问题
After upgrading to Catalina from Mojave, Setuping: /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk in the env.
I'm unable to compile a program that use <cmath> header.
I tried changing CFLAGS, CCFLAGS, CXXFLAGS to point to the MacOSSDK Location that change nothing
Scanning dependencies of target OgreMain
/Applications/Xcode.app/Contents/Developer/usr/bin/make -f OgreMain/CMakeFiles/OgreMain.dir/build.make OgreMain/CMakeFiles/OgreMain.dir/build
[ 0%] Building CXX object OgreMain/CMakeFiles/OgreMain.dir/src/OgreASTCCodec.cpp.o
cd /Users/roman/Downloads/ogre-1.12.2/build/OgreMain && /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ -DOgreMain_EXPORTS -D__ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORES=0 -I/Users/roman/Downloads/ogre-1.12.2/OgreMain/src/OSX -I/Users/roman/Downloads/ogre-1.12.2/OgreMain/include/Threading -I/Users/roman/Downloads/ogre-1.12.2/OgreMain/src -I/Users/roman/Downloads/ogre-1.12.2/build/Dependencies/include -I/Users/roman/Downloads/ogre-1.12.2/OgreMain/include -I/Users/roman/Downloads/ogre-1.12.2/build/include -I/Users/roman/Downloads/ogre-1.12.2/OgreMain -isystem /usr/local/include -Wall -Winit-self -Wcast-qual -Wwrite-strings -Wextra -Wundef -Wmissing-declarations -Wno-unused-parameter -Wshadow -Wno-missing-field-initializers -Wno-long-long -Wno-inconsistent-missing-override -msse -O3 -DNDEBUG -arch x86_64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk -fPIC -fvisibility=hidden -fvisibility-inlines-hidden -std=c++11 -o CMakeFiles/OgreMain.dir/src/OgreASTCCodec.cpp.o -c /Users/roman/Downloads/ogre-1.12.2/OgreMain/src/OgreASTCCodec.cpp
In file included from /Users/roman/Downloads/ogre-1.12.2/OgreMain/src/OgreASTCCodec.cpp:29:
In file included from /Users/roman/Downloads/ogre-1.12.2/OgreMain/src/OgreStableHeaders.h:40:
In file included from /Users/roman/Downloads/ogre-1.12.2/OgreMain/include/OgrePrerequisites.h:309:
In file included from /Users/roman/Downloads/ogre-1.12.2/OgreMain/include/OgreStdHeaders.h:10:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath:314:9: 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:315:9: 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:316:9: error: no member named 'isfinite' in the global namespace; did you mean 'finite'?
using ::isfinite;
for example the macro: isless is present in the global namespace and on my computer:
➜ cat math.h | grep "isless"
#define isless(x, y) __builtin_isless((x),(y))
#define islessequal(x, y) __builtin_islessequal((x),(y))
#define islessgreater(x, y) __builtin_islessgreater((x),(y))
➜ pwd
/usr/local/include
➜
Even the cmath header include it:
➜ cat /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/cmath | grep "math.h"
#include <math.h>
And my command line have the option -isystem /usr/local/include
This should work...
回答1:
I'm curious: What compiler are you using? What's the value of CMAKE_OSX_SYSROOT?
I'm fairly convinced this is the result of a wrong CMAKE_OSX_SYSROOT. I had the problem you're describing when using python bindings for clang (where CMake doesn't manage the compiler call), but I managed to recreate the error in CMake by doing:
set(CMAKE_OSX_SYSROOT "") # Reset.
I solved the problem by following the answers to this question: Cannot compile R packages with c++ code after updating to macOS Catalina.
To summarise: On Catalina, /usr/include is purged and protected by SIP. Thus, any project that expects the C headers to be found there will fail to compile. If I remember correctly, Apple recommends to file bug reports to projects that expect C headers in /usr/include.
You must point the build system of the code you're trying to compile to the right headers:
(1) Make sure Xcode is up to date. There's no telling what an outdated Xcode on Catalina might do to your build environment.
(2) Use the -isysroot /sdk/path compiler flag, where /sdk/path is the result of xcrun --show-sdk-path. I'm not sure what CMake's best practice is, but try doing
set(CMAKE_OSX_SYSROOT /sdk/path)
or
set (CMAKE_CXX_FLAGS "[...] -isysroot /sdk/path")
If that solves the problem, you may want to look for a better way to do this in CMake.
Of course, if you're adventurous, you could also disable SIP, as suggested in the answer to my question: /usr/include missing on macOS Catalina (with Xcode 11)
来源：https://stackoverflow.com/questions/58628377/catalina-c-using-cmath-headers-yield-error-no-member-named-signbit-in-th