clang++

问题 Here is a reproducible example taken from question about using temporary stringstream object: #include <sstream> #include <string> #include <iostream> using namespace std; std::string transform(std::string); int main() { int i{}; cout << transform( static_cast<stringstream &>(stringstream() << i).str() ); } When trying to compile with clang version 9.0.0 under MacOS High Sierra I got following error: $ clang++ -std=c++11 x.cc -c x.cc:12:24: error: non-const lvalue reference to type 'basic

问题 I've just updated xcode to version 9 and I've started getting the following error message when compiling: clang: error: cannot specify -o when generating multiple output files The issue seems to be linked to compiling with the "Optimization Level" parameter set to "None" (i.e. -O0). If I set this higher the error goes away, BUT when I increase the optimization the debugging tools do not work appropriately (for example variable tracking). I've looked at other questions that list this error,

问题 Given the following code: #include <iostream> #include <optional> struct foo { explicit operator std::optional<int>() { return std::optional<int>( 1 ); } explicit operator int() { return 0; } }; int main() { foo my_foo; std::optional<int> my_opt( my_foo ); std::cout << "value: " << my_opt.value() << std::endl; } gcc 7.2.0 writes value: 1 . MSVC 2017 (15.3) and clang 4.0.0 however write value: 0 . Which one is correct according to the C++ standard? 回答1: Since this is direct-initialization, we

问题 I am trying to link v8's static library to a shared library using the following cmake command add_library(v8jni SHARED ${THIRDPARTY_LIB_PATH}/shared/v8jni.cpp) target_link_libraries(v8jni log -Wl,--whole-archive v8_inspector v8_base v8_snapshot v8_libplatform v8_libsampler v8_libbase -Wl,--no-whole-archive) libv8jni.so is generated successfully. But it's useless because all the v8 function are marked as local. nm -C libv8_base.a | grep v8::HandleScope 00000000 T v8::HandleScope::Initialize(v8

问题 I am trying to use std::experimental::detect_or_t from <experimental/type_traits> . What compiler, option, version or library do I need to compile the following example from http://en.cppreference.com/w/cpp/experimental/is_detected ? #include <experimental/type_traits> #include <cstddef> template<class T> using diff_t = typename T::difference_type; template <class Ptr> using difference_type = std::experimental::detected_or_t<std::ptrdiff_t, diff_t, Ptr>; struct Meow { using difference_type =

问题 I'm trying to link together: libFuzzer.a, compiled with clang++-5.0 and -std=c++11 my fuzz driver, compiled with clang++-5.0 and -std=c++11 -stdlib=libc++ libcurl, compiled with clang-5.0 Specifically, this linker command is being executed: /bin/bash ../../libtool --silent --tag=CXX --mode=link clang++-5.0 -I../../include -I../../lib -I../../lib -I../../tests/fuzz -fsanitize=address -fsanitize-address-use-after-scope -fsanitize-coverage=trace-pc-guard,trace-cmp -std=c++11 -stdlib=libc++ -o

问题 When I compile a simple hello world program using clang, in the comments of the elf64 file I still find information related to GCC. Why? I'm using clang not gcc. I'm using ubuntu 16.04. username@ubuntu:~$ clang++ -stdlib=libc++ test.cpp username@ubuntu:~$ objdump --full-contents --section=.comment a.out a.out: file format elf64-x86-64 Contents of section .comment: 0000 4743433a 20285562 756e7475 20352e34 GCC: (Ubuntu 5.4 0010 2e302d36 7562756e 7475317e 31362e30 .0-6ubuntu1~16.0 0020 342e3429

问题 I want to use libc++ together with clang on Arch Linux in CMake project. I installed libc++ and added following lines to CMakeLists.txt as said on LLVM site in Linux section of "Using libc++ in your programs": set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -stdlib=libc++") set(CMAKE_EXE_LINKER_FLAGS "-lc++abi") I have tried just "++abi" in linker's flags, but it didn't help. I need some help in figuring out what i should write in my CMakeLists.txt. 回答1: Don't forget to set the compiler to

问题 I basically have a class that depends on a non-type template parameter. I defined a casting so an object of non-type template parameter N can convert to another of M . I have a minimal example that can reproduce the situation: template<auto Integral> class Test{ public: typedef decltype(Integral) value_type; static constexpr value_type N = Integral; constexpr Test (const value_type& x = 0); template<auto Integral2> constexpr explicit operator Test<Integral2>() const; private: value_type n; };

问题 I basically have a class that depends on a non-type template parameter. I defined a casting so an object of non-type template parameter N can convert to another of M . I have a minimal example that can reproduce the situation: template<auto Integral> class Test{ public: typedef decltype(Integral) value_type; static constexpr value_type N = Integral; constexpr Test (const value_type& x = 0); template<auto Integral2> constexpr explicit operator Test<Integral2>() const; private: value_type n; };