Clang >= 3.3 in c++1y mode cannot parse <cstdio> header
c++, c++11, c++14, clang, header
Solution
This note in the `gets` manpage looks relevant:
ISO C11 removes the specification of gets() from the C language, and since version 2.16, glibc header files don't expose the function declaration if the `_ISOC11_SOURCE` feature test macro is defined.
Probably should be
#if !_ISOC11_SOURCE
using ::gets;
#endif
Problem
I have a project that correctly compiles and runs under g++ 4.8.1 and clang >= 3.3 in c++11 mode. However, when I switch to the experimental `-std=c++1y` mode, clang 3.3 (but not g++) chokes on the `<cstdio>` header that is indirectly included by way of Boost.Test (so I cannot easily change it myself) ``` // /usr/include/c++/4.8/cstdio #include <stdio.h> // Get rid of those macros defined in <stdio.h> in lieu of real functions. // ... #undef gets // ... namespace std { // ... using ::gets; // <-- error with clang++ -std=c++1y // ... } ``` with the following error message: /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/cstdio:119:11: error: no member named 'gets' in the global namespace On this tutorial on how to set up a modern C++ environment, a similar lookup problem with `max_align_t` is encountered. The recommendation there is to use a sed script to surround the unknown symbols with `#ifdef __clang__` macros, but that seems a fragile approach. Setup: plain 64-bit Linux Mint 15 with g++ (Ubuntu 4.8.1-2ubuntu1~13.04) 4.8.1 Ubuntu clang version 3.3-3~raring1 (branches/release_33) (based on LLVM 3.3) Questions: - what is causing this erorr? There is no `__clang__` macro anywhere near the code in question, and clang in c++11 mode has no trouble at all. - Is it a language problem (does C++14 say something else than C++11 about importing C compatible symbols from the global into the `std` namespace)? - Do I need to change something with my include paths? (I use CMake to automatically select the header paths, and switch modes inside CMakeLists.txt) - Does clang have a switch to resolve this?