Recently (since Catalina was released and xcode updated, but I am still running Mojave) I have found the gcc, installed via macports, has broken. I get errors saying that the system includes cannot be found:
ld: library not found for -lSystem
I have tried the solution here: Can't compile C program on a Mac after upgrade to Mojave - but when I install macOS_SDK_headers_for_macOS_10.14.pkg it doesn't actually create anything in /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs ; all I see in there is the 10.15 (Catalina) sdk!
If I instead just sym link MacOSX10.14.sdk to MacOSX10.15.sdk (possibly not a great idea), I get a different set of errors:
In file included from /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/wchar.h:90,
from /opt/local/include/gcc8/c++/cwchar:44,
from /opt/local/include/gcc8/c++/bits/postypes.h:40,
from /opt/local/include/gcc8/c++/iosfwd:40,
from /opt/local/include/gcc8/c++/ios:38,
from /opt/local/include/gcc8/c++/ostream:38,
from /opt/local/include/gcc8/c++/iostream:39,
from /Users/pae9/soft/src/cmake/LIGO_support/restrictHealMap.cpp:4:
/opt/local/lib/gcc8/gcc/x86_64-apple-darwin18/8.3.0/include-fixed/stdio.h:222:7: error: conflicting declaration of 'char* ctermid(char*)' with 'C' linkage
char *ctermid(char *);
In other words, now it appears that the macports headers are conflicting with the xcode ones.
I never had a problem before; I think this issue dates to the last xcode update (currently on Version 11.2 (11B52))
Any thoughts or suggestions very welcome - I'd really like to be able to go back to compiling code using gcc!
FYI I'm using gcc7 (from macports), for consistency with the linux servers which are my actual live systems, but I have tried gcc 8 and 9 and get the same results.
