clang++

Difference on address of const reference to ternary operator between clang and gcc

由 情到浓时终转凉″ 提交于 2019-12-01 03:51:30
问题 I have a vague idea of what's going on here... and it has to do with this but I'm wondering why clang++ and g++ handle this differently. Where is the undefined behaviour arround here? Note: this has nothing to do with templates - I just use them to make the example more compact. It's all about the type of whatever . #include <iostream> #include <vector> template <typename T> void test() { T whatever = 'c'; const char a = 'a'; std::cout << "begin: " << (void*)&a << std::endl; const char & me =

What could cause clang to not find the unordered_map header?

由 空扰寡人 提交于 2019-11-30 20:44:40
I'm trying to compile a program I found on the web using Clang++. The Makefile generates this command: clang++ -c -arch x86_64 -msse3 -std=c++11 -stdlib=libstdc++ -Wno-missing-field-initializers -Wno-missing-prototypes -Wreturn-type -Wno-non-virtual-dtor -Wno-exit-time-destructors -Wformat -Wmissing-braces -Wparentheses -Wno-switch -Wunused-function -Wunused-label -Wno-unused-parameter -Wunused-variable -Wunused-value -Wno-empty-body -Wuninitialized -Wunknown-pragmas -Wno-shadow -Wno-four-char-constants -Wno-conversion -Wconstant-conversion -Wint-conversion -Wno-shorten-64-to-32 -Wenum

template template parameters and clang

由 ￣綄美尐妖づ 提交于 2019-11-30 20:34:44
I have had problems (possibly mine) with template template parameters and clang. The following toy example compiles and runs under g++ 4.7.0, not clang++ 3.0 (based on LLVM 3.0), both ubuntu 12.04. Toy example (test_1.cpp): #include <iostream> #include <memory> struct AFn { void operator()() { ; // do something } }; template<typename T> struct impl { T *backpointer_; }; template<typename S, template <typename> class T> struct implT { T<S> *backpointer_; }; template<typename> class AClass; template<> struct implT<AFn, AClass> { implT(std::string message) : message_(message) {} void operator()()

clang 3.6 fold expression left/right

由 时光毁灭记忆、已成空白 提交于 2019-11-30 19:42:06
I'm trying the fold expression with clang 3.6 '--std=c++1z', but something I don't quite get. The function that I'm testing is: auto minus = [](auto... args) { return (args - ...); }; ... std::cout << minus(10, 3, 2) << std::endl; according to n4191 , I'm expecting it expands as a left fold to (10 - 3) - 2 which gives result 5, however, the result is 9, which seems to be a right fold expansion, i.e. 10 - (3 - 2) Am I missing anything or mis-understand n4191? Thanks n4191 was revised by n4295 . According to that, an expression of the form (e op ...) is a unary right fold , and that is expanded

clang 4 build error on <functional> with c++1z

由 强颜欢笑 提交于 2019-11-30 19:35:18
I just updated my arch linux system to the latest which includes gcc 7.1.1. Trying to build this: #include <functional> int main(int argc, char** argv) { return 1; } using the command clang++ main.cpp -std=c++1z results in the error: In file included from main.cpp:1: In file included from /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/7.1.1/../../../../include/c++/7.1.1/functional:60: In file included from /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/7.1.1/../../../../include/c++/7.1.1/unordered_map:47: In file included from /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/7.1.1/../../../../include/c++/7.1.1

How to force clang to use some library by default?

由 和自甴很熟 提交于 2019-11-30 17:25:17
I build clang by clang against libc++ , libc++abi , compiler-rt in the following steps: To download (and update) llvm and sub-projects I use the following script: svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm cd llvm/tools svn co http://llvm.org/svn/llvm-project/cfe/trunk clang svn co http://llvm.org/svn/llvm-project/clang-tools-extra/trunk clang/tools/extra svn co http://llvm.org/svn/llvm-project/lldb/trunk lldb svn co http://llvm.org/svn/llvm-project/lld/trunk lld svn co http://llvm.org/svn/llvm-project/polly/trunk polly cd ../projects/ svn co http://llvm.org/svn/llvm-project

Prevent standard functions outside of std namespace

由 十年热恋 提交于 2019-11-30 17:20:15
I am using only header files specific to C++ (e.g. <cstdlib> ), however I still get globally-declared functions, and not just functions in the std namespace. Is there a way, perhaps a compiler switch, to prevent that? For example, the following code: #include <cstdlib> float random() { return 0.0f; } int main() { return 0; } Fails to compile under linux, with the following error: > g++ -c main.cpp main.o main.cpp: In function ‘float random()’: main.cpp:2:14: error: new declaration ‘float random()’ /usr/include/stdlib.h:327:17: error: ambiguates old declaration ‘long int random()’ or > clang++

Prevent standard functions outside of std namespace

由 一笑奈何 提交于 2019-11-30 16:38:01
问题 I am using only header files specific to C++ (e.g. <cstdlib> ), however I still get globally-declared functions, and not just functions in the std namespace. Is there a way, perhaps a compiler switch, to prevent that? For example, the following code: #include <cstdlib> float random() { return 0.0f; } int main() { return 0; } Fails to compile under linux, with the following error: > g++ -c main.cpp main.o main.cpp: In function ‘float random()’: main.cpp:2:14: error: new declaration ‘float

default argument, gcc vs clang

由 a 夏天 提交于 2019-11-30 16:29:23
问题 Code looks like: struct Foo { Foo(const char *); }; Foo::Foo(const char *str = 0) { } VS 2013 and gcc 4.8.0 accept such code, while clang 3.3 reject such code with: error: addition of default argument on redeclaration makes this constructor a default constructor who is right from standard (C++03 and C++11) point of view? Note: I like clang's choice too, but I going to report bug to gcc and visual studio, and if this is not correct from standard point of view, this helps to convince compiler's

Misaligned address using virtual inheritance

由 我怕爱的太早我们不能终老 提交于 2019-11-30 14:31:07
The following apparently valid code produces a misaligned address runtime error using the UndefinedBehaviorSanitizer sanitiser. #include <memory> #include <functional> struct A{ std::function<void()> data; // seems to occur only if data is a std::function } ; struct B{ char data; // occurs only if B contains a member variable }; struct C:public virtual A,public B{ }; struct D:public virtual C{ }; void test(){ std::make_shared<D>(); } int main(){ test(); return 0; } Compiling and executing on a macbook with clang++ -fsanitize=undefined --std=c++11 ./test.cpp && ./a.out produces the output
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