Catalina C++: Using headers yield error: no member named 'signbit' in the global namespace

Question

After upgrading to Catalina from Mojave, Setuping: /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk in the env.

I\

Answer 1

It is possible your copy of Xcode is corrupted. Check with codesign:

codesign --verify /Applications/Xcode.app

This happened to me, and the problem was corrupted Xcode. Reinstalling fixed it.

Something had modified the following:

file added: /Applications/Xcode-11.3.1-.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/json/__pycache__/scanner.cpython-37.pyc
file added: /Applications/Xcode-11.3.1-.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/json/__pycache__/decoder.cpython-37.pyc
file added: /Applications/Xcode-11.3.1-.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/json/__pycache__/encoder.cpython-37.pyc
file added: /Applications/Xcode-11.3.1-.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/lib/python3.7/json/__pycache__/__init__.cpython-37.pyc
file modified: /Applications/Xcode-11.3.1-.app/Contents/Developer/Platforms/AppleTVOS.platform/Developer/SDKs/AppleTVOS.sdk/usr/include/math.h
file modified: /Applications/Xcode-11.3.1-.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk/usr/include/math.h
file modified: /Applications/Xcode-11.3.1-.app/Contents/Developer/Platforms/WatchOS.platform/Developer/SDKs/WatchOS.sdk/usr/include/math.h
file modified: /Applications/Xcode-11.3.1-.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/math.h
file modified: /Applications/Xcode-11.3.1-.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks/Kernel.framework/Versions/A/Headers/math.h
file modified: /Applications/Xcode-11.3.1-.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/DriverKit19.0.sdk/System/DriverKit/usr/include/math.h
file modified: /Applications/Xcode-11.3.1-.app/Contents/Developer/Platforms/WatchSimulator.platform/Developer/SDKs/WatchSimulator.sdk/usr/include/math.h
file modified: /Applications/Xcode-11.3.1-.app/Contents/Developer/Platforms/AppleTVSimulator.platform/Developer/SDKs/AppleTVSimulator.sdk/usr/include/math.h
file modified: /Applications/Xcode-11.3.1-.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/usr/include/math.h

math.h was empty in all the above places.

Answer 2

You may try to use the CommandLineTools SDK rather than the XCode.app SDK.

I fix this problem when I compiling PointCloudLibrary (PCL)

#Check the current sdk
xcrun --show-sdk-path

#Change sdk
sudo xcode-select -s /Library/Developer/CommandLineTools          #Using CommandLineTools SDK
sudo xcode-select -s /Applications/Xcode.app/Contents/Developer   #Using XCode.app SDK

Also, reinstall XCode.app and CommandLineTools may help.

Answer 3

@mkl 's solution helps to fix the similar issue on my side. Thanks.

Issue and solution on my side

I got the same issue to compile a project on basis of PCL. The solution is to set CommandLineTools SDK CMAKE_OSX_SYSROOT.

I tried @mkl's solution to do it in CMakeLists.txt, it doesn't work. So that I can only set it by cmake .. -DCMAKE_OSX_SYSROOT="/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk"

Another thing to mention: there are two versions of command line SDKs in my MacOS:

~ » /Library/Developer/CommandLineTools/SDKs/MacOSX
/Library/Developer/CommandLineTools/SDKs/MacOSX
MacOSX.sdk/       MacOSX10.14.sdk@

xcrun --show-sdk-path gives out the default one, but actually only MacOSX10.14.sdk works on my side.

Discussion of the similar issue in PCL's repo: https://github.com/PointCloudLibrary/pcl/issues/2601#issuecomment-621889211

Difference between SDKs

I don't know much about cmake and SDKs in c++. The difference I noticed in cmake building log from different SDKs as following:

/Library/Developer/CommandLineTools/SDKs/MacOSX:

-- Found OpenGL: /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/OpenGL.framework

/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk

-- Found OpenGL: /Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/System/Library/Frameworks/OpenGL.framework

On default:

-- Found OpenGL: /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/System/Library/Frameworks/OpenGL.framework

Seems like the issue happens on SDK choice for Opengl.

How to do it in CMakeLists.txt?

Appreciated it if anyone could advice.

Answer 4

Reinstalling Xcode, command tools and homebrew, and

sudo rm -rf /usr/local/include

fixed this issue for me.

Answer 5

Summary: in my case, the build script was using an older version of ios-cmake toolchain (2.1.2), and updating it to 3.1.2 fixed the cmath/math include issue.

Adapting the nifty command proposed by @Ryan H. gcc -Wp,-v -E - for my case (clang, c++, iOs target)

clang -x c++ -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk -Wp, -v -E -

yields on two Catalina including a virgin one where only tool ever installed is XCode 11.14.1:

 clang -cc1 version 11.0.3 (clang-1103.0.32.59) default target x86_64-apple-darwin19.4.0
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk/usr/include/c++/v1"
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk/usr/local/include"
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk/Library/Frameworks"
#include "..." search starts here:
#include <...> search starts here:
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/11.0.3/include
 /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk/usr/include
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
 /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk/System/Library/Frameworks (framework directory)
End of search list.

So the correct include path is the first non-ignored one, everything should work OK, but it didn't. It appears the issue came from an additional include command appended to the compilation call by the ios-cmake toolchain:

CompileC /Users/<...>/build.Release.ios/<...>.o <...>.cpp normal arm64 c++ com.apple.compilers.llvm.clang.1_0.compiler
-Isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk <...>
 -I/Users/<...>/Build_iOS/build.Release.ios/build.arm/Binaries/Release/include
 -Isystem /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk/usr/include
 -I/Users/<...>/Build_iOS/build.Release.ios/build.arm/src/<...>.build/Release-iphoneos/<...>/DerivedSources/arm64
...

The culprit was the -Isystem ... line, which will cause the #include <math> line in the cmath file to end up loading the wrong file. After much fiddling around trying to fix the cmake scripts, I noticed the older version of ios-cmake, and updating it had the 'only' effect of removing the unwanted -Isystem line - everything else was almost the same (apart from a few compiler option)

Answer 6

I am having the same problem while trying to target iOS (both on my MacBook Air and on GitHub Actions runner) and here are a few more thoughts on the problem even though I'm not familiar enough with Apple's ecosystem to suggest a proper solution. The original command line was coming from CMake in cpprestsdk, but once I boiled it down to essentials, here is a short repro.

1. Create file cmath-bug.cpp with the only line in it:

    #include <cmath>

2. Run (newlines in front of some arguments are for reading convenience, remove them)

clang -v -x c++ -target arm64-apple-ios13.2 -fcolor-diagnostics -std=c++11 -stdlib=libc++ 
-isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk 
-isystem  /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk/usr/include
-c cmath-bug.cpp

When I run it, i get the familiar to many facing the same issue:

Apple clang version 11.0.0 (clang-1100.0.33.16)
Target: arm64-apple-ios13.2
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
 "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang" -cc1 -triple arm64-apple-ios13.2.0 -Wdeprecated-objc-isa-usage -Werror=deprecated-objc-isa-usage -Werror=implicit-function-declaration -emit-obj -mrelax-all -disable-free -disable-llvm-verifier -discard-value-names -main-file-name cmath-bug.cpp -mrelocation-model pic -pic-level 2 -mthread-model posix -mdisable-fp-elim -fno-strict-return -masm-verbose -munwind-tables -target-sdk-version=13.2 -target-cpu cyclone -target-feature +fp-armv8 -target-feature +neon -target-feature +crypto -target-feature +zcm -target-feature +zcz -target-feature +sha2 -target-feature +aes -target-abi darwinpcs -fallow-half-arguments-and-returns -dwarf-column-info -debugger-tuning=lldb -ggnu-pubnames -target-linker-version 530 -v -coverage-notes-file /Users/myuser/Projects/C++/cmath-bug.gcno -resource-dir /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/11.0.0 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk -isystem /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk/usr/include -stdlib=libc++ -internal-isystem /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1 -Wno-framework-include-private-from-public -Wno-atimport-in-framework-header -Wno-extra-semi-stmt -Wno-quoted-include-in-framework-header -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /Users/myuser/Projects/C++ -ferror-limit 19 -fmessage-length 204 -stack-protector 1 -fstack-check -mdarwin-stkchk-strong-link -fblocks -fencode-extended-block-signature -fregister-global-dtors-with-atexit -fobjc-runtime=ios-13.2.0 -fcxx-exceptions -fexceptions -fmax-type-align=16 -fdiagnostics-show-option -fcolor-diagnostics -o cmath-bug.o -x c++ cmath-bug.cpp
clang -cc1 version 11.0.0 (clang-1100.0.33.16) default target x86_64-apple-darwin19.0.0
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk/usr/include/c++/v1"
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk/usr/local/include"
ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk/Library/Frameworks"
ignoring duplicate directory "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk/usr/include"
#include "..." search starts here:
#include <...> search starts here:
 /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk/usr/include
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/11.0.0/include
 /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include
 /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk/System/Library/Frameworks (framework directory)
End of search list.
In file included from cmath-bug.cpp:1:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:318:9: error: no member named 'signbit' in the global namespace
using ::signbit;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:319:9: error: no member named 'fpclassify' in the global namespace
using ::fpclassify;
      ~~^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:320:9: error: no member named 'isfinite' in the global namespace; did you mean 'finite'?
using ::isfinite;
      ~~^

The only 2 include directories I pass on my original command line exist and are:

$ ls -alF /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk
lrwxr-xr-x  1 root  wheel    12B Dec 17 11:54 /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk@ -> iPhoneOS.sdk
$ ls -alF /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk/usr/include
total 2160
drwxr-xr-x  169 root  wheel   5.3K Dec 17 12:07 ./
drwxr-xr-x    5 root  wheel   160B Nov  4 19:22 ../
 ...
-rw-r--r--    9 root  wheel    32K Nov  4 19:52 math.h
 ...

But the interesting bits here are the non-existing include directories it reports as well as the include directories it ends up searching eventually and their order. My guess is that additional directories not mentioned on the command line are inserted by Apple Clang's driver based on some Apple-specific logic.

You can see from the reported error that the <cmath> header is found at: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/cmath and at line 304 of it you can see:

#include <__config>      // Line 304
#include <math.h>        // This one ends up causing troubles
#include <__cxx_version>

Judging from the fact that in that same folder /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++/v1/ there is a file math.h that provides the necessary definitions, e.g.:

#include <__config>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif

#include_next <math.h>

#ifdef __cplusplus

// We support including .h headers inside 'extern "C"' contexts, so switch
// back to C++ linkage before including these C++ headers.
extern "C++" {

#include <type_traits>
#include <limits>

// signbit

#ifdef signbit

template <class _A1>
_LIBCPP_INLINE_VISIBILITY
bool
__libcpp_signbit(_A1 __lcpp_x) _NOEXCEPT
{
    return signbit(__lcpp_x);
}

#undef signbit

template <class _A1>
inline _LIBCPP_INLINE_VISIBILITY
typename std::enable_if<std::is_floating_point<_A1>::value, bool>::type
signbit(_A1 __lcpp_x) _NOEXCEPT
{
    return __libcpp_signbit((typename std::__promote<_A1>::type)__lcpp_x);
}

...

#elif defined(_LIBCPP_MSVCRT)
...
#endif  // signbit

the authors of <cmath> were expecting the math.h from that same folder be included first and then the #include_next <math.h> directive find the system-specific math.h. That is not what's happening in reality however.

If you look at the first 2 entries in searched directories:

#include <...> search starts here:
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk/usr/include
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1

you see that system-specific include directory ends up being above the Clang-injected standard library directory, which is why the system-specific math.h is being found, not the one in the same folder as the rest of the standard library headers. This is likely the case because if I explicitly add the standard library include directory to my command line BEFORE the other two directories -isystem /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1 the problem goes away and I am able to compile the file. That's not what Clang's driver or whatever else is involved here does automatically: it adds that standard library directory via -internal-system (not sure what's the semantics of that internal flag) and it adds it AFTER the system directory.

Now if you look at the list of ignored directories, the very first entry in that list is:

ignoring nonexistent directory "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk/usr/include/c++/v1"

of which the trailing c++/v1 part does not exist on my machine, making me wonder whether the iPhone SDK installation was supposed to create a symbolic link c++ inside the existing part of the path to point to /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++ directory to make the whole thing work.

Anyways, this what I think is happening and I wonder if anyone knows how to properly fix this?

Thank you!

P.S. For the context:

$ xcode-select -p
/Applications/Xcode.app/Contents/Developer
$ xcrun --show-sdk-path -sdk iphoneos13.2
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.2.sdk