David Blaikie via llvm-dev
2021-Feb-11 22:25 UTC
[llvm-dev] Clang++: No member name 'make_unique' in namespace 'std'
1) clang++ -v will show you which standard library headers it's using, it might be using an older standard library on your system that doesn't have std::make_unique. 2) Did you build the compiler in release mode, or in debug mode? (with or without assertions enabled) On Thu, Feb 11, 2021 at 2:21 PM users users via llvm-dev <llvm-dev at lists.llvm.org> wrote:> > Dear LLVM Developers: > > 1. Recently I built llvm/12.0 on IBM power8 using gcc/8.2.0. When I run clang++ with an example from https://en.cppreference.com/w/cpp/memory/unique_ptr/make_unique: > > #include <iostream> > > #include <iomanip> > #include <memory> > > struct Vec3 > { > int x, y, z; > > // following constructor is no longer needed since C++20 > Vec3(int x = 0, int y = 0, int z = 0) noexcept : x(x), y(y), z(z) { } > > friend std::ostream& operator<<(std::ostream& os, const Vec3& v) { > return os << "{ x=" << v.x << ", y=" << v.y << ", z=" << v.z << " }"; > } > }; > > int main() > { > // Use the default constructor. > std::unique_ptr<Vec3> v1 = std::make_unique<Vec3>(); > // Use the constructor that matches these arguments > std::unique_ptr<Vec3> v2 = std::make_unique<Vec3>(0,1,2); > // Create a unique_ptr to an array of 5 elements > std::unique_ptr<Vec3[]> v3 = std::make_unique<Vec3[]>(5); > > std::cout << "make_unique<Vec3>(): " << *v1 << '\n' > << "make_unique<Vec3>(0,1,2): " << *v2 << '\n' > << "make_unique<Vec3[]>(5): "; > for (int i = 0; i < 5; i++) { > std::cout << std::setw(i ? 30 : 0) << v3[i] << '\n'; > } > } > > > It failed with the following errors: > Error: no member named 'make_unique' in namespace 'std' > std::unique_ptr<Vec3> v1 = std::make_unique<Vec3>(); > ... ... > > Any idea and suggestion about what is going on? or have I missed something? The command I used to compile the code above: > $ clang++ a.cpp > > 2. Comparing this llvm with my current gcc/8.2.0 on a project (openmp code running 1 thread), it showed that llvm is almost twice as slow as gcc (both compile with -O3) on my IBM power8 machine. Is it suppose to be with such slower performance than gcc? > > Thank you very much for any advice! > > Best Regards, > Shelton > > > > > > > > > > > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
users users via llvm-dev
2021-Feb-11 22:53 UTC
[llvm-dev] Clang++: No member name 'make_unique' in namespace 'std'
Hi David, Thank you so much for your quick response! I am very inexperienced with llvm. Please bear with me if my questions look stupid: 1. Here is the output from the command ss"clang++ -v": $ clang++ -v clang version 12.0.0 (... .../llvm/llvm-project_git/clang 36263a7cccc0d98afc36dea55e7a004d08455811) Target: powerpc64le-unknown-linux-gnu Thread model: posix InstalledDir: ... .../llvm/llvm-project_git/build_12.0.0_36263a7_010421/bin Found candidate GCC installation: /usr/lib/gcc/ppc64le-redhat-linux/4.8.2 Found candidate GCC installation: /usr/lib/gcc/ppc64le-redhat-linux/4.8.5 Selected GCC installation: /usr/lib/gcc/ppc64le-redhat-linux/4.8.5 Candidate multilib: .;@m64 Selected multilib: .;@m64 Before using clang++, I removed gcc modules, because I thought clang++ should not be dependent of any host compiler once it was built successfully. Or does it need to make my host compiler (such as gcc/8.2.0) available to it so that to compile my project? 2. Here are the options I used to build llvm: -DLLVM_ENABLE_PROJECTS="clang;libcxx;libcxxabi;openmp;parallel-libs" -DCMAKE_BUILD_TYPE="Release" -DLLVM_TARGETS_TO_BUILD=PowerPC -DLLVM_ENABLE_LIBPFM=OFF -DRUN_HAVE_GNU_POSIX_REGEX=0 -DRUN_HAVE_THREAD_SAFETY_ATTRIBUTES=0 -Wno-dev ../llvm Are these correct options to use? Please advise. Thank you so much David! Best, Shelton On Thu, Feb 11, 2021 at 4:26 PM David Blaikie <dblaikie at gmail.com> wrote:> 1) clang++ -v will show you which standard library headers it's using, > it might be using an older standard library on your system that > doesn't have std::make_unique. > 2) Did you build the compiler in release mode, or in debug mode? (with > or without assertions enabled) > > On Thu, Feb 11, 2021 at 2:21 PM users users via llvm-dev > <llvm-dev at lists.llvm.org> wrote: > > > > Dear LLVM Developers: > > > > 1. Recently I built llvm/12.0 on IBM power8 using gcc/8.2.0. When I > run clang++ with an example from > https://en.cppreference.com/w/cpp/memory/unique_ptr/make_unique: > > > > #include <iostream> > > > > #include <iomanip> > > #include <memory> > > > > struct Vec3 > > { > > int x, y, z; > > > > // following constructor is no longer needed since C++20 > > Vec3(int x = 0, int y = 0, int z = 0) noexcept : x(x), y(y), z(z) { } > > > > friend std::ostream& operator<<(std::ostream& os, const Vec3& v) { > > return os << "{ x=" << v.x << ", y=" << v.y << ", z=" << v.z << > " }"; > > } > > }; > > > > int main() > > { > > // Use the default constructor. > > std::unique_ptr<Vec3> v1 = std::make_unique<Vec3>(); > > // Use the constructor that matches these arguments > > std::unique_ptr<Vec3> v2 = std::make_unique<Vec3>(0,1,2); > > // Create a unique_ptr to an array of 5 elements > > std::unique_ptr<Vec3[]> v3 = std::make_unique<Vec3[]>(5); > > > > std::cout << "make_unique<Vec3>(): " << *v1 << '\n' > > << "make_unique<Vec3>(0,1,2): " << *v2 << '\n' > > << "make_unique<Vec3[]>(5): "; > > for (int i = 0; i < 5; i++) { > > std::cout << std::setw(i ? 30 : 0) << v3[i] << '\n'; > > } > > } > > > > > > It failed with the following errors: > > Error: no member named 'make_unique' in namespace 'std' > > std::unique_ptr<Vec3> v1 = std::make_unique<Vec3>(); > > ... ... > > > > Any idea and suggestion about what is going on? or have I missed > something? The command I used to compile the code above: > > $ clang++ a.cpp > > > > 2. Comparing this llvm with my current gcc/8.2.0 on a project (openmp > code running 1 thread), it showed that llvm is almost twice as slow as gcc > (both compile with -O3) on my IBM power8 machine. Is it suppose to be with > such slower performance than gcc? > > > > Thank you very much for any advice! > > > > Best Regards, > > Shelton > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > LLVM Developers mailing list > > llvm-dev at lists.llvm.org > > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20210211/3529b9ca/attachment.html>