It could be so easy, but with every MacOS release several things change and some break — again so with MacOS Catalina (aka MacOS 10.15).
For GCC compilation, the directory /usr/include finally is gone for good (no .pkg-file to install aftwards to make it available again — see previous entry on GCC on MacOS 10.14).
With /usr/include gone, one needs to specify the SDK’s directory containing the native system files:
--with-build-sysroot=/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/
The MacOS system header files have evolved. Bootstrapping the compiler fails compiling in libstdc++/libsupc++ the file atexit_thread.cc:
libtool: compile: /Users/hpcraink/DATA/SOFTWARE/gcc-svn/BUILD-MacOS/./gcc/xgcc -shared-libgcc -B/Users/hpcraink/DATA/SOFTWARE/gcc-svn/BUILD-MacOS/./gcc -nostdinc++ -L/Users/hpcraink/DATA/SOFTWARE/gcc-svn/BUILD-MacOS/x86_64-apple-darwin19.0.0/libstdc++-v3/src -L/Users/hpcraink/DATA/SOFTWARE/gcc-svn/BUILD-MacOS/x86_64-apple-darwin19.0.0/libstdc++-v3/src/.libs -L/Users/hpcraink/DATA/SOFTWARE/gcc-svn/BUILD-MacOS/x86_64-apple-darwin19.0.0/libstdc++-v3/libsupc++/.libs -B/Users/hpcraink/DATA/SOFTWARE/gcc-svn/BUILD-MacOS/usr/x86_64-apple-darwin19.0.0/bin/ -B/Users/hpcraink/DATA/SOFTWARE/gcc-svn/BUILD-MacOS/usr/x86_64-apple-darwin19.0.0/lib/ -isystem /Users/hpcraink/DATA/SOFTWARE/gcc-svn/BUILD-MacOS/usr/x86_64-apple-darwin19.0.0/include -isystem /Users/hpcraink/DATA/SOFTWARE/gcc-svn/BUILD-MacOS/usr/x86_64-apple-darwin19.0.0/sys-include --sysroot=/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/ -fno-checking -I/Users/hpcraink/DATA/SOFTWARE/gcc-svn/libstdc++-v3/../libgcc -I/Users/hpcraink/DATA/SOFTWARE/gcc-svn/BUILD-MacOS/x86_64-apple-darwin19.0.0/libstdc++-v3/include/x86_64-apple-darwin19.0.0 -I/Users/hpcraink/DATA/SOFTWARE/gcc-svn/BUILD-MacOS/x86_64-apple-darwin19.0.0/libstdc++-v3/include -I/Users/hpcraink/DATA/SOFTWARE/gcc-svn/libstdc++-v3/libsupc++ -D_GLIBCXX_SHARED -fno-implicit-templates -Wall -Wextra -Wwrite-strings -Wcast-qual -Wabi=2 -fdiagnostics-show-location=once -ffunction-sections -fdata-sections -frandom-seed=atexit_thread.lo -g -O2 -c ../../../../libstdc++-v3/libsupc++/atexit_thread.cc -fno-common -DPIC -D_GLIBCXX_SHARED -o atexit_thread.o In file included from /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/wait.h:110, from /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/stdlib.h:66, from /Users/hpcraink/DATA/SOFTWARE/gcc-svn/BUILD-MacOS/x86_64-apple-darwin19.0.0/libstdc++-v3/include/cstdlib:75, from ../../../../libstdc++-v3/libsupc++/atexit_thread.cc:25: /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/sys/resource.h:443:34: error: expected initializer before ‘__OSX_AVAILABLE_STARTING’ 443 | int getiopolicy_np(int, int) __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0); | ^~~~~~~~~~~~~~~~~~~~~~~~
This is due to the system header’s file Availability.h not defining the macro __OSX_AVAILABLE_STARTING, since the just-compiled cc1 does not offer defined(__has_feature)…
One needs to amend the header Availability.h with the following patch:
--- Availability.h 2019-11-10 15:02:48.000000000 +0100 +++ Availability.h.WORKS 2019-11-10 15:05:10.000000000 +0100 @@ -290,6 +290,12 @@ #define __OSX_AVAILABLE_BUT_DEPRECATED_MSG(_osxIntro, _osxDep, _iosIntro, _iosDep, _msg) #endif #endif + + #ifndef __OSX_AVAILABLE_STARTING + #define __OSX_AVAILABLE_STARTING(_osx, _ios) + #define __OSX_AVAILABLE_BUT_DEPRECATED(_osxIntro, _osxDep, _iosIntro, _iosDep) + #define __OSX_AVAILABLE_BUT_DEPRECATED_MSG(_osxIntro, _osxDep, _iosIntro, _iosDep, _msg) + #endif #endif /* __OSX_AVAILABLE_STARTING */ #else