grpc: Compilation error on macOS (issue with boringssl)

Compile error both using CPython 3.6 and PyPy 6.0.0 (3.5.3) from MacPorts

Python 3.5.3 (fdd60ed87e941677e8ea11acf9f1819466521bf2, Jul 30 2018, 08:59:51)
[PyPy 6.0.0 with GCC 4.2.1 Compatible Apple LLVM 9.1.0 (clang-902.0.39.2)]

Python 3.6.6

Log:

b"In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:115:
/opt/local/include/openssl/e_os2.h:276:11: error: 'OPENSSL_EXPORT' macro redefined [-Werror,-Wmacro-redefined]
#  define OPENSSL_EXPORT extern
          ^
third_party/boringssl/include/openssl/base.h:182:9: note: previous definition is here
#define OPENSSL_EXPORT
        ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:83:31: error: redefinition of typedef 'ASN1_INTEGER' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_INTEGER;
                              ^
third_party/boringssl/include/openssl/base.h:244:31: note: previous definition is here
typedef struct asn1_string_st ASN1_INTEGER;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:84:31: error: redefinition of typedef 'ASN1_ENUMERATED' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_ENUMERATED;
                              ^
third_party/boringssl/include/openssl/base.h:240:31: note: previous definition is here
typedef struct asn1_string_st ASN1_ENUMERATED;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:85:31: error: redefinition of typedef 'ASN1_BIT_STRING' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_BIT_STRING;
                              ^
third_party/boringssl/include/openssl/base.h:238:31: note: previous definition is here
typedef struct asn1_string_st ASN1_BIT_STRING;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:86:31: error: redefinition of typedef 'ASN1_OCTET_STRING' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_OCTET_STRING;
                              ^
third_party/boringssl/include/openssl/base.h:245:31: note: previous definition is here
typedef struct asn1_string_st ASN1_OCTET_STRING;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:87:31: error: redefinition of typedef 'ASN1_PRINTABLESTRING' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_PRINTABLESTRING;
                              ^
third_party/boringssl/include/openssl/base.h:246:31: note: previous definition is here
typedef struct asn1_string_st ASN1_PRINTABLESTRING;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:88:31: error: redefinition of typedef 'ASN1_T61STRING' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_T61STRING;
                              ^
third_party/boringssl/include/openssl/base.h:248:31: note: previous definition is here
typedef struct asn1_string_st ASN1_T61STRING;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:89:31: error: redefinition of typedef 'ASN1_IA5STRING' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_IA5STRING;
                              ^
third_party/boringssl/include/openssl/base.h:243:31: note: previous definition is here
typedef struct asn1_string_st ASN1_IA5STRING;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:90:31: error: redefinition of typedef 'ASN1_GENERALSTRING' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_GENERALSTRING;
                              ^
third_party/boringssl/include/openssl/base.h:242:31: note: previous definition is here
typedef struct asn1_string_st ASN1_GENERALSTRING;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:91:31: error: redefinition of typedef 'ASN1_UNIVERSALSTRING' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_UNIVERSALSTRING;
                              ^
third_party/boringssl/include/openssl/base.h:250:31: note: previous definition is here
typedef struct asn1_string_st ASN1_UNIVERSALSTRING;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:92:31: error: redefinition of typedef 'ASN1_BMPSTRING' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_BMPSTRING;
                              ^
third_party/boringssl/include/openssl/base.h:239:31: note: previous definition is here
typedef struct asn1_string_st ASN1_BMPSTRING;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:93:31: error: redefinition of typedef 'ASN1_UTCTIME' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_UTCTIME;
                              ^
third_party/boringssl/include/openssl/base.h:251:31: note: previous definition is here
typedef struct asn1_string_st ASN1_UTCTIME;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:94:31: error: redefinition of typedef 'ASN1_TIME' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_TIME;
                              ^
third_party/boringssl/include/openssl/base.h:249:31: note: previous definition is here
typedef struct asn1_string_st ASN1_TIME;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:95:31: error: redefinition of typedef 'ASN1_GENERALIZEDTIME' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_GENERALIZEDTIME;
                              ^
third_party/boringssl/include/openssl/base.h:241:31: note: previous definition is here
typedef struct asn1_string_st ASN1_GENERALIZEDTIME;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:96:31: error: redefinition of typedef 'ASN1_VISIBLESTRING' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_VISIBLESTRING;
                              ^
third_party/boringssl/include/openssl/base.h:253:31: note: previous definition is here
typedef struct asn1_string_st ASN1_VISIBLESTRING;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:97:31: error: redefinition of typedef 'ASN1_UTF8STRING' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_UTF8STRING;
                              ^
third_party/boringssl/include/openssl/base.h:252:31: note: previous definition is here
typedef struct asn1_string_st ASN1_UTF8STRING;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:98:31: error: redefinition of typedef 'ASN1_STRING' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef struct asn1_string_st ASN1_STRING;
                              ^
third_party/boringssl/include/openssl/base.h:247:31: note: previous definition is here
typedef struct asn1_string_st ASN1_STRING;
                              ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:99:13: error: redefinition of typedef 'ASN1_BOOLEAN' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef int ASN1_BOOLEAN;
            ^
third_party/boringssl/include/openssl/base.h:233:13: note: previous definition is here
typedef int ASN1_BOOLEAN;
            ^
In file included from src/boringssl/err_data.c:18:
In file included from /opt/local/include/openssl/err.h:122:
/opt/local/include/openssl/ossl_typ.h:100:13: error: redefinition of typedef 'ASN1_NULL' is a C11 feature [-Werror,-Wtypedef-redefinition]
typedef int ASN1_NULL;
            ^
third_party/boringssl/include/openssl/base.h:234:13: note: previous definition is here
typedef int ASN1_NULL;
            ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.
make: *** [../pip-install-so7ktzhu/grpcio/objs/opt/src/boringssl/err_data.o] Error 1
"

What version of gRPC and what language are you using?

the last commit on the master branch

What operating system (Linux, Windows, …) and version?

macOS, 17.7.0 Darwin Kernel

What runtime / compiler are you using (e.g. python version or version of gcc)

Apple LLVM version 9.1.0 (clang-902.0.39.2)

What did you do?

python3 setup.py build or pypy3 setup.py build

Standalone boringssl from the master branch can be compiled as expected with no errors:

mkdir build
cd build
cmake ..
make