ios - g++ 与 iOS sysroot 和 xcode 8.1

Question

使用 Xcode 8.0，我可以使用 sysroot 为 iOS 进行交叉编译:

/Applications/Xcode.app/Contents/Developer/usr/bin/g++ \
    --sysroot=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS10.0.sdk \
    -miphoneos-version-min=10.0 -arch armv7s -stdlib=libc++ -std=gnu++11 \
    helloworld.cpp

但是，在 Xcode 8.1 中，这种情况就会出现问题:

/Applications/Xcode.app/Contents/Developer/usr/bin/g++ \
    --sysroot=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS10.1.sdk \
    -miphoneos-version-min=10.1 -arch armv7s -stdlib=libc++ -std=gnu++11 \
    helloworld.cpp
clang: warning: using sysroot for 'MacOSX' but targeting 'iPhone'
In file included from helloworld.cpp:1:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/iostream:38:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/ios:215:
In file included from /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/iosfwd:90:
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/usr/include/wchar.h:70:
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/usr/include/_types.h:27:
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/usr/include/sys/_types.h:32:
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/usr/include/sys/cdefs.h:761:2: error: Unsupported architecture
#error Unsupported architecture

警告使用 sysroot for 'MacOSX' 但针对 'iPhone' 似乎表明 sysroot 参数被忽略(并且在错误中很明显，它的使用MacOSX10.12.sdk)。

这些论点有改变吗？如何正确指定sysroot？

Answer 1

在较新的 Xcode 中使用 -isysroot 而不是 --sysroot，并使用空格而不是等号。