Commit 54f2898fe7e4ca1f239e96284af3cc5b34d2ae02 (bpo-40645) introduced the functions HMAC_CTX_new, HMAC_CTX_free, and HMAC_CTX_get_md.

These functions share the same names as HMAC functions provided by OpenSSL/LibreSSL. If you attempt to statically link the _hashlib extension as a builtin extension module that is also statically linked against a libcrytpo that provides these functions, the linker may complain about duplicate symbols:

cpython-3.9> /tools/host/bin/ld: /tools/deps/lib/libcrypto.a(libcrypto_la-hmac.o): in function `HMAC_CTX_free':
cpython-3.9> hmac.c:(.text+0x7d0): multiple definition of `HMAC_CTX_free';
cpython-3.9> Modules/_hashopenssl.o:/build/Python-3.9.0/./Modules/_hashopenssl.c:54: first defined here
cpython-3.9> /tools/host/bin/ld: /tools/deps/lib/libcrypto.a(libcrypto_la-hmac.o): in function `HMAC_CTX_get_md':
cpython-3.9> hmac.c:(.text+0xa20): multiple definition of `HMAC_CTX_get_md'; Modules/_hashopenssl.o:/build/Python-3.9.0/./Modules/_hashopenssl.c:                 63: first defined here
cpython-3.9> /tools/host/bin/ld: /tools/deps/lib/libcrypto.a(libcrypto_la-hmac.o): in function `HMAC_CTX_new':
cpython-3.9> hmac.c:(.text+0x780): multiple definition of `HMAC_CTX_new'; Modules/_hashopenssl.o:/build/Python-3.9.0/./Modules/_hashopenssl.c:42:                  first defined here
cpython-3.9> clang-10: error: linker command failed with exit code 1 (use -v to see invocation)
cpython-3.9> ln: failed to access 'libpython3.9.so.1.0': No such file or directory
cpython-3.9> make: *** [libpython3.9.so] Error 1
cpython-3.9> Makefile:656: recipe for target 'libpython3.9.so' failed

This log from a build attempting to statically link against LibreSSL 3.1.4. The issue does not reproduce against OpenSSL 1.1.1h for some reason.

While statically linking _hashlib as a built-in extension module and statically linking libcrypto isn't in the default configuration, I believe this use case should be supported.

Perhaps these 3 functions should be renamed to not conflict with symbols provided by libcrypto?