-- Configuring documentation")
 

doc/holidays/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required (VERSION 2.8.12)
+cmake_minimum_required (VERSION 3.8)
 
 message ("-- Configuring holiday documentation")
 

doc/man1/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required (VERSION 2.8.12)
+cmake_minimum_required (VERSION 3.8)
 
 file (GLOB DOC_SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/*.1.adoc")
 set (DOC_FILES)

doc/man7/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required (VERSION 2.8.12)
+cmake_minimum_required (VERSION 3.8)
 
 file (GLOB DOC_SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/*.7.adoc")
 set (DOC_FILES)

doc/themes/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required (VERSION 2.8.12)
+cmake_minimum_required (VERSION 3.8)
 
 message ("-- Configuring theme documentation")
 

ext/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required (VERSION 2.8.12)
+cmake_minimum_required (VERSION 3.8)
 
 message ("-- Configuring extensions")
 

src/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required (VERSION 2.8.12)
+cmake_minimum_required (VERSION 3.8)
 include_directories (${CMAKE_SOURCE_DIR}
                      ${CMAKE_SOURCE_DIR}/src
                      ${CMAKE_SOURCE_DIR}/src/commands

src/commands/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required (VERSION 2.8.12)
+cmake_minimum_required (VERSION 3.8)
 include_directories (${CMAKE_SOURCE_DIR}
                      ${CMAKE_SOURCE_DIR}/src
                      ${CMAKE_SOURCE_DIR}/src/commands

test/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required (VERSION 2.8.12)
+cmake_minimum_required (VERSION 3.8)
 
 # This is a work-around for the following CMake issue:
 # https://gitlab.kitware.com/cmake/cmake/issues/16062