mercurial 3.9.1 error: 'swift_name' attribute cannot be applied

[rgacote]

Upgraded two computers to Sierra. Upgraded both to macports 2.3.4. Xcode 8.0 installed on both.

Trying to install mercurial (version 3.9.1). One computer installs without problems. Other fails with following error:

building 'mercurial.osutil' extension
/usr/bin/clang -fno-strict-aliasing -fno-common -dynamic -pipe -Os -fwrapv -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -I/opt/local/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c mercurial/osutil.c -o build/temp.macosx-10.12-x86_64-2.7/mercurial/osutil.o
In file included from mercurial/osutil.c:862:
In file included from /System/Library/Frameworks/ApplicationServices.framework/Headers/ApplicationServices.h:27:
In file included from /System/Library/Frameworks/ApplicationServices.framework/Frameworks/ATS.framework/Headers/ATS.h:28:
In file included from /System/Library/Frameworks/ApplicationServices.framework/Frameworks/ATS.framework/Headers/ATSLayoutTypes.h:28:
In file included from /System/Library/Frameworks/ApplicationServices.framework/Frameworks/ATS.framework/Headers/ATSTypes.h:24:
In file included from /System/Library/Frameworks/CoreGraphics.framework/Headers/CGGeometry.h:8:
/System/Library/Frameworks/CoreGraphics.framework/Headers/CGBase.h:282:78: error: 'swift_name' attribute cannot be applied to this declaration
typedef struct  CF_BRIDGED_TYPE(id) __IOSurface *IOSurfaceRef __attribute__((swift_name("IOSurfaceRef")));

Tried multiple rebuilds and cleaning the partial builds. Any thoughts appreciated. --Ray

[ryandesign (Ryan Carsten Schmidt)]

Errors encountered in system headers usually mean you haven't installed the latest version of the Xcode command line tools. Use can use xcode-select --install to do that.

[rgacote]

Confirmed that latest XCode is installed. Ray xcode-select --install and it said it was already installed. Tried xcode-select --reset and then rebuild. Same problem. Also confirmed that I've run XCode so the license is accepted.

[seanfarley (Sean Farley)]

Don't know what to tell you, buddy. Mercurial is written in Python with some C extensions. No swift whatsoever. You might need to install the command line tools via the Xcode app (or agree to the license; I forget the dance).