cannot build on Mac

[SeekPoint]

@localhost pyre2 % make CFLAGS='-fPIC -c -Wall -Wno-sign-compare -O3 -g -I.'
python3 setup.py build
running build
running build_py
running build_ext
building '_re2' extension
clang -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk -I/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include -I/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/System/Library/Frameworks/Tk.framework/Versions/8.5/Headers -fPIC -c -Wall -Wno-sign-compare -O3 -g -I. -I/usr/local/include -I/usr/local/opt/openssl@1.1/include -I/usr/local/opt/sqlite/include -I/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/include/python3.8 -c _re2.cc -o build/temp.macosx-10.15-x86_64-3.8/_re2.o -std=c++11
_re2.cc:211:3: warning: suggest braces around initialization of subobject [-Wmissing-braces]
PyObject_HEAD_INIT(NULL)
^~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/include/python3.8/object.h:85:5: note: expanded from macro 'PyObject_HEAD_INIT'
1, type },
^~~~~~~
_re2.cc:255:3: warning: suggest braces around initialization of subobject [-Wmissing-braces]
PyObject_HEAD_INIT(NULL)
^~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/include/python3.8/object.h:85:5: note: expanded from macro 'PyObject_HEAD_INIT'
1, type },
^~~~~~~
_re2.cc:299:3: warning: suggest braces around initialization of subobject [-Wmissing-braces]
PyObject_HEAD_INIT(NULL)
^~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/include/python3.8/object.h:85:5: note: expanded from macro 'PyObject_HEAD_INIT'
1, type },
^~~~~~~
3 warnings generated.
clang++ -bundle -undefined dynamic_lookup -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk -fPIC -c -Wall -Wno-sign-compare -O3 -g -I. build/temp.macosx-10.15-x86_64-3.8/_re2.o -L/usr/local/lib -L/usr/local/opt/openssl@1.1/lib -L/usr/local/opt/sqlite/lib -lre2 -o build/lib.macosx-10.15-x86_64-3.8/_re2.cpython-38-darwin.so
clang: warning: build/temp.macosx-10.15-x86_64-3.8/_re2.o: 'linker' input unused [-Wunused-command-line-argument]
clang: warning: -lre2: 'linker' input unused [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-bundle' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-undefined dynamic_lookup' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-fPIC' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-O3' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-g' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-I .' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-L/usr/local/lib' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-L/usr/local/opt/openssl@1.1/lib' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-L/usr/local/opt/sqlite/lib' [-Wunused-command-line-argument]
python3 setup.py build_ext -i
running build_ext
building '_re2' extension
clang -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk -I/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include -I/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/System/Library/Frameworks/Tk.framework/Versions/8.5/Headers -fPIC -c -Wall -Wno-sign-compare -O3 -g -I. -I/usr/local/include -I/usr/local/opt/openssl@1.1/include -I/usr/local/opt/sqlite/include -I/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/include/python3.8 -c _re2.cc -o build/temp.macosx-10.15-x86_64-3.8/_re2.o -std=c++11
_re2.cc:211:3: warning: suggest braces around initialization of subobject [-Wmissing-braces]
PyObject_HEAD_INIT(NULL)
^~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/include/python3.8/object.h:85:5: note: expanded from macro 'PyObject_HEAD_INIT'
1, type },
^~~~~~~
_re2.cc:255:3: warning: suggest braces around initialization of subobject [-Wmissing-braces]
PyObject_HEAD_INIT(NULL)
^~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/include/python3.8/object.h:85:5: note: expanded from macro 'PyObject_HEAD_INIT'
1, type },
^~~~~~~
_re2.cc:299:3: warning: suggest braces around initialization of subobject [-Wmissing-braces]
PyObject_HEAD_INIT(NULL)
^~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/Cellar/python@3.8/3.8.5/Frameworks/Python.framework/Versions/3.8/include/python3.8/object.h:85:5: note: expanded from macro 'PyObject_HEAD_INIT'
1, type },
^~~~~~~
3 warnings generated.
clang++ -bundle -undefined dynamic_lookup -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk -fPIC -c -Wall -Wno-sign-compare -O3 -g -I. build/temp.macosx-10.15-x86_64-3.8/_re2.o -L/usr/local/lib -L/usr/local/opt/openssl@1.1/lib -L/usr/local/opt/sqlite/lib -lre2 -o build/lib.macosx-10.15-x86_64-3.8/_re2.cpython-38-darwin.so
clang: warning: build/temp.macosx-10.15-x86_64-3.8/_re2.o: 'linker' input unused [-Wunused-command-line-argument]
clang: warning: -lre2: 'linker' input unused [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-bundle' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-undefined dynamic_lookup' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-fPIC' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-O3' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-g' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-I .' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-L/usr/local/lib' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-L/usr/local/opt/openssl@1.1/lib' [-Wunused-command-line-argument]
clang: warning: argument unused during compilation: '-L/usr/local/opt/sqlite/lib' [-Wunused-command-line-argument]
error: can't copy 'build/lib.macosx-10.15-x86_64-3.8/_re2.cpython-38-darwin.so': doesn't exist or not a regular file
make: *** [build] Error 1
@localhost pyre2 %

[dreiss]

I'm not sure what causes this, and I can't debug since I don't have a Mac. I'd be happy to consider a PR that fixes this.