Fix compilation of num on 4.x bytecode-only architectures

[dra27]

Comment in the code explains the underlying slightly weird issue. 5.x behaves more logically with these variables - I happened to stumble across this oddity with some relocatable stuff.

As it happens, fixes #39 - but it would be better if --disable-native-compiler were instead being specified here.

[xavierleroy]

LGTM. I fixed a typo directly. Thanks for having looked into this.

[barracuda156]

@dra27 Besides, does bytecode-only automatically imply NATDYNLINK = false?

[dra27]

@dra27 Besides, does bytecode-only automatically imply NATDYNLINK = false?

I’m not sure what you mean by “automatically”. In the 4.x configure script, a bytecode-only architecture wasn’t expected, and you don’t get the correct configuration unless --disable-native-compiler is given explicitly. If you do that, then both NATIVE_COMPILER and NATDYNLINK are set correctly to false, but otherwise they’ll both be true.

[dra27]

I fixed a typo directly.

Ouch - I’d like to blame autocorrect, but Vim insists it doesn’t do that 🫣

[barracuda156]

@dra27 I just did not know that NATDYNLINK implied NATIVE_COMPILER. I assumed it stood for something like “dynamic linking is natively supported on a platform”.

[xavierleroy]

No problem. NATDYNLINK specifically refers to the dynamic loading of native code produced by ocamlopt from OCaml sources. So you need both ocamlopt and dynamic loading facilities a la dlopen.