From fd4fd9a276126a1b1044d57a064c3b8201a91a33 Mon Sep 17 00:00:00 2001 From: Brad King Date: Fri, 11 Aug 2017 13:19:05 -0400 Subject: Require C++11 to build CMake itself CMake can now compile as C++11 on all supported platforms. Check that std::unique_ptr is available and fail early if missing. This will allow us to use C++11 more broadly in CMake's implementation (previously it was restricted to the serve mode implementation). Co-Author: Daniel Pfeifer --- CMakeLists.txt | 4 +++ Help/dev/source.rst | 16 ++++++------ Help/release/dev/require-c++11.rst | 5 ++++ README.rst | 2 +- bootstrap | 51 ++++++++++++++------------------------ 5 files changed, 36 insertions(+), 42 deletions(-) create mode 100644 Help/release/dev/require-c++11.rst diff --git a/CMakeLists.txt b/CMakeLists.txt index e60dc78..bebb000 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -80,6 +80,10 @@ if(NOT CMake_TEST_EXTERNAL_CMAKE) # check for available C++ features include(${CMake_SOURCE_DIR}/Source/Checks/cm_cxx_features.cmake) + + if(NOT CMake_HAVE_CXX_UNIQUE_PTR) + message(FATAL_ERROR "The C++ compiler does not support C++11 (e.g. std::unique_ptr).") + endif() endif() # set the internal encoding of CMake to UTF-8 diff --git a/Help/dev/source.rst b/Help/dev/source.rst index 16a9252..b40a884 100644 --- a/Help/dev/source.rst +++ b/Help/dev/source.rst @@ -23,20 +23,18 @@ format only a subset of files, such as those that are locally modified. C++ Subset Permitted ==================== -CMake supports compiling as C++98 in addition to C++11 and C++14. -In order to support building on older toolchains some constructs -need to be handled with care: +CMake requires compiling as C++11 or above. However, in order to support +building on older toolchains some constructs need to be handled with care: -* Use ``CM_AUTO_PTR`` instead of ``std::auto_ptr``. +* Do not use ``CM_AUTO_PTR`` or ``std::auto_ptr``. - The ``std::auto_ptr`` template is deprecated in C++11. We want to use it - so we can build on C++98 compilers but we do not want to turn off compiler - warnings about deprecated interfaces in general. Use the ``CM_AUTO_PTR`` - macro instead. + The ``std::auto_ptr`` template is deprecated in C++11. The ``CM_AUTO_PTR`` + macro remains leftover from C++98 support until its uses can be ported to + ``std::unique_ptr``. Do not add new uses of the macro. * Use ``CM_EQ_DELETE;`` instead of ``= delete;``. - Defining functions as *deleted* is not supported in C++98. Using + Older C++11 compilers do not support deleting functions. Using ``CM_EQ_DELETE`` will delete the functions if the compiler supports it and give them no implementation otherwise. Calling such a function will lead to compiler errors if the compiler supports *deleted* functions and linker diff --git a/Help/release/dev/require-c++11.rst b/Help/release/dev/require-c++11.rst new file mode 100644 index 0000000..7b849e7 --- /dev/null +++ b/Help/release/dev/require-c++11.rst @@ -0,0 +1,5 @@ +require-c++11 +------------- + +* Support for building CMake itself with C++98 compilers was dropped. + CMake is now implemented using C++11. diff --git a/README.rst b/README.rst index 0946b70..3cef06d 100644 --- a/README.rst +++ b/README.rst @@ -51,7 +51,7 @@ Building CMake from Scratch UNIX/Mac OSX/MinGW/MSYS/Cygwin ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -You need to have a compiler and a make installed. +You need to have a C++ compiler (supporting C++11) and a ``make`` installed. Run the ``bootstrap`` script you find in the source directory of CMake. You can use the ``--help`` option to see the supported options. You may use the ``--prefix=`` option to specify a custom diff --git a/bootstrap b/bootstrap index 9d73233..aee210f 100755 --- a/bootstrap +++ b/bootstrap @@ -1004,58 +1004,45 @@ fi # Check if C++ compiler works TMPFILE=`cmake_tmp_file` echo ' -#if defined(TEST1) -# include -#else -# include -#endif +#include +#include #if __cplusplus >= 201103L && defined(__SUNPRO_CC) && __SUNPRO_CC < 0x5140 #error "SunPro <= 5.13 C++ 11 mode not supported due to bug in move semantics." #endif -class NeedCXX +class Class { public: - NeedCXX() { this->Foo = 1; } - int GetFoo() { return this->Foo; } + int Get() const { return this->Member; } private: - int Foo; + int Member = 1; }; int main() { - NeedCXX c; -#ifdef TEST3 - cout << c.GetFoo() << endl; -#else - std::cout << c.GetFoo() << std::endl; -#endif + auto const c = std::unique_ptr(new Class); + std::cout << c->Get() << std::endl; return 0; } ' > "${TMPFILE}.cxx" -for a in ${cmake_cxx_compilers}; do - for b in 1 2 3; do - if [ -z "${cmake_cxx_compiler}" ] && \ - cmake_try_run "${a}" "${cmake_cxx_flags} -DTEST${b}" "${TMPFILE}.cxx" >> cmake_bootstrap.log 2>&1; then - cmake_cxx_compiler="${a}" - fi - done -done -for std in 14 11 98; do +for std in 17 14 11; do try_flags="`cmake_extract_standard_flags \"${cmake_toolchain}\" CXX \"${std}\"`" - for flag in $try_flags; do - echo "Checking for wheter ${cmake_cxx_flags} supports ${flag}" >> cmake_bootstrap.log 2>&1 - if cmake_try_run "${cmake_cxx_compiler}" "${cmake_cxx_flags} ${flag} -DTEST1" \ - "${TMPFILE}.cxx" >> cmake_bootstrap.log 2>&1; then - cmake_cxx_flags="${cmake_cxx_flags} ${flag} " - break 2 - fi + for compiler in ${cmake_cxx_compilers}; do + for flag in '' $try_flags; do + echo "Checking whether '${compiler} ${cmake_cxx_flags} ${flag}' works." >> cmake_bootstrap.log 2>&1 + if cmake_try_run "${compiler}" "${cmake_cxx_flags} ${flag}" \ + "${TMPFILE}.cxx" >> cmake_bootstrap.log 2>&1; then + cmake_cxx_compiler="${compiler}" + cmake_cxx_flags="${cmake_cxx_flags} ${flag} " + break 3 + fi + done done done rm -f "${TMPFILE}.cxx" if [ -z "${cmake_cxx_compiler}" ]; then - cmake_error 7 "Cannot find appropriate C++ compiler on this system. +cmake_error 7 "Cannot find a C++ compiler supporting C++11 on this system. Please specify one using environment variable CXX. See cmake_bootstrap.log for compilers attempted." fi -- cgit v0.12