How to detect which C++11 features are used in my source code

Question

Let us say I've written this C++ program (that essentially is doing nothing)

#include <cstdlib>  int main(int argc, char *argv[]) {   enum class Color { Red, Orange, Yellow, Green, Blue, Violet };   constexpr float a = 3.1415f;   auto b = a;   return EXIT_SUCCESS; } 

Is there a way to detect which C++11 features that are used in my program? Is there maybe some other program that could extract this information out of my source code? Such a program could output a list of features:

$ cat main.cc | some-clever-software N2347 N1984 N2235 

(Alternatively it could output URL:s http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1984.pdf instead)

If I had such a list it would be easier to write a CMakeLists.txt that makes use of the CMake command target_compile_features(), such as this one

cmake_minimum_required(VERSION 3.1.0 FATAL_ERROR) project(foobar CXX) add_executable(foobar main.cc)                                                                                                                                                                                                                                                      set(needed_features     cxx_strong_enums     cxx_constexpr     cxx_auto_type) target_compile_features(foobar PRIVATE ${needed_features}) 

The C++11 features that CMake let us choose from are listed in the CMake variable CMAKE_CXX_KNOWN_FEATURES. I know that the CMake command target_compile_features() has not yet been released in a stable CMake release. It currently lives in the development branch so it might come to change in the future. But nevertheless I'm interested if it is possible to detect what C++11 features are used in some C++ source code.

Update:

Compiling without the -std=c++11 compiler option was suggested in a comment:

First compiling with g++

$ g++ --version g++ (Ubuntu/Linaro 4.8.1-10ubuntu9) 4.8.1 Copyright (C) 2013 Free Software Foundation, Inc. This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  $ g++ main.cc main.cc: In function ‘int main(int, char**)’: main.cc:4:3: warning: scoped enums only available with -std=c++11 or -std=gnu++11 [enabled by default]    enum class Color { Red, Orange, Yellow, Green, Blue, Violet };    ^ main.cc:5:3: error: ‘constexpr’ was not declared in this scope    constexpr float a = 3.1415f;    ^ main.cc:5:13: error: expected ‘;’ before ‘float’    constexpr float a = 3.1415f;              ^ main.cc:6:8: error: ‘b’ does not name a type    auto b = a;         ^ 

and then compiling with clang

$ clang --version Debian clang version 3.2-7ubuntu1 (tags/RELEASE_32/final) (based on LLVM 3.2) Target: x86_64-pc-linux-gnu Thread model: posix $ clang main.cc main.cc:4:8: error: expected identifier or '{'   enum class Color { Red, Orange, Yellow, Green, Blue, Violet };        ^ main.cc:4:3: warning: declaration does not declare anything [-Wmissing-declarations]   enum class Color { Red, Orange, Yellow, Green, Blue, Violet };   ^~~~ main.cc:5:3: error: unknown type name 'constexpr'   constexpr float a = 3.1415f;   ^ main.cc:5:13: error: expected unqualified-id   constexpr float a = 3.1415f;             ^ main.cc:6:3: warning: 'auto' type specifier is a C++11 extension [-Wc++11-extensions]   auto b = a;   ^ main.cc:6:12: error: use of undeclared identifier 'a'   auto b = a;            ^ 2 warnings and 4 errors generated. $ 

Of course, the diagnostics from the compilers give me good hints of which C++11 features that are in use. But what I would like to have is more fine-grained information:

N2235

instead of

error: ‘constexpr’ was not declared in this scope

Answer 1

As said before, this is static analysis of source code. With some simple grep, you can be able to identify some C++11 features such as C++11 STL containers, noexcept, use of move semantic, auto ...

For a more subtle analysis, I would recommend the use of clang API to parse the code source. You can easily check whether a function (and know which one!) is deleted, constexpr... With that, you can do what ever you want (create a report, write the CMake file...)

In all case, I don't think there is a all-in-one tool and you will have to write some parts yourself.