Fix OpenSSL::Engine build on Debian

[tomstuart]

On Debian 9 (“stretch”) the OPENSSL_NO_STATIC_ENGINE macro is not defined, which causes all the #if HAVE_ENGINE_LOAD_… directives to fail with error: 'HAVE_ENGINE_LOAD_…' is not defined, evaluates to 0 [-Werror,-Wundef] while building TruffleRuby:

ossl_engine.c:111:5: error: 'HAVE_ENGINE_LOAD_4758CCA' is not defined, evaluates to 0 [-Werror,-Wundef]
#if HAVE_ENGINE_LOAD_4758CCA
^
ossl_engine.c:114:5: error: 'HAVE_ENGINE_LOAD_AEP' is not defined, evaluates to 0 [-Werror,-Wundef]
#if HAVE_ENGINE_LOAD_AEP
^
ossl_engine.c:117:5: error: 'HAVE_ENGINE_LOAD_ATALLA' is not defined, evaluates to 0 [-Werror,-Wundef]
#if HAVE_ENGINE_LOAD_ATALLA
^
ossl_engine.c:120:5: error: 'HAVE_ENGINE_LOAD_CHIL' is not defined, evaluates to 0 [-Werror,-Wundef]
#if HAVE_ENGINE_LOAD_CHIL
^
ossl_engine.c:123:5: error: 'HAVE_ENGINE_LOAD_CSWIFT' is not defined, evaluates to 0 [-Werror,-Wundef]
#if HAVE_ENGINE_LOAD_CSWIFT
^
ossl_engine.c:126:5: error: 'HAVE_ENGINE_LOAD_NURON' is not defined, evaluates to 0 [-Werror,-Wundef]
#if HAVE_ENGINE_LOAD_NURON
^
ossl_engine.c:129:5: error: 'HAVE_ENGINE_LOAD_SUREWARE' is not defined, evaluates to 0 [-Werror,-Wundef]
#if HAVE_ENGINE_LOAD_SUREWARE
^
ossl_engine.c:132:5: error: 'HAVE_ENGINE_LOAD_UBSEC' is not defined, evaluates to 0 [-Werror,-Wundef]
#if HAVE_ENGINE_LOAD_UBSEC
^
ossl_engine.c:141:5: error: 'HAVE_ENGINE_LOAD_GMP' is not defined, evaluates to 0 [-Werror,-Wundef]
#if HAVE_ENGINE_LOAD_GMP
^
ossl_engine.c:144:5: error: 'HAVE_ENGINE_LOAD_GOST' is not defined, evaluates to 0 [-Werror,-Wundef]
#if HAVE_ENGINE_LOAD_GOST
^
ossl_engine.c:150:5: error: 'HAVE_ENGINE_LOAD_AESNI' is not defined, evaluates to 0 [-Werror,-Wundef]
#if HAVE_ENGINE_LOAD_AESNI
^
compiling ossl_pkcs12.c
11 errors generated.
Makefile:514: recipe for target 'ossl_engine.o' failed

This appears to be happening because the OPENSSL_NO_STATIC_ENGINE macro is undefined on Debian 9.

We can accomplish the same thing with #ifdef, which (of course) works fine when the HAVE_ENGINE_LOAD… macros are also undefined.

Upstreamed from truffleruby/truffleruby#2255, which fixed truffleruby/truffleruby#2254.

[rhenium]

Thanks.

-Wundef would also generate a warning on the use of HAVE_RB_EXT_RACTOR_SAFE macro, which didn't exist before Ruby 3.0. Should they be updated to using #ifdef, too?

[eregon]

Yes, I think it should be #ifdef HAVE_RB_EXT_RACTOR_SAFE and not #if HAVE_RB_EXT_RACTOR_SAFE. Currently openssl master seems to have a mix of both.

I think adding -Wundef to openssl's extconf.rb might be useful to detect such issues early on.

TruffleRuby enables -Wundef for all core C extensions since it can be very confusing that #if DOES_NOT_EXIST silently behaves as not running the code, and also not warn about the missing macro (without -Wundef).

[tomstuart]

OK, I’ve updated all occurrences of HAVE_RB_EXT_RACTOR_SAFE to use #ifdef too.

[rhenium]

Thank you, merged now.

I think adding -Wundef to openssl's extconf.rb might be useful to detect such issues early on.

These occurrences of #if were clearly unintended and I agree it's useful, but I think it's something that should be set by ruby's configure, not openssl's extconf.rb.

[eregon]

Agreed, I'll open a ticket on bugs.ruby-lang.org to suggest using -Wundef.

[eregon]

Filed as https://bugs.ruby-lang.org/issues/17752