Okay if the libgccjit feature is not available we raise an error, but
how the user is supposed to test for this feature without compiling?
'comp-libgccjit-version' starts working only if gcc_jit_version_major is
available otherwise return nil, and I added gcc_jit_version_major into
GCC10 :/
We need to offer a way to the user to check for that before going for
compilation. The only idea I've at the moment is that we expose a
function to set these instead of using 'comp-native-driver-options'.
Ah! That's a good point about users being unable to tell if their options will work until they try to compile.
I would like to keep the driver-option setting interface as a variable holding a list, as that still allows users to edit them with the emacs-provided functions to do so. With a function accessor, we'd have to add functions to add/remove/map over/etc the options, which emacs already provides with `add-to-list' and friends.
I think we could expose a predicate `comp-native-driver-options-available-p' that'll return t if the necessary facility exists.
For some extra credit, maybe we could even have that predicate test whether a given set of driver options has a chance of succeeding (I guess that this would have to attempt a no-op compile to exercise the compiler->linker chain). A predicate to test for compatibility would be the nicest and would fit the bill well, though.